vhost: convert vhost device driver to a plugin

convert vhost device driver to a plugin as described in
https://jira.fd.io/browse/VPP-2065

Type: improvement

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: Ibfe2f351bcaed36a04b136d082ae414145dd37b5

12 files changed, 6999 insertions, 0 deletions

diff --git a/src/plugins/vhost/CMakeLists.txt b/src/plugins/vhost/CMakeLists.txt
new file mode 100644
index 00000000000..f72d9f20346
--- /dev/null
+++ b/src/plugins/vhost/CMakeLists.txt
@@ -0,0 +1,32 @@
+# Copyright (c) 2020 Cisco and/or its affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+add_vpp_plugin(vhost
+  SOURCES
+  plugin.c
+  vhost_user.c
+  vhost_user_api.c
+  vhost_user_input.c
+  vhost_user_output.c
+  vhost_std.h
+  vhost_user.h
+  vhost_user_inline.h
+  virtio_std.h
+
+  MULTIARCH_SOURCES
+  vhost_user_input.c
+  vhost_user_output.c
+
+  API_FILES
+  vhost_user.api
+)
diff --git a/src/plugins/vhost/FEATURE.yaml b/src/plugins/vhost/FEATURE.yaml
new file mode 100644
index 00000000000..7104dda1dc5
--- /dev/null
+++ b/src/plugins/vhost/FEATURE.yaml
@@ -0,0 +1,13 @@
+---
+name: Vhost-user Device Driver
+maintainer: sluong@cisco.com
+features:
+  - Device mode to emulate vhost-user interface presented to VPP from the
+    guest VM.
+  - Support virtio 1.0 in virtio
+  - Support virtio 1.1 packed ring in virtio [experimental]
+  - Support multi-queue, GSO, checksum offload, indirect descriptor,
+    jumbo frame, and packed ring.
+description: "Vhost-user implementation"
+state: production
+properties: [API, CLI, STATS, MULTITHREAD]
diff --git a/src/plugins/vhost/plugin.c b/src/plugins/vhost/plugin.c
new file mode 100644
index 00000000000..dc5de1c9ed8
--- /dev/null
+++ b/src/plugins/vhost/plugin.c
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2022 Cisco Systems, Inc.
+ * License: Cisco Proprietary Closed Source License - Cisco Internal.
+ * The software, documentation and any fonts accompanying this License whether
+ * on disk, in read only memory, on any other media or in any other form (col-
+ * lectively the “Software”) are licensed, not sold, to you by Cisco, Inc.
+ * (“Cisco”) for use only under the terms of this License, and Cisco reserves
+ * all rights not expressly granted to you. The rights granted herein are
+ * limited to Cisco’s intel- lectual property rights in the Cisco Software and
+ * do not include any other patents or intellectual property rights. You own
+ * the media on which the Cisco Software is recorded but Cisco and/or Cisco’s
+ * licensor(s) retain ownership of the Software itself.
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/plugin/plugin.h>
+#include <vpp/app/version.h>
+
+VLIB_PLUGIN_REGISTER () = {
+  .version = VPP_BUILD_VER,
+  .description = "Vhost-User",
+};
diff --git a/src/plugins/vhost/vhost_std.h b/src/plugins/vhost/vhost_std.h
new file mode 100644
index 00000000000..7799093bac3
--- /dev/null
+++ b/src/plugins/vhost/vhost_std.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __VHOST_STD_H__
+#define __VHOST_STD_H__
+
+typedef struct
+{
+  u64 guest_phys_addr;
+  u64 memory_size;
+  u64 userspace_addr;
+  u64 mmap_offset;
+} vhost_memory_region_t;
+
+typedef struct
+{
+  u32 nregions;
+  u32 padding;
+  vhost_memory_region_t regions[0];
+} vhost_memory_t;
+
+typedef struct
+{
+  u32 index;
+  u32 num;
+} vhost_vring_state_t;
+
+typedef struct
+{
+  u32 index;
+  int fd;
+} vhost_vring_file_t;
+
+typedef struct
+{
+  u32 index;
+  u32 flags;
+  u64 desc_user_addr;
+  u64 used_user_addr;
+  u64 avail_user_addr;
+  u64 log_guest_addr;
+} vhost_vring_addr_t;
+
+typedef struct
+{
+  u64 size;
+  u64 offset;
+} vhost_user_log_t;
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user.api b/src/plugins/vhost/vhost_user.api
new file mode 100644
index 00000000000..b026ba768a9
--- /dev/null
+++ b/src/plugins/vhost/vhost_user.api
@@ -0,0 +1,201 @@
+/*
+ * Copyright (c) 2015-2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+option version = "4.1.1";
+
+import "vnet/interface_types.api";
+import "vnet/ethernet/ethernet_types.api";
+import "vnet/devices/virtio/virtio_types.api";
+
+/** \brief vhost-user interface create request
+    @param client_index - opaque cookie to identify the sender
+    @param is_server - our side is socket server
+    @param sock_filename - unix socket filename, used to speak with frontend
+    @param use_custom_mac - enable or disable the use of the provided hardware address
+    @param disable_mrg_rxbuf - disable the use of merge receive buffers
+    @param disable_indirect_desc - disable the use of indirect descriptors which driver can use
+    @param enable_gso - enable gso support (default 0)
+    @param enable_packed - enable packed ring support (default 0)
+    @param mac_address - hardware address to use if 'use_custom_mac' is set
+*/
+define create_vhost_user_if
+{
+  option deprecated;
+  u32 client_index;
+  u32 context;
+  bool is_server;
+  string sock_filename[256];
+  bool renumber;
+  bool disable_mrg_rxbuf;
+  bool disable_indirect_desc;
+  bool enable_gso;
+  bool enable_packed;
+  u32 custom_dev_instance;
+  bool use_custom_mac;
+  vl_api_mac_address_t mac_address;
+  string tag[64];
+};
+
+/** \brief vhost-user interface create response
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+    @param sw_if_index - interface the operation is applied to
+*/
+define create_vhost_user_if_reply
+{
+  option deprecated;
+  u32 context;
+  i32 retval;
+  vl_api_interface_index_t sw_if_index;
+};
+
+/** \brief vhost-user interface modify request
+    @param client_index - opaque cookie to identify the sender
+    @param is_server - our side is socket server
+    @param sock_filename - unix socket filename, used to speak with frontend
+    @param enable_gso - enable gso support (default 0)
+    @param enable_packed - enable packed ring support (default 0)
+*/
+autoreply define modify_vhost_user_if
+{
+  option deprecated;
+  u32 client_index;
+  u32 context;
+  vl_api_interface_index_t sw_if_index;
+  bool is_server;
+  string sock_filename[256];
+  bool renumber;
+  bool enable_gso;
+  bool enable_packed;
+  u32 custom_dev_instance;
+};
+
+/** \brief vhost-user interface create request
+    @param client_index - opaque cookie to identify the sender
+    @param is_server - our side is socket server
+    @param sock_filename - unix socket filename, used to speak with frontend
+    @param use_custom_mac - enable or disable the use of the provided hardware address
+    @param disable_mrg_rxbuf - disable the use of merge receive buffers
+    @param disable_indirect_desc - disable the use of indirect descriptors which driver can use
+    @param enable_gso - enable gso support (default 0)
+    @param enable_packed - enable packed ring support (default 0)
+    @param enable_event_idx - enable event_idx support (default 0)
+    @param mac_address - hardware address to use if 'use_custom_mac' is set
+    @param renumber - if true, use custom_dev_instance is valid
+    @param custom_dev_instance - custom device instance number
+*/
+define create_vhost_user_if_v2
+{
+  u32 client_index;
+  u32 context;
+  bool is_server;
+  string sock_filename[256];
+  bool renumber;
+  bool disable_mrg_rxbuf;
+  bool disable_indirect_desc;
+  bool enable_gso;
+  bool enable_packed;
+  bool enable_event_idx;
+  u32 custom_dev_instance;
+  bool use_custom_mac;
+  vl_api_mac_address_t mac_address;
+  string tag[64];
+};
+
+/** \brief vhost-user interface create response
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+    @param sw_if_index - interface the operation is applied to
+*/
+define create_vhost_user_if_v2_reply
+{
+  u32 context;
+  i32 retval;
+  vl_api_interface_index_t sw_if_index;
+};
+
+/** \brief vhost-user interface modify request
+    @param client_index - opaque cookie to identify the sender
+    @param is_server - our side is socket server
+    @param sock_filename - unix socket filename, used to speak with frontend
+    @param enable_gso - enable gso support (default 0)
+    @param enable_packed - enable packed ring support (default 0)
+    @param enable_event_idx - enable event idx support (default 0)
+    @param renumber - if true, use custom_dev_instance is valid
+    @param custom_dev_instance - custom device instance number
+*/
+autoreply define modify_vhost_user_if_v2
+{
+  u32 client_index;
+  u32 context;
+  vl_api_interface_index_t sw_if_index;
+  bool is_server;
+  string sock_filename[256];
+  bool renumber;
+  bool enable_gso;
+  bool enable_packed;
+  bool enable_event_idx;
+  u32 custom_dev_instance;
+};
+
+/** \brief vhost-user interface delete request
+    @param client_index - opaque cookie to identify the sender
+*/
+autoreply define delete_vhost_user_if
+{
+  u32 client_index;
+  u32 context;
+  vl_api_interface_index_t sw_if_index;
+};
+
+/** \brief Vhost-user interface details structure (fix this)
+    @param sw_if_index - index of the interface
+    @param interface_name - name of interface
+    @param virtio_net_hdr_sz - net header size
+    @param features_first_32 - interface features, first 32 bits
+    @param features_last_32 - interface features, last 32 bits
+    @param is_server - vhost-user server socket
+    @param sock_filename - socket filename
+    @param num_regions - number of used memory regions
+    @param sock_errno - socket errno
+*/
+define sw_interface_vhost_user_details
+{
+  u32 context;
+  vl_api_interface_index_t sw_if_index;
+  string interface_name[64];
+  u32 virtio_net_hdr_sz;
+  vl_api_virtio_net_features_first_32_t features_first_32;
+  vl_api_virtio_net_features_last_32_t features_last_32;
+  bool is_server;
+  string sock_filename[256];
+  u32 num_regions;
+  i32 sock_errno;
+};
+
+/** \brief Vhost-user interface dump request
+    @param sw_if_index - filter by sw_if_index
+*/
+define sw_interface_vhost_user_dump
+{
+  u32 client_index;
+  u32 context;
+  vl_api_interface_index_t sw_if_index [default=0xffffffff];
+};
+/*
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user.c b/src/plugins/vhost/vhost_user.c
new file mode 100644
index 00000000000..fac20800848
--- /dev/null
+++ b/src/plugins/vhost/vhost_user.c
@@ -0,0 +1,2613 @@
+/*
+ *------------------------------------------------------------------
+ * vhost.c - vhost-user
+ *
+ * Copyright (c) 2014-2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#include <fcntl.h>		/* for open */
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/uio.h>		/* for iovec */
+#include <netinet/in.h>
+#include <sys/vfs.h>
+
+#include <linux/if_arp.h>
+#include <linux/if_tun.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/devices.h>
+#include <vnet/feature/feature.h>
+#include <vnet/interface/rx_queue_funcs.h>
+#include <vnet/interface/tx_queue_funcs.h>
+
+#include <vhost/vhost_user.h>
+#include <vhost/vhost_user_inline.h>
+
+/**
+ * @file
+ * @brief vHost User Device Driver.
+ *
+ * This file contains the source code for vHost User interface.
+ */
+
+
+vlib_node_registration_t vhost_user_send_interrupt_node;
+
+/* *INDENT-OFF* */
+vhost_user_main_t vhost_user_main = {
+  .mtu_bytes = 1518,
+};
+
+VNET_HW_INTERFACE_CLASS (vhost_interface_class, static) = {
+  .name = "vhost-user",
+};
+/* *INDENT-ON* */
+
+static long
+get_huge_page_size (int fd)
+{
+  struct statfs s;
+  fstatfs (fd, &s);
+  return s.f_bsize;
+}
+
+static void
+unmap_all_mem_regions (vhost_user_intf_t * vui)
+{
+  int i, r, q;
+  vhost_user_vring_t *vq;
+
+  for (i = 0; i < vui->nregions; i++)
+    {
+      if (vui->region_mmap_addr[i] != MAP_FAILED)
+	{
+
+	  long page_sz = get_huge_page_size (vui->region_mmap_fd[i]);
+
+	  ssize_t map_sz = (vui->regions[i].memory_size +
+			    vui->regions[i].mmap_offset +
+			    page_sz - 1) & ~(page_sz - 1);
+
+	  r =
+	    munmap (vui->region_mmap_addr[i] - vui->regions[i].mmap_offset,
+		    map_sz);
+
+	  vu_log_debug (vui, "unmap memory region %d addr 0x%lx len 0x%lx "
+			"page_sz 0x%x", i, vui->region_mmap_addr[i], map_sz,
+			page_sz);
+
+	  vui->region_mmap_addr[i] = MAP_FAILED;
+
+	  if (r == -1)
+	    {
+	      vu_log_err (vui, "failed to unmap memory region (errno %d)",
+			  errno);
+	    }
+	  close (vui->region_mmap_fd[i]);
+	}
+    }
+  vui->nregions = 0;
+
+  FOR_ALL_VHOST_RX_TXQ (q, vui)
+  {
+    vq = &vui->vrings[q];
+    vq->avail = 0;
+    vq->used = 0;
+    vq->desc = 0;
+  }
+}
+
+static_always_inline void
+vhost_user_tx_thread_placement (vhost_user_intf_t *vui, u32 qid)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  vhost_user_vring_t *rxvq = &vui->vrings[qid];
+  u32 q = qid >> 1, rxvq_count;
+
+  ASSERT ((qid & 1) == 0);
+  if (!rxvq->started || !rxvq->enabled)
+    return;
+
+  rxvq_count = (qid >> 1) + 1;
+  if (rxvq->queue_index == ~0)
+    {
+      rxvq->queue_index =
+	vnet_hw_if_register_tx_queue (vnm, vui->hw_if_index, q);
+      rxvq->qid = q;
+    }
+
+  FOR_ALL_VHOST_RXQ (q, vui)
+  {
+    vhost_user_vring_t *rxvq = &vui->vrings[q];
+    u32 qi = rxvq->queue_index;
+
+    if (rxvq->queue_index == ~0)
+      break;
+    for (u32 i = 0; i < vlib_get_n_threads (); i++)
+      vnet_hw_if_tx_queue_unassign_thread (vnm, qi, i);
+  }
+
+  for (u32 i = 0; i < vlib_get_n_threads (); i++)
+    {
+      vhost_user_vring_t *rxvq =
+	&vui->vrings[VHOST_VRING_IDX_RX (i % rxvq_count)];
+      u32 qi = rxvq->queue_index;
+
+      vnet_hw_if_tx_queue_assign_thread (vnm, qi, i);
+    }
+
+  vnet_hw_if_update_runtime_data (vnm, vui->hw_if_index);
+}
+
+/**
+ * @brief Unassign existing interface/queue to thread mappings and re-assign
+ * new interface/queue to thread mappings
+ */
+static_always_inline void
+vhost_user_rx_thread_placement (vhost_user_intf_t * vui, u32 qid)
+{
+  vhost_user_vring_t *txvq = &vui->vrings[qid];
+  vnet_main_t *vnm = vnet_get_main ();
+  int rv;
+  u32 q = qid >> 1;
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  ASSERT ((qid & 1) == 1);	// should be odd
+  // Assign new queue mappings for the interface
+  if (txvq->queue_index != ~0)
+    return;
+  vnet_hw_if_set_input_node (vnm, vui->hw_if_index,
+			     vhost_user_input_node.index);
+  txvq->queue_index = vnet_hw_if_register_rx_queue (vnm, vui->hw_if_index, q,
+						    VNET_HW_IF_RXQ_THREAD_ANY);
+  txvq->thread_index =
+    vnet_hw_if_get_rx_queue_thread_index (vnm, txvq->queue_index);
+
+  if (txvq->mode == VNET_HW_IF_RX_MODE_UNKNOWN)
+    /* Set polling as the default */
+    txvq->mode = VNET_HW_IF_RX_MODE_POLLING;
+  if (txvq->mode == VNET_HW_IF_RX_MODE_POLLING)
+    {
+      vhost_cpu_t *cpu = vec_elt_at_index (vum->cpus, txvq->thread_index);
+      /* Keep a polling queue count for each thread */
+      cpu->polling_q_count++;
+    }
+  txvq->qid = q;
+  rv = vnet_hw_if_set_rx_queue_mode (vnm, txvq->queue_index, txvq->mode);
+  if (rv)
+    vu_log_warn (vui, "unable to set rx mode for interface %d, "
+		 "queue %d: rc=%d", vui->hw_if_index, q, rv);
+  vnet_hw_if_update_runtime_data (vnm, vui->hw_if_index);
+}
+
+/** @brief Returns whether at least one TX and one RX vring are enabled */
+static_always_inline int
+vhost_user_intf_ready (vhost_user_intf_t * vui)
+{
+  int i, found[2] = { };	//RX + TX
+
+  for (i = 0; i < vui->num_qid; i++)
+    if (vui->vrings[i].started && vui->vrings[i].enabled)
+      found[i & 1] = 1;
+
+  return found[0] && found[1];
+}
+
+static_always_inline void
+vhost_user_update_iface_state (vhost_user_intf_t * vui)
+{
+  /* if we have pointers to descriptor table, go up */
+  int is_ready = vhost_user_intf_ready (vui);
+  if (is_ready != vui->is_ready)
+    {
+      vu_log_debug (vui, "interface %d %s", vui->sw_if_index,
+		    is_ready ? "ready" : "down");
+      if (vui->admin_up)
+	vnet_hw_interface_set_flags (vnet_get_main (), vui->hw_if_index,
+				     is_ready ? VNET_HW_INTERFACE_FLAG_LINK_UP
+				     : 0);
+      vui->is_ready = is_ready;
+    }
+}
+
+static clib_error_t *
+vhost_user_callfd_read_ready (clib_file_t * uf)
+{
+  __attribute__ ((unused)) int n;
+  u8 buff[8];
+
+  n = read (uf->file_descriptor, ((char *) &buff), 8);
+
+  return 0;
+}
+
+static_always_inline void
+vhost_user_thread_placement (vhost_user_intf_t * vui, u32 qid)
+{
+  if (qid & 1)			// RX is odd, TX is even
+    {
+      if (vui->vrings[qid].queue_index == ~0)
+	vhost_user_rx_thread_placement (vui, qid);
+    }
+  else
+    vhost_user_tx_thread_placement (vui, qid);
+}
+
+static clib_error_t *
+vhost_user_kickfd_read_ready (clib_file_t * uf)
+{
+  __attribute__ ((unused)) ssize_t n;
+  u8 buff[8];
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data >> 8);
+  u32 qid = uf->private_data & 0xff;
+  u32 is_txq = qid & 1;
+  vhost_user_vring_t *vq = &vui->vrings[qid];
+  vnet_main_t *vnm = vnet_get_main ();
+
+  n = read (uf->file_descriptor, buff, 8);
+  if (vq->started == 0)
+    {
+      vq->started = 1;
+      vhost_user_thread_placement (vui, qid);
+      vhost_user_update_iface_state (vui);
+      if (is_txq)
+	vnet_hw_if_set_rx_queue_file_index (vnm, vq->queue_index,
+					    vq->kickfd_idx);
+    }
+
+  if (is_txq && (vq->mode != VNET_HW_IF_RX_MODE_POLLING) &&
+      vhost_user_intf_ready (vui))
+    {
+      vhost_cpu_t *cpu = vec_elt_at_index (vum->cpus, vq->thread_index);
+      /*
+       * If the thread has more than 1 queue and the other queue is in polling
+       * mode, there is no need to trigger an interrupt
+       */
+      if (cpu->polling_q_count == 0)
+	vnet_hw_if_rx_queue_set_int_pending (vnm, vq->queue_index);
+    }
+
+  return 0;
+}
+
+static_always_inline void
+vhost_user_vring_init (vhost_user_intf_t * vui, u32 qid)
+{
+  vhost_user_vring_t *vring = &vui->vrings[qid];
+
+  clib_memset (vring, 0, sizeof (*vring));
+  vring->kickfd_idx = ~0;
+  vring->callfd_idx = ~0;
+  vring->errfd = -1;
+  vring->qid = -1;
+  vring->queue_index = ~0;
+  vring->thread_index = ~0;
+  vring->mode = VNET_HW_IF_RX_MODE_POLLING;
+
+  clib_spinlock_init (&vring->vring_lock);
+
+  /*
+   * We have a bug with some qemu 2.5, and this may be a fix.
+   * Feel like interpretation holy text, but this is from vhost-user.txt.
+   * "
+   * One queue pair is enabled initially. More queues are enabled
+   * dynamically, by sending message VHOST_USER_SET_VRING_ENABLE.
+   * "
+   * Don't know who's right, but this is what DPDK does.
+   */
+  if (qid == 0 || qid == 1)
+    vring->enabled = 1;
+}
+
+static_always_inline void
+vhost_user_vring_close (vhost_user_intf_t * vui, u32 qid)
+{
+  vhost_user_vring_t *vring = &vui->vrings[qid];
+
+  if (vring->kickfd_idx != ~0)
+    {
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
+					   vring->kickfd_idx);
+      clib_file_del (&file_main, uf);
+      vring->kickfd_idx = ~0;
+    }
+  if (vring->callfd_idx != ~0)
+    {
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
+					   vring->callfd_idx);
+      clib_file_del (&file_main, uf);
+      vring->callfd_idx = ~0;
+    }
+  if (vring->errfd != -1)
+    {
+      close (vring->errfd);
+      vring->errfd = -1;
+    }
+
+  clib_spinlock_free (&vring->vring_lock);
+
+  // save the needed information in vrings prior to being wiped out
+  u16 q = vui->vrings[qid].qid;
+  u32 queue_index = vui->vrings[qid].queue_index;
+  u32 mode = vui->vrings[qid].mode;
+  u32 thread_index = vui->vrings[qid].thread_index;
+  vhost_user_vring_init (vui, qid);
+  vui->vrings[qid].qid = q;
+  vui->vrings[qid].queue_index = queue_index;
+  vui->vrings[qid].mode = mode;
+  vui->vrings[qid].thread_index = thread_index;
+}
+
+static_always_inline void
+vhost_user_if_disconnect (vhost_user_intf_t * vui)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  int q;
+
+  vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
+
+  if (vui->clib_file_index != ~0)
+    {
+      clib_file_del (&file_main, file_main.file_pool + vui->clib_file_index);
+      vui->clib_file_index = ~0;
+    }
+
+  vui->is_ready = 0;
+
+  FOR_ALL_VHOST_RX_TXQ (q, vui) { vhost_user_vring_close (vui, q); }
+
+  unmap_all_mem_regions (vui);
+  vu_log_debug (vui, "interface ifindex %d disconnected", vui->sw_if_index);
+}
+
+void
+vhost_user_set_operation_mode (vhost_user_intf_t *vui,
+			       vhost_user_vring_t *txvq)
+{
+  if (vhost_user_is_packed_ring_supported (vui))
+    {
+      if (txvq->used_event)
+	{
+	  if (txvq->mode == VNET_HW_IF_RX_MODE_POLLING)
+	    txvq->used_event->flags = VRING_EVENT_F_DISABLE;
+	  else
+	    txvq->used_event->flags = 0;
+	}
+    }
+  else
+    {
+      if (txvq->used)
+	{
+	  if (txvq->mode == VNET_HW_IF_RX_MODE_POLLING)
+	    txvq->used->flags = VRING_USED_F_NO_NOTIFY;
+	  else
+	    txvq->used->flags = 0;
+	}
+    }
+}
+
+static clib_error_t *
+vhost_user_socket_read (clib_file_t * uf)
+{
+  int n, i, j;
+  int fd, number_of_fds = 0;
+  int fds[VHOST_MEMORY_MAX_NREGIONS];
+  vhost_user_msg_t msg;
+  struct msghdr mh;
+  struct iovec iov[1];
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  struct cmsghdr *cmsg;
+  u8 q;
+  clib_file_t template = { 0 };
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data);
+
+  char control[CMSG_SPACE (VHOST_MEMORY_MAX_NREGIONS * sizeof (int))];
+
+  clib_memset (&mh, 0, sizeof (mh));
+  clib_memset (control, 0, sizeof (control));
+
+  for (i = 0; i < VHOST_MEMORY_MAX_NREGIONS; i++)
+    fds[i] = -1;
+
+  /* set the payload */
+  iov[0].iov_base = (void *) &msg;
+  iov[0].iov_len = VHOST_USER_MSG_HDR_SZ;
+
+  mh.msg_iov = iov;
+  mh.msg_iovlen = 1;
+  mh.msg_control = control;
+  mh.msg_controllen = sizeof (control);
+
+  n = recvmsg (uf->file_descriptor, &mh, 0);
+
+  if (n != VHOST_USER_MSG_HDR_SZ)
+    {
+      if (n == -1)
+	{
+	  vu_log_debug (vui, "recvmsg returned error %d %s", errno,
+			strerror (errno));
+	}
+      else
+	{
+	  vu_log_debug (vui, "n (%d) != VHOST_USER_MSG_HDR_SZ (%d)",
+			n, VHOST_USER_MSG_HDR_SZ);
+	}
+      goto close_socket;
+    }
+
+  if (mh.msg_flags & MSG_CTRUNC)
+    {
+      vu_log_debug (vui, "MSG_CTRUNC is set");
+      goto close_socket;
+    }
+
+  cmsg = CMSG_FIRSTHDR (&mh);
+
+  if (cmsg && (cmsg->cmsg_len > 0) && (cmsg->cmsg_level == SOL_SOCKET) &&
+      (cmsg->cmsg_type == SCM_RIGHTS) &&
+      (cmsg->cmsg_len - CMSG_LEN (0) <=
+       VHOST_MEMORY_MAX_NREGIONS * sizeof (int)))
+    {
+      number_of_fds = (cmsg->cmsg_len - CMSG_LEN (0)) / sizeof (int);
+      clib_memcpy_fast (fds, CMSG_DATA (cmsg), number_of_fds * sizeof (int));
+    }
+
+  /* version 1, no reply bit set */
+  if ((msg.flags & 7) != 1)
+    {
+      vu_log_debug (vui, "malformed message received. closing socket");
+      goto close_socket;
+    }
+
+  {
+    int rv;
+    rv =
+      read (uf->file_descriptor, ((char *) &msg) + VHOST_USER_MSG_HDR_SZ,
+	    msg.size);
+    if (rv < 0)
+      {
+	vu_log_debug (vui, "read failed %s", strerror (errno));
+	goto close_socket;
+      }
+    else if (rv != msg.size)
+      {
+	vu_log_debug (vui, "message too short (read %dB should be %dB)", rv,
+		      msg.size);
+	goto close_socket;
+      }
+  }
+
+  switch (msg.request)
+    {
+    case VHOST_USER_GET_FEATURES:
+      msg.flags |= 4;
+      msg.u64 = VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF) |
+	VIRTIO_FEATURE (VIRTIO_NET_F_CTRL_VQ) |
+	VIRTIO_FEATURE (VIRTIO_F_ANY_LAYOUT) |
+	VIRTIO_FEATURE (VIRTIO_RING_F_INDIRECT_DESC) |
+	VIRTIO_FEATURE (VHOST_F_LOG_ALL) |
+	VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_ANNOUNCE) |
+	VIRTIO_FEATURE (VIRTIO_NET_F_MQ) |
+	VIRTIO_FEATURE (VHOST_USER_F_PROTOCOL_FEATURES) |
+	VIRTIO_FEATURE (VIRTIO_F_VERSION_1);
+      msg.u64 &= vui->feature_mask;
+
+      if (vui->enable_event_idx)
+	msg.u64 |= VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+      if (vui->enable_gso)
+	msg.u64 |= FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS;
+      if (vui->enable_packed)
+	msg.u64 |= VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+
+      msg.size = sizeof (msg.u64);
+      vu_log_debug (vui, "if %d msg VHOST_USER_GET_FEATURES - reply "
+		    "0x%016llx", vui->hw_if_index, msg.u64);
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  vu_log_debug (vui, "could not send message response");
+	  goto close_socket;
+	}
+      break;
+
+    case VHOST_USER_SET_FEATURES:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_FEATURES features "
+		    "0x%016llx", vui->hw_if_index, msg.u64);
+
+      vui->features = msg.u64;
+
+      if (vui->features &
+	  (VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF) |
+	   VIRTIO_FEATURE (VIRTIO_F_VERSION_1)))
+	vui->virtio_net_hdr_sz = 12;
+      else
+	vui->virtio_net_hdr_sz = 10;
+
+      vui->is_any_layout =
+	(vui->features & VIRTIO_FEATURE (VIRTIO_F_ANY_LAYOUT)) ? 1 : 0;
+
+      ASSERT (vui->virtio_net_hdr_sz < VLIB_BUFFER_PRE_DATA_SIZE);
+      if (vui->enable_gso &&
+	  ((vui->features & FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS)
+	   == FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS))
+	{
+	  vnet_hw_if_set_caps (vnm, vui->hw_if_index,
+			       VNET_HW_IF_CAP_TCP_GSO |
+				 VNET_HW_IF_CAP_TX_TCP_CKSUM |
+				 VNET_HW_IF_CAP_TX_UDP_CKSUM);
+	}
+      else
+	{
+	  vnet_hw_if_unset_caps (vnm, vui->hw_if_index,
+				 VNET_HW_IF_CAP_TCP_GSO |
+				   VNET_HW_IF_CAP_L4_TX_CKSUM);
+	}
+      vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
+      vui->is_ready = 0;
+      vhost_user_update_iface_state (vui);
+      break;
+
+    case VHOST_USER_SET_MEM_TABLE:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_MEM_TABLE nregions %d",
+		    vui->hw_if_index, msg.memory.nregions);
+
+      if ((msg.memory.nregions < 1) ||
+	  (msg.memory.nregions > VHOST_MEMORY_MAX_NREGIONS))
+	{
+	  vu_log_debug (vui, "number of mem regions must be between 1 and %i",
+			VHOST_MEMORY_MAX_NREGIONS);
+	  goto close_socket;
+	}
+
+      if (msg.memory.nregions != number_of_fds)
+	{
+	  vu_log_debug (vui, "each memory region must have FD");
+	  goto close_socket;
+	}
+
+      /* Do the mmap without barrier sync */
+      void *region_mmap_addr[VHOST_MEMORY_MAX_NREGIONS];
+      for (i = 0; i < msg.memory.nregions; i++)
+	{
+	  long page_sz = get_huge_page_size (fds[i]);
+
+	  /* align size to page */
+	  ssize_t map_sz = (msg.memory.regions[i].memory_size +
+			    msg.memory.regions[i].mmap_offset +
+			    page_sz - 1) & ~(page_sz - 1);
+
+	  region_mmap_addr[i] = mmap (0, map_sz, PROT_READ | PROT_WRITE,
+				      MAP_SHARED, fds[i], 0);
+	  if (region_mmap_addr[i] == MAP_FAILED)
+	    {
+	      vu_log_err (vui, "failed to map memory. errno is %d", errno);
+	      for (j = 0; j < i; j++)
+		munmap (region_mmap_addr[j], map_sz);
+	      goto close_socket;
+	    }
+	  vu_log_debug (vui, "map memory region %d addr 0 len 0x%lx fd %d "
+			"mapped 0x%lx page_sz 0x%x", i, map_sz, fds[i],
+			region_mmap_addr[i], page_sz);
+	}
+
+      vlib_worker_thread_barrier_sync (vm);
+      unmap_all_mem_regions (vui);
+      for (i = 0; i < msg.memory.nregions; i++)
+	{
+	  clib_memcpy_fast (&(vui->regions[i]), &msg.memory.regions[i],
+			    sizeof (vhost_user_memory_region_t));
+
+	  vui->region_mmap_addr[i] = region_mmap_addr[i];
+	  vui->region_guest_addr_lo[i] = vui->regions[i].guest_phys_addr;
+	  vui->region_guest_addr_hi[i] = vui->regions[i].guest_phys_addr +
+	    vui->regions[i].memory_size;
+
+	  vui->region_mmap_addr[i] += vui->regions[i].mmap_offset;
+	  vui->region_mmap_fd[i] = fds[i];
+
+	  vui->nregions++;
+	}
+
+      /*
+       * Re-compute desc, used, and avail descriptor table if vring address
+       * is set.
+       */
+      FOR_ALL_VHOST_RX_TXQ (q, vui)
+      {
+	if (vui->vrings[q].desc_user_addr && vui->vrings[q].used_user_addr &&
+	    vui->vrings[q].avail_user_addr)
+	  {
+	    vui->vrings[q].desc =
+	      map_user_mem (vui, vui->vrings[q].desc_user_addr);
+	    vui->vrings[q].used =
+	      map_user_mem (vui, vui->vrings[q].used_user_addr);
+	    vui->vrings[q].avail =
+	      map_user_mem (vui, vui->vrings[q].avail_user_addr);
+	  }
+      }
+      vlib_worker_thread_barrier_release (vm);
+      break;
+
+    case VHOST_USER_SET_VRING_NUM:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_VRING_NUM idx %d num %d",
+		    vui->hw_if_index, msg.state.index, msg.state.num);
+
+      if ((msg.state.num > 32768) ||	/* maximum ring size is 32768 */
+	  (msg.state.num == 0) ||	/* it cannot be zero */
+	  ((msg.state.num - 1) & msg.state.num) ||	/* must be power of 2 */
+	  (msg.state.index >= vui->num_qid))
+	{
+	  vu_log_debug (vui, "invalid VHOST_USER_SET_VRING_NUM: msg.state.num"
+			" %d, msg.state.index %d, curruent max q %d",
+			msg.state.num, msg.state.index, vui->num_qid);
+	  goto close_socket;
+	}
+      vui->vrings[msg.state.index].qsz_mask = msg.state.num - 1;
+      break;
+
+    case VHOST_USER_SET_VRING_ADDR:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_VRING_ADDR idx %d",
+		    vui->hw_if_index, msg.state.index);
+
+      if (msg.state.index >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring index VHOST_USER_SET_VRING_ADDR:"
+			" %u >= %u", msg.state.index, vui->num_qid);
+	  goto close_socket;
+	}
+
+      if (msg.size < sizeof (msg.addr))
+	{
+	  vu_log_debug (vui, "vhost message is too short (%d < %d)",
+			msg.size, sizeof (msg.addr));
+	  goto close_socket;
+	}
+
+      vnet_virtio_vring_desc_t *desc =
+	map_user_mem (vui, msg.addr.desc_user_addr);
+      vnet_virtio_vring_used_t *used =
+	map_user_mem (vui, msg.addr.used_user_addr);
+      vnet_virtio_vring_avail_t *avail =
+	map_user_mem (vui, msg.addr.avail_user_addr);
+
+      if ((desc == NULL) || (used == NULL) || (avail == NULL))
+	{
+	  vu_log_debug (vui, "failed to map user memory for hw_if_index %d",
+			vui->hw_if_index);
+	  goto close_socket;
+	}
+
+      vui->vrings[msg.state.index].desc_user_addr = msg.addr.desc_user_addr;
+      vui->vrings[msg.state.index].used_user_addr = msg.addr.used_user_addr;
+      vui->vrings[msg.state.index].avail_user_addr = msg.addr.avail_user_addr;
+
+      vlib_worker_thread_barrier_sync (vm);
+      vui->vrings[msg.state.index].desc = desc;
+      vui->vrings[msg.state.index].used = used;
+      vui->vrings[msg.state.index].avail = avail;
+
+      vui->vrings[msg.state.index].log_guest_addr = msg.addr.log_guest_addr;
+      vui->vrings[msg.state.index].log_used =
+	(msg.addr.flags & (1 << VHOST_VRING_F_LOG)) ? 1 : 0;
+
+      /* Spec says: If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated,
+         the ring is initialized in an enabled state. */
+      if (!(vui->features & VIRTIO_FEATURE (VHOST_USER_F_PROTOCOL_FEATURES)))
+	vui->vrings[msg.state.index].enabled = 1;
+
+      vui->vrings[msg.state.index].last_used_idx =
+	vui->vrings[msg.state.index].last_avail_idx =
+	vui->vrings[msg.state.index].used->idx;
+      vui->vrings[msg.state.index].last_kick =
+	vui->vrings[msg.state.index].last_used_idx;
+
+      /* tell driver that we want interrupts or not */
+      vhost_user_set_operation_mode (vui, &vui->vrings[msg.state.index]);
+      vlib_worker_thread_barrier_release (vm);
+      vhost_user_update_iface_state (vui);
+      break;
+
+    case VHOST_USER_SET_OWNER:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_OWNER", vui->hw_if_index);
+      break;
+
+    case VHOST_USER_RESET_OWNER:
+      vu_log_debug (vui, "if %d msg VHOST_USER_RESET_OWNER",
+		    vui->hw_if_index);
+      break;
+
+    case VHOST_USER_SET_VRING_CALL:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_VRING_CALL %d",
+		    vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+      if (vui->num_qid > q)
+	{
+	  /* if there is old fd, delete and close it */
+	  if (vui->vrings[q].callfd_idx != ~0)
+	    {
+	      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
+						   vui->vrings[q].callfd_idx);
+	      clib_file_del (&file_main, uf);
+	      vui->vrings[q].callfd_idx = ~0;
+	    }
+	}
+      else if (vec_len (vui->vrings) > q)
+	{
+	  /* grow vrings by pair (RX + TX) */
+	  vui->num_qid = (q & 1) ? (q + 1) : (q + 2);
+	}
+      else
+	{
+	  u32 i, new_max_q, old_max_q = vec_len (vui->vrings);
+
+	  /*
+	   * Double the array size if it is less than 64 entries.
+	   * Slow down thereafter.
+	   */
+	  if (vec_len (vui->vrings) < (VHOST_VRING_INIT_MQ_PAIR_SZ << 3))
+	    new_max_q = vec_len (vui->vrings) << 1;
+	  else
+	    new_max_q = vec_len (vui->vrings) +
+	      (VHOST_VRING_INIT_MQ_PAIR_SZ << 2);
+	  if (new_max_q > (VHOST_VRING_MAX_MQ_PAIR_SZ << 1))
+	    new_max_q = (VHOST_VRING_MAX_MQ_PAIR_SZ << 1);
+
+	  /* sync with the worker threads, vrings may move due to realloc */
+	  vlib_worker_thread_barrier_sync (vm);
+	  vec_validate_aligned (vui->vrings, new_max_q - 1,
+				CLIB_CACHE_LINE_BYTES);
+	  vlib_worker_thread_barrier_release (vm);
+
+	  for (i = old_max_q; i < vec_len (vui->vrings); i++)
+	    vhost_user_vring_init (vui, i);
+
+	  /* grow vrings by pair (RX + TX) */
+	  vui->num_qid = (q & 1) ? (q + 1) : (q + 2);
+	}
+
+      if (!(msg.u64 & VHOST_USER_VRING_NOFD_MASK))
+	{
+	  if (number_of_fds != 1)
+	    {
+	      vu_log_debug (vui, "More than one fd received !");
+	      goto close_socket;
+	    }
+
+	  template.read_function = vhost_user_callfd_read_ready;
+	  template.file_descriptor = fds[0];
+	  template.private_data =
+	    ((vui - vhost_user_main.vhost_user_interfaces) << 8) + q;
+	  template.description = format (0, "vhost user");
+	  vui->vrings[q].callfd_idx = clib_file_add (&file_main, &template);
+	}
+      else
+	vui->vrings[q].callfd_idx = ~0;
+      break;
+
+    case VHOST_USER_SET_VRING_KICK:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_VRING_KICK %d",
+		    vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+      if (q >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring index VHOST_USER_SET_VRING_KICK:"
+			" %u >= %u", q, vui->num_qid);
+	  goto close_socket;
+	}
+
+      if (vui->vrings[q].kickfd_idx != ~0)
+	{
+	  clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
+					       vui->vrings[q].kickfd_idx);
+	  clib_file_del (&file_main, uf);
+	  vui->vrings[q].kickfd_idx = ~0;
+	}
+
+      if (!(msg.u64 & VHOST_USER_VRING_NOFD_MASK))
+	{
+	  if (number_of_fds != 1)
+	    {
+	      vu_log_debug (vui, "More than one fd received !");
+	      goto close_socket;
+	    }
+
+	  template.read_function = vhost_user_kickfd_read_ready;
+	  template.file_descriptor = fds[0];
+	  template.private_data =
+	    (((uword) (vui - vhost_user_main.vhost_user_interfaces)) << 8) +
+	    q;
+	  vui->vrings[q].kickfd_idx = clib_file_add (&file_main, &template);
+	}
+      else
+	{
+	  //When no kickfd is set, the queue is initialized as started
+	  vui->vrings[q].kickfd_idx = ~0;
+	  vui->vrings[q].started = 1;
+	  vhost_user_thread_placement (vui, q);
+	}
+      vhost_user_update_iface_state (vui);
+      break;
+
+    case VHOST_USER_SET_VRING_ERR:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_VRING_ERR %d",
+		    vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+      if (q >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring index VHOST_USER_SET_VRING_ERR:"
+			" %u >= %u", q, vui->num_qid);
+	  goto close_socket;
+	}
+
+      if (vui->vrings[q].errfd != -1)
+	close (vui->vrings[q].errfd);
+
+      if (!(msg.u64 & VHOST_USER_VRING_NOFD_MASK))
+	{
+	  if (number_of_fds != 1)
+	    goto close_socket;
+
+	  vui->vrings[q].errfd = fds[0];
+	}
+      else
+	vui->vrings[q].errfd = -1;
+      break;
+
+    case VHOST_USER_SET_VRING_BASE:
+      vu_log_debug (vui,
+		    "if %d msg VHOST_USER_SET_VRING_BASE idx %d num 0x%x",
+		    vui->hw_if_index, msg.state.index, msg.state.num);
+      if (msg.state.index >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring index VHOST_USER_SET_VRING_ADDR:"
+			" %u >= %u", msg.state.index, vui->num_qid);
+	  goto close_socket;
+	}
+      vlib_worker_thread_barrier_sync (vm);
+      vui->vrings[msg.state.index].last_avail_idx = msg.state.num;
+      if (vhost_user_is_packed_ring_supported (vui))
+	{
+	  /*
+	   *  0                   1                   2                   3
+	   *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+	   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   * |    last avail idx           | |     last used idx           | |
+	   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	   *                                ^                               ^
+	   *                                |                               |
+	   *                         avail wrap counter       used wrap counter
+	   */
+	  /* last avail idx at bit 0-14. */
+	  vui->vrings[msg.state.index].last_avail_idx =
+	    msg.state.num & 0x7fff;
+	  /* avail wrap counter at bit 15 */
+	  vui->vrings[msg.state.index].avail_wrap_counter =
+	    ! !(msg.state.num & (1 << 15));
+
+	  /*
+	   * Although last_used_idx is passed in the upper 16 bits in qemu
+	   * implementation, in practice, last_avail_idx and last_used_idx are
+	   * usually the same. As a result, DPDK does not bother to pass us
+	   * last_used_idx. The spec is not clear on thex coding. I figured it
+	   * out by reading the qemu code. So let's just read last_avail_idx
+	   * and set last_used_idx equals to last_avail_idx.
+	   */
+	  vui->vrings[msg.state.index].last_used_idx =
+	    vui->vrings[msg.state.index].last_avail_idx;
+	  vui->vrings[msg.state.index].last_kick =
+	    vui->vrings[msg.state.index].last_used_idx;
+	  vui->vrings[msg.state.index].used_wrap_counter =
+	    vui->vrings[msg.state.index].avail_wrap_counter;
+
+	  if (vui->vrings[msg.state.index].avail_wrap_counter == 1)
+	    vui->vrings[msg.state.index].avail_wrap_counter =
+	      VRING_DESC_F_AVAIL;
+	}
+      vlib_worker_thread_barrier_release (vm);
+      break;
+
+    case VHOST_USER_GET_VRING_BASE:
+      if (msg.state.index >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring index VHOST_USER_GET_VRING_BASE:"
+			" %u >= %u", msg.state.index, vui->num_qid);
+	  goto close_socket;
+	}
+
+      /* protection is needed to prevent rx/tx from changing last_avail_idx */
+      vlib_worker_thread_barrier_sync (vm);
+      /*
+       * Copy last_avail_idx from the vring before closing it because
+       * closing the vring also initializes the vring last_avail_idx
+       */
+      msg.state.num = vui->vrings[msg.state.index].last_avail_idx;
+      if (vhost_user_is_packed_ring_supported (vui))
+	{
+	  msg.state.num =
+	    (vui->vrings[msg.state.index].last_avail_idx & 0x7fff) |
+	    (! !vui->vrings[msg.state.index].avail_wrap_counter << 15);
+	  msg.state.num |=
+	    ((vui->vrings[msg.state.index].last_used_idx & 0x7fff) |
+	     (! !vui->vrings[msg.state.index].used_wrap_counter << 15)) << 16;
+	}
+      msg.flags |= 4;
+      msg.size = sizeof (msg.state);
+
+      /*
+       * Spec says: Client must [...] stop ring upon receiving
+       * VHOST_USER_GET_VRING_BASE
+       */
+      vhost_user_vring_close (vui, msg.state.index);
+      vlib_worker_thread_barrier_release (vm);
+      vu_log_debug (vui,
+		    "if %d msg VHOST_USER_GET_VRING_BASE idx %d num 0x%x",
+		    vui->hw_if_index, msg.state.index, msg.state.num);
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  vu_log_debug (vui, "could not send message response");
+	  goto close_socket;
+	}
+      vhost_user_update_iface_state (vui);
+      break;
+
+    case VHOST_USER_NONE:
+      vu_log_debug (vui, "if %d msg VHOST_USER_NONE", vui->hw_if_index);
+      break;
+
+    case VHOST_USER_SET_LOG_BASE:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_LOG_BASE",
+		    vui->hw_if_index);
+
+      if (msg.size != sizeof (msg.log))
+	{
+	  vu_log_debug (vui, "invalid msg size for VHOST_USER_SET_LOG_BASE:"
+			" %d instead of %d", msg.size, sizeof (msg.log));
+	  goto close_socket;
+	}
+
+      if (!(vui->protocol_features & (1 << VHOST_USER_PROTOCOL_F_LOG_SHMFD)))
+	{
+	  vu_log_debug (vui, "VHOST_USER_PROTOCOL_F_LOG_SHMFD not set but "
+			"VHOST_USER_SET_LOG_BASE received");
+	  goto close_socket;
+	}
+
+      fd = fds[0];
+      /* align size to page */
+      long page_sz = get_huge_page_size (fd);
+      ssize_t map_sz =
+	(msg.log.size + msg.log.offset + page_sz - 1) & ~(page_sz - 1);
+
+      void *log_base_addr = mmap (0, map_sz, PROT_READ | PROT_WRITE,
+				  MAP_SHARED, fd, 0);
+
+      vu_log_debug (vui, "map log region addr 0 len 0x%lx off 0x%lx fd %d "
+		    "mapped 0x%lx", map_sz, msg.log.offset, fd,
+		    log_base_addr);
+
+      if (log_base_addr == MAP_FAILED)
+	{
+	  vu_log_err (vui, "failed to map memory. errno is %d", errno);
+	  goto close_socket;
+	}
+
+      vlib_worker_thread_barrier_sync (vm);
+      vui->log_base_addr = log_base_addr;
+      vui->log_base_addr += msg.log.offset;
+      vui->log_size = msg.log.size;
+      vlib_worker_thread_barrier_release (vm);
+
+      msg.flags |= 4;
+      msg.size = sizeof (msg.u64);
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  vu_log_debug (vui, "could not send message response");
+	  goto close_socket;
+	}
+      break;
+
+    case VHOST_USER_SET_LOG_FD:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_LOG_FD", vui->hw_if_index);
+      break;
+
+    case VHOST_USER_GET_PROTOCOL_FEATURES:
+      msg.flags |= 4;
+      msg.u64 = (1 << VHOST_USER_PROTOCOL_F_LOG_SHMFD) |
+	(1 << VHOST_USER_PROTOCOL_F_MQ);
+      msg.size = sizeof (msg.u64);
+      vu_log_debug (vui, "if %d msg VHOST_USER_GET_PROTOCOL_FEATURES - "
+		    "reply 0x%016llx", vui->hw_if_index, msg.u64);
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  vu_log_debug (vui, "could not send message response");
+	  goto close_socket;
+	}
+      break;
+
+    case VHOST_USER_SET_PROTOCOL_FEATURES:
+      vu_log_debug (vui, "if %d msg VHOST_USER_SET_PROTOCOL_FEATURES "
+		    "features 0x%016llx", vui->hw_if_index, msg.u64);
+      vui->protocol_features = msg.u64;
+      break;
+
+    case VHOST_USER_GET_QUEUE_NUM:
+      msg.flags |= 4;
+      msg.u64 = VHOST_VRING_MAX_MQ_PAIR_SZ;
+      msg.size = sizeof (msg.u64);
+      vu_log_debug (vui, "if %d msg VHOST_USER_GET_QUEUE_NUM - reply %d",
+		    vui->hw_if_index, msg.u64);
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  vu_log_debug (vui, "could not send message response");
+	  goto close_socket;
+	}
+      break;
+
+    case VHOST_USER_SET_VRING_ENABLE:
+      vu_log_debug (vui, "if %d VHOST_USER_SET_VRING_ENABLE: %s queue %d",
+		    vui->hw_if_index, msg.state.num ? "enable" : "disable",
+		    msg.state.index);
+      if (msg.state.index >= vui->num_qid)
+	{
+	  vu_log_debug (vui, "invalid vring idx VHOST_USER_SET_VRING_ENABLE:"
+			" %u >= %u", msg.state.index, vui->num_qid);
+	  goto close_socket;
+	}
+
+      vui->vrings[msg.state.index].enabled = msg.state.num;
+      vhost_user_thread_placement (vui, msg.state.index);
+      vhost_user_update_iface_state (vui);
+      break;
+
+    default:
+      vu_log_debug (vui, "unknown vhost-user message %d received. "
+		    "closing socket", msg.request);
+      goto close_socket;
+    }
+
+  return 0;
+
+close_socket:
+  vlib_worker_thread_barrier_sync (vm);
+  vhost_user_if_disconnect (vui);
+  vlib_worker_thread_barrier_release (vm);
+  vhost_user_update_iface_state (vui);
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_socket_error (clib_file_t * uf)
+{
+  vlib_main_t *vm = vlib_get_main ();
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data);
+
+  vu_log_debug (vui, "socket error on if %d", vui->sw_if_index);
+  vlib_worker_thread_barrier_sync (vm);
+  vhost_user_if_disconnect (vui);
+  vlib_worker_thread_barrier_release (vm);
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_socksvr_accept_ready (clib_file_t * uf)
+{
+  int client_fd, client_len;
+  struct sockaddr_un client;
+  clib_file_t template = { 0 };
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data);
+
+  client_len = sizeof (client);
+  client_fd = accept (uf->file_descriptor,
+		      (struct sockaddr *) &client,
+		      (socklen_t *) & client_len);
+
+  if (client_fd < 0)
+    return clib_error_return_unix (0, "accept");
+
+  if (vui->clib_file_index != ~0)
+    {
+      vu_log_debug (vui, "Close client socket for vhost interface %d, fd %d",
+		    vui->sw_if_index, UNIX_GET_FD (vui->clib_file_index));
+      clib_file_del (&file_main, file_main.file_pool + vui->clib_file_index);
+    }
+
+  vu_log_debug (vui, "New client socket for vhost interface %d, fd %d",
+		vui->sw_if_index, client_fd);
+  template.read_function = vhost_user_socket_read;
+  template.error_function = vhost_user_socket_error;
+  template.file_descriptor = client_fd;
+  template.private_data = vui - vhost_user_main.vhost_user_interfaces;
+  template.description = format (0, "vhost interface %d", vui->sw_if_index);
+  vui->clib_file_index = clib_file_add (&file_main, &template);
+  vui->num_qid = 2;
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_init (vlib_main_t * vm)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+
+  vum->log_default = vlib_log_register_class ("vhost-user", 0);
+
+  vum->coalesce_frames = 32;
+  vum->coalesce_time = 1e-3;
+
+  vec_validate (vum->cpus, tm->n_vlib_mains - 1);
+
+  vhost_cpu_t *cpu;
+  vec_foreach (cpu, vum->cpus)
+  {
+    /* This is actually not necessary as validate already zeroes it
+     * Just keeping the loop here for later because I am lazy. */
+    cpu->rx_buffers_len = 0;
+  }
+
+  vum->random = random_default_seed ();
+
+  mhash_init_c_string (&vum->if_index_by_sock_name, sizeof (uword));
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_INIT_FUNCTION (vhost_user_init) =
+{
+  .runs_after = VLIB_INITS("ip4_init"),
+};
+/* *INDENT-ON* */
+
+static uword
+vhost_user_send_interrupt_process (vlib_main_t * vm,
+				   vlib_node_runtime_t * rt, vlib_frame_t * f)
+{
+  vhost_user_intf_t *vui;
+  f64 timeout = 3153600000.0 /* 100 years */ ;
+  uword event_type, *event_data = 0;
+  vhost_user_main_t *vum = &vhost_user_main;
+  u16 qid;
+  f64 now, poll_time_remaining;
+  f64 next_timeout;
+  u8 stop_timer = 0;
+
+  while (1)
+    {
+      poll_time_remaining =
+	vlib_process_wait_for_event_or_clock (vm, timeout);
+      event_type = vlib_process_get_events (vm, &event_data);
+      vec_reset_length (event_data);
+
+      /*
+       * Use the remaining timeout if it is less than coalesce time to avoid
+       * resetting the existing timer in the middle of expiration
+       */
+      timeout = poll_time_remaining;
+      if (vlib_process_suspend_time_is_zero (timeout) ||
+	  (timeout > vum->coalesce_time))
+	timeout = vum->coalesce_time;
+
+      now = vlib_time_now (vm);
+      switch (event_type)
+	{
+	case VHOST_USER_EVENT_STOP_TIMER:
+	  stop_timer = 1;
+	  break;
+
+	case VHOST_USER_EVENT_START_TIMER:
+	  stop_timer = 0;
+	  timeout = 1e-3;
+	  if (!vlib_process_suspend_time_is_zero (poll_time_remaining))
+	    break;
+	  /* fall through */
+
+	case ~0:
+	  /* *INDENT-OFF* */
+	  pool_foreach (vui, vum->vhost_user_interfaces) {
+	      next_timeout = timeout;
+	      FOR_ALL_VHOST_RX_TXQ (qid, vui)
+	      {
+		vhost_user_vring_t *vq = &vui->vrings[qid];
+
+		if (vq->started == 0)
+		  continue;
+		if (vq->n_since_last_int)
+		  {
+		    if (now >= vq->int_deadline)
+		      vhost_user_send_call (vm, vui, vq);
+		    else
+		      next_timeout = vq->int_deadline - now;
+		  }
+
+		if ((next_timeout < timeout) && (next_timeout > 0.0))
+		  timeout = next_timeout;
+	      }
+	  }
+          /* *INDENT-ON* */
+	  break;
+
+	default:
+	  clib_warning ("BUG: unhandled event type %d", event_type);
+	  break;
+	}
+      /* No less than 1 millisecond */
+      if (timeout < 1e-3)
+	timeout = 1e-3;
+      if (stop_timer)
+	timeout = 3153600000.0;
+    }
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (vhost_user_send_interrupt_node) = {
+    .function = vhost_user_send_interrupt_process,
+    .type = VLIB_NODE_TYPE_PROCESS,
+    .name = "vhost-user-send-interrupt-process",
+};
+/* *INDENT-ON* */
+
+static uword
+vhost_user_process (vlib_main_t * vm,
+		    vlib_node_runtime_t * rt, vlib_frame_t * f)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  struct sockaddr_un sun;
+  int sockfd;
+  clib_file_t template = { 0 };
+  f64 timeout = 3153600000.0 /* 100 years */ ;
+  uword *event_data = 0;
+
+  sockfd = -1;
+  sun.sun_family = AF_UNIX;
+  template.read_function = vhost_user_socket_read;
+  template.error_function = vhost_user_socket_error;
+
+  while (1)
+    {
+      vlib_process_wait_for_event_or_clock (vm, timeout);
+      vlib_process_get_events (vm, &event_data);
+      vec_reset_length (event_data);
+
+      timeout = 3.0;
+
+      /* *INDENT-OFF* */
+      pool_foreach (vui, vum->vhost_user_interfaces) {
+
+	  if (vui->unix_server_index == ~0) { //Nothing to do for server sockets
+	      if (vui->clib_file_index == ~0)
+		{
+		  if ((sockfd < 0) &&
+		      ((sockfd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0))
+		    {
+		      /*
+		       * 1st time error or new error for this interface,
+		       * spit out the message and record the error
+		       */
+		      if (!vui->sock_errno || (vui->sock_errno != errno))
+			{
+			  clib_unix_warning
+			    ("Error: Could not open unix socket for %s",
+			     vui->sock_filename);
+			  vui->sock_errno = errno;
+			}
+		      continue;
+		    }
+
+		  /* try to connect */
+		  strncpy (sun.sun_path, (char *) vui->sock_filename,
+			   sizeof (sun.sun_path) - 1);
+		  sun.sun_path[sizeof (sun.sun_path) - 1] = 0;
+
+		  /* Avoid hanging VPP if the other end does not accept */
+		  if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0)
+                      clib_unix_warning ("fcntl");
+
+		  if (connect (sockfd, (struct sockaddr *) &sun,
+			       sizeof (struct sockaddr_un)) == 0)
+		    {
+		      /* Set the socket to blocking as it was before */
+                      if (fcntl(sockfd, F_SETFL, 0) < 0)
+                        clib_unix_warning ("fcntl2");
+
+		      vui->sock_errno = 0;
+		      template.file_descriptor = sockfd;
+		      template.private_data =
+			  vui - vhost_user_main.vhost_user_interfaces;
+		      template.description = format (0, "vhost user process");
+		      vui->clib_file_index = clib_file_add (&file_main, &template);
+		      vui->num_qid = 2;
+
+		      /* This sockfd is considered consumed */
+		      sockfd = -1;
+		    }
+		  else
+		    {
+		      vui->sock_errno = errno;
+		    }
+		}
+	      else
+		{
+		  /* check if socket is alive */
+		  int error = 0;
+		  socklen_t len = sizeof (error);
+		  int fd = UNIX_GET_FD(vui->clib_file_index);
+		  int retval =
+		      getsockopt (fd, SOL_SOCKET, SO_ERROR, &error, &len);
+
+		  if (retval)
+		    {
+		      vu_log_debug (vui, "getsockopt returned %d", retval);
+		      vhost_user_if_disconnect (vui);
+		    }
+		}
+	  }
+      }
+      /* *INDENT-ON* */
+    }
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (vhost_user_process_node,static) = {
+    .function = vhost_user_process,
+    .type = VLIB_NODE_TYPE_PROCESS,
+    .name = "vhost-user-process",
+};
+/* *INDENT-ON* */
+
+/**
+ * Disables and reset interface structure.
+ * It can then be either init again, or removed from used interfaces.
+ */
+static void
+vhost_user_term_if (vhost_user_intf_t * vui)
+{
+  int q;
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  // disconnect interface sockets
+  vhost_user_if_disconnect (vui);
+  vhost_user_update_gso_interface_count (vui, 0 /* delete */ );
+  vhost_user_update_iface_state (vui);
+
+  for (q = 0; q < vec_len (vui->vrings); q++)
+    clib_spinlock_free (&vui->vrings[q].vring_lock);
+
+  if (vui->unix_server_index != ~0)
+    {
+      //Close server socket
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
+					   vui->unix_server_index);
+      clib_file_del (&file_main, uf);
+      vui->unix_server_index = ~0;
+      unlink (vui->sock_filename);
+    }
+
+  mhash_unset (&vum->if_index_by_sock_name, vui->sock_filename,
+	       &vui->if_index);
+}
+
+int
+vhost_user_delete_if (vnet_main_t * vnm, vlib_main_t * vm, u32 sw_if_index)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  int rv = 0;
+  vnet_hw_interface_t *hwif;
+  u16 qid;
+
+  if (!
+      (hwif =
+       vnet_get_sup_hw_interface_api_visible_or_null (vnm, sw_if_index))
+      || hwif->dev_class_index != vhost_user_device_class.index)
+    return VNET_API_ERROR_INVALID_SW_IF_INDEX;
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, hwif->dev_instance);
+
+  vu_log_debug (vui, "Deleting vhost-user interface %s (instance %d)",
+		hwif->name, hwif->dev_instance);
+
+  FOR_ALL_VHOST_TXQ (qid, vui)
+  {
+    vhost_user_vring_t *txvq = &vui->vrings[qid];
+
+    if ((txvq->mode == VNET_HW_IF_RX_MODE_POLLING) &&
+	(txvq->thread_index != ~0))
+      {
+	vhost_cpu_t *cpu = vec_elt_at_index (vum->cpus, txvq->thread_index);
+	ASSERT (cpu->polling_q_count != 0);
+	cpu->polling_q_count--;
+      }
+
+    if ((vum->ifq_count > 0) &&
+	((txvq->mode == VNET_HW_IF_RX_MODE_INTERRUPT) ||
+	 (txvq->mode == VNET_HW_IF_RX_MODE_ADAPTIVE)))
+      {
+	vum->ifq_count--;
+	// Stop the timer if there is no more interrupt interface/queue
+	if (vum->ifq_count == 0)
+	  {
+	    vlib_process_signal_event (vm,
+				       vhost_user_send_interrupt_node.index,
+				       VHOST_USER_EVENT_STOP_TIMER, 0);
+	    break;
+	  }
+      }
+  }
+
+  // Disable and reset interface
+  vhost_user_term_if (vui);
+
+  // Reset renumbered iface
+  if (hwif->dev_instance <
+      vec_len (vum->show_dev_instance_by_real_dev_instance))
+    vum->show_dev_instance_by_real_dev_instance[hwif->dev_instance] = ~0;
+
+  // Delete ethernet interface
+  ethernet_delete_interface (vnm, vui->hw_if_index);
+
+  // free vrings
+  vec_free (vui->vrings);
+
+  // Back to pool
+  pool_put (vum->vhost_user_interfaces, vui);
+
+  return rv;
+}
+
+static clib_error_t *
+vhost_user_exit (vlib_main_t * vm)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+
+  vlib_worker_thread_barrier_sync (vlib_get_main ());
+  /* *INDENT-OFF* */
+  pool_foreach (vui, vum->vhost_user_interfaces) {
+      vhost_user_delete_if (vnm, vm, vui->sw_if_index);
+  }
+  /* *INDENT-ON* */
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+  return 0;
+}
+
+VLIB_MAIN_LOOP_EXIT_FUNCTION (vhost_user_exit);
+
+/**
+ * Open server unix socket on specified sock_filename.
+ */
+static int
+vhost_user_init_server_sock (const char *sock_filename, int *sock_fd)
+{
+  int rv = 0;
+  struct sockaddr_un un = { };
+  int fd;
+  /* create listening socket */
+  if ((fd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
+    return VNET_API_ERROR_SYSCALL_ERROR_1;
+
+  un.sun_family = AF_UNIX;
+  strncpy ((char *) un.sun_path, (char *) sock_filename,
+	   sizeof (un.sun_path) - 1);
+
+  /* remove if exists */
+  unlink ((char *) sock_filename);
+
+  if (bind (fd, (struct sockaddr *) &un, sizeof (un)) == -1)
+    {
+      rv = VNET_API_ERROR_SYSCALL_ERROR_2;
+      goto error;
+    }
+
+  if (listen (fd, 1) == -1)
+    {
+      rv = VNET_API_ERROR_SYSCALL_ERROR_3;
+      goto error;
+    }
+
+  *sock_fd = fd;
+  return 0;
+
+error:
+  close (fd);
+  return rv;
+}
+
+/**
+ * Create ethernet interface for vhost user interface.
+ */
+static void
+vhost_user_create_ethernet (vnet_main_t *vnm, vlib_main_t *vm,
+			    vhost_user_intf_t *vui,
+			    vhost_user_create_if_args_t *args)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vnet_eth_interface_registration_t eir = {};
+  u8 hwaddr[6];
+
+  /* create hw and sw interface */
+  if (args->use_custom_mac)
+    {
+      clib_memcpy (hwaddr, args->hwaddr, 6);
+    }
+  else
+    {
+      random_u32 (&vum->random);
+      clib_memcpy (hwaddr + 2, &vum->random, sizeof (vum->random));
+      hwaddr[0] = 2;
+      hwaddr[1] = 0xfe;
+    }
+
+  eir.dev_class_index = vhost_user_device_class.index;
+  eir.dev_instance = vui - vum->vhost_user_interfaces /* device instance */,
+  eir.address = hwaddr;
+  vui->hw_if_index = vnet_eth_register_interface (vnm, &eir);
+}
+
+/*
+ *  Initialize vui with specified attributes
+ */
+static void
+vhost_user_vui_init (vnet_main_t * vnm, vhost_user_intf_t * vui,
+		     int server_sock_fd, vhost_user_create_if_args_t * args,
+		     u32 * sw_if_index)
+{
+  vnet_sw_interface_t *sw;
+  int q;
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  sw = vnet_get_hw_sw_interface (vnm, vui->hw_if_index);
+  if (server_sock_fd != -1)
+    {
+      clib_file_t template = { 0 };
+      template.read_function = vhost_user_socksvr_accept_ready;
+      template.file_descriptor = server_sock_fd;
+      template.private_data = vui - vum->vhost_user_interfaces;	//hw index
+      template.description = format (0, "vhost user %d", sw);
+      vui->unix_server_index = clib_file_add (&file_main, &template);
+    }
+  else
+    {
+      vui->unix_server_index = ~0;
+    }
+
+  vui->sw_if_index = sw->sw_if_index;
+  strncpy (vui->sock_filename, args->sock_filename,
+	   ARRAY_LEN (vui->sock_filename) - 1);
+  vui->sock_errno = 0;
+  vui->is_ready = 0;
+  vui->feature_mask = args->feature_mask;
+  vui->clib_file_index = ~0;
+  vui->log_base_addr = 0;
+  vui->if_index = vui - vum->vhost_user_interfaces;
+  vui->enable_gso = args->enable_gso;
+  vui->enable_event_idx = args->enable_event_idx;
+  vui->enable_packed = args->enable_packed;
+  /*
+   * enable_gso takes precedence over configurable feature mask if there
+   * is a clash.
+   *   if feature mask disables gso, but enable_gso is configured,
+   *     then gso is enable
+   *   if feature mask enables gso, but enable_gso is not configured,
+   *     then gso is enable
+   *
+   * if gso is enable via feature mask, it must enable both host and guest
+   * gso feature mask, we don't support one sided GSO or partial GSO.
+   */
+  if ((vui->enable_gso == 0) &&
+      ((args->feature_mask & FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS)
+       == (FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS)))
+    vui->enable_gso = 1;
+  vhost_user_update_gso_interface_count (vui, 1 /* add */ );
+  mhash_set_mem (&vum->if_index_by_sock_name, vui->sock_filename,
+		 &vui->if_index, 0);
+
+  vec_validate_aligned (vui->vrings, (VHOST_VRING_INIT_MQ_PAIR_SZ << 1) - 1,
+			CLIB_CACHE_LINE_BYTES);
+  vui->num_qid = 2;
+  for (q = 0; q < vec_len (vui->vrings); q++)
+    vhost_user_vring_init (vui, q);
+
+  vnet_hw_if_set_caps (vnm, vui->hw_if_index, VNET_HW_IF_CAP_INT_MODE);
+  vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
+
+  if (sw_if_index)
+    *sw_if_index = vui->sw_if_index;
+}
+
+int
+vhost_user_create_if (vnet_main_t * vnm, vlib_main_t * vm,
+		      vhost_user_create_if_args_t * args)
+{
+  vhost_user_intf_t *vui = NULL;
+  u32 sw_if_idx = ~0;
+  int rv = 0;
+  int server_sock_fd = -1;
+  vhost_user_main_t *vum = &vhost_user_main;
+  uword *if_index;
+
+  if (args->sock_filename == NULL || !(strlen (args->sock_filename) > 0))
+    {
+      return VNET_API_ERROR_INVALID_ARGUMENT;
+    }
+
+  if_index = mhash_get (&vum->if_index_by_sock_name,
+			(void *) args->sock_filename);
+  if (if_index)
+    {
+      vui = &vum->vhost_user_interfaces[*if_index];
+      args->sw_if_index = vui->sw_if_index;
+      return VNET_API_ERROR_IF_ALREADY_EXISTS;
+    }
+
+  if (args->is_server)
+    {
+      if ((rv =
+	   vhost_user_init_server_sock (args->sock_filename,
+					&server_sock_fd)) != 0)
+	{
+	  return rv;
+	}
+    }
+
+  /* Protect the uninitialized vui from being dispatched by rx/tx */
+  vlib_worker_thread_barrier_sync (vm);
+  pool_get (vhost_user_main.vhost_user_interfaces, vui);
+  vhost_user_create_ethernet (vnm, vm, vui, args);
+  vlib_worker_thread_barrier_release (vm);
+
+  vhost_user_vui_init (vnm, vui, server_sock_fd, args, &sw_if_idx);
+  vnet_sw_interface_set_mtu (vnm, vui->sw_if_index, 9000);
+  vhost_user_rx_thread_placement (vui, 1);
+
+  if (args->renumber)
+    vnet_interface_name_renumber (sw_if_idx, args->custom_dev_instance);
+
+  args->sw_if_index = sw_if_idx;
+
+  // Process node must connect
+  vlib_process_signal_event (vm, vhost_user_process_node.index, 0, 0);
+
+  return rv;
+}
+
+int
+vhost_user_modify_if (vnet_main_t * vnm, vlib_main_t * vm,
+		      vhost_user_create_if_args_t * args)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui = NULL;
+  u32 sw_if_idx = ~0;
+  int server_sock_fd = -1;
+  int rv = 0;
+  vnet_hw_interface_t *hwif;
+  uword *if_index;
+
+  if (!(hwif = vnet_get_sup_hw_interface_api_visible_or_null (vnm,
+							      args->sw_if_index))
+      || hwif->dev_class_index != vhost_user_device_class.index)
+    return VNET_API_ERROR_INVALID_SW_IF_INDEX;
+
+  if (args->sock_filename == NULL || !(strlen (args->sock_filename) > 0))
+    return VNET_API_ERROR_INVALID_ARGUMENT;
+
+  vui = vec_elt_at_index (vum->vhost_user_interfaces, hwif->dev_instance);
+
+  /*
+   * Disallow changing the interface to have the same path name
+   * as other interface
+   */
+  if_index = mhash_get (&vum->if_index_by_sock_name,
+			(void *) args->sock_filename);
+  if (if_index && (*if_index != vui->if_index))
+    return VNET_API_ERROR_IF_ALREADY_EXISTS;
+
+  // First try to open server socket
+  if (args->is_server)
+    if ((rv = vhost_user_init_server_sock (args->sock_filename,
+					   &server_sock_fd)) != 0)
+      return rv;
+
+  vhost_user_term_if (vui);
+  vhost_user_vui_init (vnm, vui, server_sock_fd, args, &sw_if_idx);
+
+  if (args->renumber)
+    vnet_interface_name_renumber (sw_if_idx, args->custom_dev_instance);
+
+  // Process node must connect
+  vlib_process_signal_event (vm, vhost_user_process_node.index, 0, 0);
+
+  return rv;
+}
+
+clib_error_t *
+vhost_user_connect_command_fn (vlib_main_t * vm,
+			       unformat_input_t * input,
+			       vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  unformat_input_t _line_input, *line_input = &_line_input;
+  clib_error_t *error = NULL;
+  vhost_user_create_if_args_t args = { 0 };
+  int rv;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  args.feature_mask = (u64) ~ (0ULL);
+  args.custom_dev_instance = ~0;
+  /* GSO feature is disable by default */
+  args.feature_mask &= ~FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS;
+  /* packed-ring feature is disable by default */
+  args.feature_mask &= ~VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+  /* event_idx feature is disable by default */
+  args.feature_mask &= ~VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "socket %s", &args.sock_filename))
+	;
+      else if (unformat (line_input, "server"))
+	args.is_server = 1;
+      else if (unformat (line_input, "gso"))
+	args.enable_gso = 1;
+      else if (unformat (line_input, "packed"))
+	args.enable_packed = 1;
+      else if (unformat (line_input, "event-idx"))
+	args.enable_event_idx = 1;
+      else if (unformat (line_input, "feature-mask 0x%llx",
+			 &args.feature_mask))
+	;
+      else if (unformat (line_input, "hwaddr %U", unformat_ethernet_address,
+			 args.hwaddr))
+	args.use_custom_mac = 1;
+      else if (unformat (line_input, "renumber %d",
+			 &args.custom_dev_instance))
+	args.renumber = 1;
+      else
+	{
+	  error = clib_error_return (0, "unknown input `%U'",
+				     format_unformat_error, line_input);
+	  goto done;
+	}
+    }
+
+  if ((rv = vhost_user_create_if (vnm, vm, &args)))
+    {
+      error = clib_error_return (0, "vhost_user_create_if returned %d", rv);
+      goto done;
+    }
+
+  vlib_cli_output (vm, "%U\n", format_vnet_sw_if_index_name, vnm,
+		   args.sw_if_index);
+
+done:
+  vec_free (args.sock_filename);
+  unformat_free (line_input);
+
+  return error;
+}
+
+clib_error_t *
+vhost_user_delete_command_fn (vlib_main_t * vm,
+			      unformat_input_t * input,
+			      vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  u32 sw_if_index = ~0;
+  vnet_main_t *vnm = vnet_get_main ();
+  clib_error_t *error = NULL;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "sw_if_index %d", &sw_if_index))
+	;
+      else if (unformat
+	       (line_input, "%U", unformat_vnet_sw_interface, vnm,
+		&sw_if_index))
+	{
+	  vnet_hw_interface_t *hwif =
+	    vnet_get_sup_hw_interface_api_visible_or_null (vnm, sw_if_index);
+	  if (hwif == NULL ||
+	      vhost_user_device_class.index != hwif->dev_class_index)
+	    {
+	      error = clib_error_return (0, "Not a vhost interface");
+	      goto done;
+	    }
+	}
+      else
+	{
+	  error = clib_error_return (0, "unknown input `%U'",
+				     format_unformat_error, line_input);
+	  goto done;
+	}
+    }
+
+  vhost_user_delete_if (vnm, vm, sw_if_index);
+
+done:
+  unformat_free (line_input);
+
+  return error;
+}
+
+int
+vhost_user_dump_ifs (vnet_main_t * vnm, vlib_main_t * vm,
+		     vhost_user_intf_details_t ** out_vuids)
+{
+  int rv = 0;
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  vhost_user_intf_details_t *r_vuids = NULL;
+  vhost_user_intf_details_t *vuid = NULL;
+  u32 *hw_if_indices = 0;
+  vnet_hw_interface_t *hi;
+  int i;
+
+  if (!out_vuids)
+    return -1;
+
+  pool_foreach (vui, vum->vhost_user_interfaces)
+    vec_add1 (hw_if_indices, vui->hw_if_index);
+
+  for (i = 0; i < vec_len (hw_if_indices); i++)
+    {
+      hi = vnet_get_hw_interface (vnm, hw_if_indices[i]);
+      vui = pool_elt_at_index (vum->vhost_user_interfaces, hi->dev_instance);
+
+      vec_add2 (r_vuids, vuid, 1);
+      vuid->sw_if_index = vui->sw_if_index;
+      vuid->virtio_net_hdr_sz = vui->virtio_net_hdr_sz;
+      vuid->features = vui->features;
+      vuid->num_regions = vui->nregions;
+      vuid->is_server = vui->unix_server_index != ~0;
+      vuid->sock_errno = vui->sock_errno;
+      snprintf ((char *) vuid->sock_filename, sizeof (vuid->sock_filename),
+		"%s", vui->sock_filename);
+      memcpy_s (vuid->if_name, sizeof (vuid->if_name), hi->name,
+		clib_min (vec_len (hi->name), sizeof (vuid->if_name) - 1));
+      vuid->if_name[sizeof (vuid->if_name) - 1] = 0;
+    }
+
+  vec_free (hw_if_indices);
+
+  *out_vuids = r_vuids;
+
+  return rv;
+}
+
+static u8 *
+format_vhost_user_desc (u8 * s, va_list * args)
+{
+  char *fmt = va_arg (*args, char *);
+  vhost_user_intf_t *vui = va_arg (*args, vhost_user_intf_t *);
+  vnet_virtio_vring_desc_t *desc_table =
+    va_arg (*args, vnet_virtio_vring_desc_t *);
+  int idx = va_arg (*args, int);
+  u32 *mem_hint = va_arg (*args, u32 *);
+
+  s = format (s, fmt, idx, desc_table[idx].addr, desc_table[idx].len,
+	      desc_table[idx].flags, desc_table[idx].next,
+	      pointer_to_uword (map_guest_mem (vui, desc_table[idx].addr,
+					       mem_hint)));
+  return s;
+}
+
+static void
+vhost_user_show_fds (vlib_main_t * vm, vhost_user_vring_t * vq)
+{
+  int kickfd = UNIX_GET_FD (vq->kickfd_idx);
+  int callfd = UNIX_GET_FD (vq->callfd_idx);
+
+  vlib_cli_output (vm, "  kickfd %d callfd %d errfd %d\n", kickfd, callfd,
+		   vq->errfd);
+}
+
+static void
+vhost_user_show_desc (vlib_main_t * vm, vhost_user_intf_t * vui, int q,
+		      int show_descr, int show_verbose)
+{
+  int j;
+  u32 mem_hint = 0;
+  u32 idx;
+  u32 n_entries;
+  vnet_virtio_vring_desc_t *desc_table;
+  vhost_user_vring_t *vq = &vui->vrings[q];
+
+  if (vq->avail && vq->used)
+    vlib_cli_output (vm,
+		     "  avail.flags %x avail event idx %u avail.idx %d "
+		     "used.flags %x used event idx %u used.idx %d\n",
+		     vq->avail->flags, vhost_user_avail_event_idx (vq),
+		     vq->avail->idx, vq->used->flags,
+		     vhost_user_used_event_idx (vq), vq->used->idx);
+
+  vhost_user_show_fds (vm, vq);
+
+  if (show_descr)
+    {
+      vlib_cli_output (vm, "\n  descriptor table:\n");
+      vlib_cli_output (vm,
+		       "  slot         addr         len  flags  next      "
+		       "user_addr\n");
+      vlib_cli_output (vm,
+		       "  ===== ================== ===== ====== ===== "
+		       "==================\n");
+      for (j = 0; j < vq->qsz_mask + 1; j++)
+	{
+	  desc_table = vq->desc;
+	  vlib_cli_output (vm, "%U", format_vhost_user_desc,
+			   "  %-5d 0x%016lx %-5d 0x%04x %-5d 0x%016lx\n", vui,
+			   desc_table, j, &mem_hint);
+	  if (show_verbose && (desc_table[j].flags & VRING_DESC_F_INDIRECT))
+	    {
+	      n_entries =
+		desc_table[j].len / sizeof (vnet_virtio_vring_desc_t);
+	      desc_table = map_guest_mem (vui, desc_table[j].addr, &mem_hint);
+	      if (desc_table)
+		{
+		  for (idx = 0; idx < clib_min (20, n_entries); idx++)
+		    {
+		      vlib_cli_output
+			(vm, "%U", format_vhost_user_desc,
+			 ">  %-4u 0x%016lx %-5u 0x%04x %-5u 0x%016lx\n", vui,
+			 desc_table, idx, &mem_hint);
+		    }
+		  if (n_entries >= 20)
+		    vlib_cli_output (vm, "Skip displaying entries 20...%u\n",
+				     n_entries);
+		}
+	    }
+	}
+    }
+}
+
+static u8 *
+format_vhost_user_packed_desc (u8 * s, va_list * args)
+{
+  char *fmt = va_arg (*args, char *);
+  vhost_user_intf_t *vui = va_arg (*args, vhost_user_intf_t *);
+  vnet_virtio_vring_packed_desc_t *desc_table =
+    va_arg (*args, vnet_virtio_vring_packed_desc_t *);
+  int idx = va_arg (*args, int);
+  u32 *mem_hint = va_arg (*args, u32 *);
+
+  s = format (s, fmt, idx, desc_table[idx].addr, desc_table[idx].len,
+	      desc_table[idx].flags, desc_table[idx].id,
+	      pointer_to_uword (map_guest_mem (vui, desc_table[idx].addr,
+					       mem_hint)));
+  return s;
+}
+
+static u8 *
+format_vhost_user_event_idx_flags (u8 * s, va_list * args)
+{
+  u32 flags = va_arg (*args, u32);
+  typedef struct
+  {
+    u8 value;
+    char *str;
+  } event_idx_flags;
+  static event_idx_flags event_idx_array[] = {
+#define _(s,v) { .str = #s, .value = v, },
+    foreach_virtio_event_idx_flags
+#undef _
+  };
+  u32 num_entries = sizeof (event_idx_array) / sizeof (event_idx_flags);
+
+  if (flags < num_entries)
+    s = format (s, "%s", event_idx_array[flags].str);
+  else
+    s = format (s, "%u", flags);
+  return s;
+}
+
+static void
+vhost_user_show_desc_packed (vlib_main_t * vm, vhost_user_intf_t * vui, int q,
+			     int show_descr, int show_verbose)
+{
+  int j;
+  u32 mem_hint = 0;
+  u32 idx;
+  u32 n_entries;
+  vnet_virtio_vring_packed_desc_t *desc_table;
+  vhost_user_vring_t *vq = &vui->vrings[q];
+  u16 off_wrap, event_idx;
+
+  off_wrap = vq->avail_event->off_wrap;
+  event_idx = off_wrap & 0x7fff;
+  vlib_cli_output (vm, "  avail_event.flags %U avail_event.off_wrap %u "
+		   "avail event idx %u\n", format_vhost_user_event_idx_flags,
+		   (u32) vq->avail_event->flags, off_wrap, event_idx);
+
+  off_wrap = vq->used_event->off_wrap;
+  event_idx = off_wrap & 0x7fff;
+  vlib_cli_output (vm, "  used_event.flags %U used_event.off_wrap %u "
+		   "used event idx %u\n", format_vhost_user_event_idx_flags,
+		   (u32) vq->used_event->flags, off_wrap, event_idx);
+
+  vlib_cli_output (vm, "  avail wrap counter %u, used wrap counter %u\n",
+		   vq->avail_wrap_counter, vq->used_wrap_counter);
+
+  vhost_user_show_fds (vm, vq);
+
+  if (show_descr)
+    {
+      vlib_cli_output (vm, "\n  descriptor table:\n");
+      vlib_cli_output (vm,
+		       "  slot         addr         len  flags  id    "
+		       "user_addr\n");
+      vlib_cli_output (vm,
+		       "  ===== ================== ===== ====== ===== "
+		       "==================\n");
+      for (j = 0; j < vq->qsz_mask + 1; j++)
+	{
+	  desc_table = vq->packed_desc;
+	  vlib_cli_output (vm, "%U", format_vhost_user_packed_desc,
+			   "  %-5u 0x%016lx %-5u 0x%04x %-5u 0x%016lx\n", vui,
+			   desc_table, j, &mem_hint);
+	  if (show_verbose && (desc_table[j].flags & VRING_DESC_F_INDIRECT))
+	    {
+	      n_entries = desc_table[j].len >> 4;
+	      desc_table = map_guest_mem (vui, desc_table[j].addr, &mem_hint);
+	      if (desc_table)
+		{
+		  for (idx = 0; idx < clib_min (20, n_entries); idx++)
+		    {
+		      vlib_cli_output
+			(vm, "%U", format_vhost_user_packed_desc,
+			 ">  %-4u 0x%016lx %-5u 0x%04x %-5u 0x%016lx\n", vui,
+			 desc_table, idx, &mem_hint);
+		    }
+		  if (n_entries >= 20)
+		    vlib_cli_output (vm, "Skip displaying entries 20...%u\n",
+				     n_entries);
+		}
+	    }
+	}
+    }
+}
+
+clib_error_t *
+show_vhost_user_command_fn (vlib_main_t * vm,
+			    unformat_input_t * input,
+			    vlib_cli_command_t * cmd)
+{
+  clib_error_t *error = 0;
+  vnet_main_t *vnm = vnet_get_main ();
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  u32 hw_if_index, *hw_if_indices = 0;
+  vnet_hw_interface_t *hi;
+  u16 qid;
+  int i, j, q;
+  int show_descr = 0;
+  int show_verbose = 0;
+  struct feat_struct
+  {
+    u8 bit;
+    char *str;
+  };
+  struct feat_struct *feat_entry;
+
+  static struct feat_struct feat_array[] = {
+#define _(s,b) { .str = #s, .bit = b, },
+    foreach_virtio_net_features
+#undef _
+    {.str = NULL}
+  };
+
+#define foreach_protocol_feature \
+  _(VHOST_USER_PROTOCOL_F_MQ) \
+  _(VHOST_USER_PROTOCOL_F_LOG_SHMFD)
+
+  static struct feat_struct proto_feat_array[] = {
+#define _(s) { .str = #s, .bit = s},
+    foreach_protocol_feature
+#undef _
+    {.str = NULL}
+  };
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat
+	  (input, "%U", unformat_vnet_hw_interface, vnm, &hw_if_index))
+	{
+	  hi = vnet_get_hw_interface (vnm, hw_if_index);
+	  if (vhost_user_device_class.index != hi->dev_class_index)
+	    {
+	      error = clib_error_return (0, "unknown input `%U'",
+					 format_unformat_error, input);
+	      goto done;
+	    }
+	  vec_add1 (hw_if_indices, hw_if_index);
+	}
+      else if (unformat (input, "descriptors") || unformat (input, "desc"))
+	show_descr = 1;
+      else if (unformat (input, "verbose"))
+	show_verbose = 1;
+      else
+	{
+	  error = clib_error_return (0, "unknown input `%U'",
+				     format_unformat_error, input);
+	  goto done;
+	}
+    }
+  if (vec_len (hw_if_indices) == 0)
+    {
+      pool_foreach (vui, vum->vhost_user_interfaces)
+	vec_add1 (hw_if_indices, vui->hw_if_index);
+    }
+  vlib_cli_output (vm, "Virtio vhost-user interfaces");
+  vlib_cli_output (vm, "Global:\n  coalesce frames %d time %e",
+		   vum->coalesce_frames, vum->coalesce_time);
+  vlib_cli_output (vm, "  Number of rx virtqueues in interrupt mode: %d",
+		   vum->ifq_count);
+  vlib_cli_output (vm, "  Number of GSO interfaces: %d", vum->gso_count);
+  for (u32 tid = 0; tid <= vlib_num_workers (); tid++)
+    {
+      vhost_cpu_t *cpu = vec_elt_at_index (vum->cpus, tid);
+      vlib_cli_output (vm, "  Thread %u: Polling queue count %u", tid,
+		       cpu->polling_q_count);
+    }
+
+  for (i = 0; i < vec_len (hw_if_indices); i++)
+    {
+      hi = vnet_get_hw_interface (vnm, hw_if_indices[i]);
+      vui = pool_elt_at_index (vum->vhost_user_interfaces, hi->dev_instance);
+      vlib_cli_output (vm, "Interface: %U (ifindex %d)",
+		       format_vnet_hw_if_index_name, vnm, hw_if_indices[i],
+		       hw_if_indices[i]);
+      vlib_cli_output (vm, "  Number of qids %u", vui->num_qid);
+      if (vui->enable_gso)
+	vlib_cli_output (vm, "  GSO enable");
+      if (vui->enable_packed)
+	vlib_cli_output (vm, "  Packed ring enable");
+      if (vui->enable_event_idx)
+	vlib_cli_output (vm, "  Event index enable");
+
+      vlib_cli_output (vm, "virtio_net_hdr_sz %d\n"
+		       " features mask (0x%llx): \n"
+		       " features (0x%llx): \n",
+		       vui->virtio_net_hdr_sz, vui->feature_mask,
+		       vui->features);
+
+      feat_entry = (struct feat_struct *) &feat_array;
+      while (feat_entry->str)
+	{
+	  if (vui->features & (1ULL << feat_entry->bit))
+	    vlib_cli_output (vm, "   %s (%d)", feat_entry->str,
+			     feat_entry->bit);
+	  feat_entry++;
+	}
+
+      vlib_cli_output (vm, "  protocol features (0x%llx)",
+		       vui->protocol_features);
+      feat_entry = (struct feat_struct *) &proto_feat_array;
+      while (feat_entry->str)
+	{
+	  if (vui->protocol_features & (1ULL << feat_entry->bit))
+	    vlib_cli_output (vm, "   %s (%d)", feat_entry->str,
+			     feat_entry->bit);
+	  feat_entry++;
+	}
+
+      vlib_cli_output (vm, "\n");
+
+      vlib_cli_output (vm, " socket filename %s type %s errno \"%s\"\n\n",
+		       vui->sock_filename,
+		       (vui->unix_server_index != ~0) ? "server" : "client",
+		       strerror (vui->sock_errno));
+
+      vlib_cli_output (vm, " rx placement: ");
+
+      FOR_ALL_VHOST_TXQ (qid, vui)
+      {
+	vhost_user_vring_t *txvq = &vui->vrings[qid];
+
+	if (txvq->qid == -1)
+	  continue;
+	vlib_cli_output (vm, "   thread %d on vring %d, %U\n",
+			 txvq->thread_index, qid, format_vnet_hw_if_rx_mode,
+			 txvq->mode);
+      }
+
+      vlib_cli_output (vm, " tx placement\n");
+
+      FOR_ALL_VHOST_RXQ (qid, vui)
+      {
+	vhost_user_vring_t *rxvq = &vui->vrings[qid];
+	vnet_hw_if_tx_queue_t *txq;
+
+	if (rxvq->queue_index == ~0)
+	  continue;
+	txq = vnet_hw_if_get_tx_queue (vnm, rxvq->queue_index);
+	if (txq->threads)
+	  vlib_cli_output (vm, "   threads %U on vring %u: %s\n",
+			   format_bitmap_list, txq->threads, qid,
+			   txq->shared_queue ? "spin-lock" : "lock-free");
+      }
+
+      vlib_cli_output (vm, "\n");
+
+      vlib_cli_output (vm, " Memory regions (total %d)\n", vui->nregions);
+
+      if (vui->nregions)
+	{
+	  vlib_cli_output (vm,
+			   " region fd    guest_phys_addr    memory_size        userspace_addr     mmap_offset        mmap_addr\n");
+	  vlib_cli_output (vm,
+			   " ====== ===== ================== ================== ================== ================== ==================\n");
+	}
+      for (j = 0; j < vui->nregions; j++)
+	{
+	  vlib_cli_output (vm,
+			   "  %d     %-5d 0x%016lx 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n",
+			   j, vui->region_mmap_fd[j],
+			   vui->regions[j].guest_phys_addr,
+			   vui->regions[j].memory_size,
+			   vui->regions[j].userspace_addr,
+			   vui->regions[j].mmap_offset,
+			   pointer_to_uword (vui->region_mmap_addr[j]));
+	}
+      FOR_ALL_VHOST_RX_TXQ (q, vui)
+      {
+	if (!vui->vrings[q].started)
+	  continue;
+
+	vlib_cli_output (vm, "\n Virtqueue %d (%s%s)\n", q,
+			 (q & 1) ? "RX" : "TX",
+			 vui->vrings[q].enabled ? "" : " disabled");
+	vlib_cli_output (vm, "  global %s queue index %u\n",
+			 (q & 1) ? "RX" : "TX", vui->vrings[q].queue_index);
+
+	vlib_cli_output (
+	  vm,
+	  "  qsz %d last_avail_idx %d last_used_idx %d"
+	  " last_kick %u\n",
+	  vui->vrings[q].qsz_mask + 1, vui->vrings[q].last_avail_idx,
+	  vui->vrings[q].last_used_idx, vui->vrings[q].last_kick);
+
+	if (vhost_user_is_packed_ring_supported (vui))
+	  vhost_user_show_desc_packed (vm, vui, q, show_descr, show_verbose);
+	else
+	  vhost_user_show_desc (vm, vui, q, show_descr, show_verbose);
+      }
+      vlib_cli_output (vm, "\n");
+    }
+done:
+  vec_free (hw_if_indices);
+  return error;
+}
+
+/*
+ * CLI functions
+ */
+
+/*?
+ * Create a vHost User interface. Once created, a new virtual interface
+ * will exist with the name '<em>VirtualEthernet0/0/x</em>', where '<em>x</em>'
+ * is the next free index.
+ *
+ * There are several parameters associated with a vHost interface:
+ *
+ * - <b>socket <socket-filename></b> - Name of the linux socket used by
+ * hypervisor and VPP to manage the vHost interface. If in <em>server</em>
+ * mode, VPP will create the socket if it does not already exist. If in
+ * <em>client</em> mode, hypervisor will create the socket if it does not
+ * already exist. The VPP code is indifferent to the file location. However,
+ * if SELinux is enabled, then the socket needs to be created in
+ * <em>/var/run/vpp/</em>.
+ *
+ * - <b>server</b> - Optional flag to indicate that VPP should be the server
+ * for the linux socket. If not provided, VPP will be the client. In
+ * <em>server</em> mode, the VM can be reset without tearing down the vHost
+ * Interface. In <em>client</em> mode, VPP can be reset without bringing down
+ * the VM and tearing down the vHost Interface.
+ *
+ * - <b>feature-mask <hex></b> - Optional virtio/vhost feature set negotiated
+ * at startup. <b>This is intended for degugging only.</b> It is recommended
+ * that this parameter not be used except by experienced users. By default,
+ * all supported features will be advertised. Otherwise, provide the set of
+ * features desired.
+ *   - 0x000008000 (15) - VIRTIO_NET_F_MRG_RXBUF
+ *   - 0x000020000 (17) - VIRTIO_NET_F_CTRL_VQ
+ *   - 0x000200000 (21) - VIRTIO_NET_F_GUEST_ANNOUNCE
+ *   - 0x000400000 (22) - VIRTIO_NET_F_MQ
+ *   - 0x004000000 (26) - VHOST_F_LOG_ALL
+ *   - 0x008000000 (27) - VIRTIO_F_ANY_LAYOUT
+ *   - 0x010000000 (28) - VIRTIO_F_INDIRECT_DESC
+ *   - 0x040000000 (30) - VHOST_USER_F_PROTOCOL_FEATURES
+ *   - 0x100000000 (32) - VIRTIO_F_VERSION_1
+ *
+ * - <b>hwaddr <mac-addr></b> - Optional ethernet address, can be in either
+ * X:X:X:X:X:X unix or X.X.X cisco format.
+ *
+ * - <b>renumber <dev_instance></b> - Optional parameter which allows the
+ * instance in the name to be specified. If instance already exists, name
+ * will be used anyway and multiple instances will have the same name. Use
+ * with caution.
+ *
+ * @cliexpar
+ * Example of how to create a vhost interface with VPP as the client and all
+ * features enabled:
+ * @cliexstart{create vhost-user socket /var/run/vpp/vhost1.sock}
+ * VirtualEthernet0/0/0
+ * @cliexend
+ * Example of how to create a vhost interface with VPP as the server and with
+ * just multiple queues enabled:
+ * @cliexstart{create vhost-user socket /var/run/vpp/vhost2.sock server
+ * feature-mask 0x40400000}
+ * VirtualEthernet0/0/1
+ * @cliexend
+ * Once the vHost interface is created, enable the interface using:
+ * @cliexcmd{set interface state VirtualEthernet0/0/0 up}
+?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (vhost_user_connect_command, static) = {
+    .path = "create vhost-user",
+    .short_help = "create vhost-user socket <socket-filename> [server] "
+    "[feature-mask <hex>] [hwaddr <mac-addr>] [renumber <dev_instance>] [gso] "
+    "[packed] [event-idx]",
+    .function = vhost_user_connect_command_fn,
+    .is_mp_safe = 1,
+};
+/* *INDENT-ON* */
+
+/*?
+ * Delete a vHost User interface using the interface name or the
+ * software interface index. Use the '<em>show interface</em>'
+ * command to determine the software interface index. On deletion,
+ * the linux socket will not be deleted.
+ *
+ * @cliexpar
+ * Example of how to delete a vhost interface by name:
+ * @cliexcmd{delete vhost-user VirtualEthernet0/0/1}
+ * Example of how to delete a vhost interface by software interface index:
+ * @cliexcmd{delete vhost-user sw_if_index 1}
+?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (vhost_user_delete_command, static) = {
+    .path = "delete vhost-user",
+    .short_help = "delete vhost-user {<interface> | sw_if_index <sw_idx>}",
+    .function = vhost_user_delete_command_fn,
+};
+
+/*?
+ * Display the attributes of a single vHost User interface (provide interface
+ * name), multiple vHost User interfaces (provide a list of interface names
+ * separated by spaces) or all Vhost User interfaces (omit an interface name
+ * to display all vHost interfaces).
+ *
+ * @cliexpar
+ * @parblock
+ * Example of how to display a vhost interface:
+ * @cliexstart{show vhost-user VirtualEthernet0/0/0}
+ * Virtio vhost-user interfaces
+ * Global:
+ *   coalesce frames 32 time 1e-3
+ * Interface: VirtualEthernet0/0/0 (ifindex 1)
+ * virtio_net_hdr_sz 12
+ *  features mask (0xffffffffffffffff):
+ *  features (0x50408000):
+ *    VIRTIO_NET_F_MRG_RXBUF (15)
+ *    VIRTIO_NET_F_MQ (22)
+ *    VIRTIO_F_INDIRECT_DESC (28)
+ *    VHOST_USER_F_PROTOCOL_FEATURES (30)
+ *   protocol features (0x3)
+ *    VHOST_USER_PROTOCOL_F_MQ (0)
+ *    VHOST_USER_PROTOCOL_F_LOG_SHMFD (1)
+ *
+ *  socket filename /var/run/vpp/vhost1.sock type client errno "Success"
+ *
+ * rx placement:
+ *    thread 1 on vring 1
+ *    thread 1 on vring 5
+ *    thread 2 on vring 3
+ *    thread 2 on vring 7
+ *  tx placement: spin-lock
+ *    thread 0 on vring 0
+ *    thread 1 on vring 2
+ *    thread 2 on vring 0
+ *
+ * Memory regions (total 2)
+ * region fd guest_phys_addr memory_size userspace_addr mmap_offset mmap_addr
+ * ====== == =============== =========== ============== =========== ==========
+ *   0    60  0x00000000     0x000a0000  0xaac00000     0x00000000  0x2b400000
+ *   1    61  0x000c0000     0x3ff40000  0xaacc0000     0x000c0000  0xabcc0000
+ *
+ *  Virtqueue 0 (TX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 128 used.flags 1 used.idx 0
+ *   kickfd 62 callfd 64 errfd -1
+ *
+ *  Virtqueue 1 (RX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 65 callfd 66 errfd -1
+ *
+ *  Virtqueue 2 (TX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 128 used.flags 1 used.idx 0
+ *   kickfd 63 callfd 70 errfd -1
+ *
+ *  Virtqueue 3 (RX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 72 callfd 74 errfd -1
+ *
+ *  Virtqueue 4 (TX disabled)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 76 callfd 78 errfd -1
+ *
+ *  Virtqueue 5 (RX disabled)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 80 callfd 82 errfd -1
+ *
+ *  Virtqueue 6 (TX disabled)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *  avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 84 callfd 86 errfd -1
+ *
+ *  Virtqueue 7 (RX disabled)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 0 used.flags 1 used.idx 0
+ *   kickfd 88 callfd 90 errfd -1
+ *
+ * @cliexend
+ *
+ * The optional '<em>descriptors</em>' parameter will display the same output
+ * as the previous example but will include the descriptor table for each
+ * queue.
+ * The output is truncated below:
+ * @cliexstart{show vhost-user VirtualEthernet0/0/0 descriptors}
+ * Virtio vhost-user interfaces
+ * Global:
+ *   coalesce frames 32 time 1e-3
+ * Interface: VirtualEthernet0/0/0 (ifindex 1)
+ * virtio_net_hdr_sz 12
+ *  features mask (0xffffffffffffffff):
+ *  features (0x50408000):
+ *    VIRTIO_NET_F_MRG_RXBUF (15)
+ *    VIRTIO_NET_F_MQ (22)
+ * :
+ *  Virtqueue 0 (TX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ *   avail.flags 1 avail.idx 128 used.flags 1 used.idx 0
+ *   kickfd 62 callfd 64 errfd -1
+ *
+ *   descriptor table:
+ *    id          addr         len  flags  next      user_addr
+ *   ===== ================== ===== ====== ===== ==================
+ *   0     0x0000000010b6e974 2060  0x0002 1     0x00002aabbc76e974
+ *   1     0x0000000010b6e034 2060  0x0002 2     0x00002aabbc76e034
+ *   2     0x0000000010b6d6f4 2060  0x0002 3     0x00002aabbc76d6f4
+ *   3     0x0000000010b6cdb4 2060  0x0002 4     0x00002aabbc76cdb4
+ *   4     0x0000000010b6c474 2060  0x0002 5     0x00002aabbc76c474
+ *   5     0x0000000010b6bb34 2060  0x0002 6     0x00002aabbc76bb34
+ *   6     0x0000000010b6b1f4 2060  0x0002 7     0x00002aabbc76b1f4
+ *   7     0x0000000010b6a8b4 2060  0x0002 8     0x00002aabbc76a8b4
+ *   8     0x0000000010b69f74 2060  0x0002 9     0x00002aabbc769f74
+ *   9     0x0000000010b69634 2060  0x0002 10    0x00002aabbc769634
+ *   10    0x0000000010b68cf4 2060  0x0002 11    0x00002aabbc768cf4
+ * :
+ *   249   0x0000000000000000 0     0x0000 250   0x00002aab2b400000
+ *   250   0x0000000000000000 0     0x0000 251   0x00002aab2b400000
+ *   251   0x0000000000000000 0     0x0000 252   0x00002aab2b400000
+ *   252   0x0000000000000000 0     0x0000 253   0x00002aab2b400000
+ *   253   0x0000000000000000 0     0x0000 254   0x00002aab2b400000
+ *   254   0x0000000000000000 0     0x0000 255   0x00002aab2b400000
+ *   255   0x0000000000000000 0     0x0000 32768 0x00002aab2b400000
+ *
+ *  Virtqueue 1 (RX)
+ *   qsz 256 last_avail_idx 0 last_used_idx 0
+ * :
+ * @cliexend
+ * @endparblock
+?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (show_vhost_user_command, static) = {
+    .path = "show vhost-user",
+    .short_help = "show vhost-user [<interface> [<interface> [..]]] "
+    "[[descriptors] [verbose]]",
+    .function = show_vhost_user_command_fn,
+};
+/* *INDENT-ON* */
+
+
+static clib_error_t *
+vhost_user_config (vlib_main_t * vm, unformat_input_t * input)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "coalesce-frames %d", &vum->coalesce_frames))
+	;
+      else if (unformat (input, "coalesce-time %f", &vum->coalesce_time))
+	;
+      else if (unformat (input, "dont-dump-memory"))
+	vum->dont_dump_vhost_user_memory = 1;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+
+  return 0;
+}
+
+/* vhost-user { ... } configuration. */
+VLIB_CONFIG_FUNCTION (vhost_user_config, "vhost-user");
+
+void
+vhost_user_unmap_all (void)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+
+  if (vum->dont_dump_vhost_user_memory)
+    {
+      pool_foreach (vui, vum->vhost_user_interfaces)
+	unmap_all_mem_regions (vui);
+    }
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user.h b/src/plugins/vhost/vhost_user.h
new file mode 100644
index 00000000000..3479d65cbc6
--- /dev/null
+++ b/src/plugins/vhost/vhost_user.h
@@ -0,0 +1,388 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __VIRTIO_VHOST_USER_H__
+#define __VIRTIO_VHOST_USER_H__
+
+#include <vhost/virtio_std.h>
+#include <vhost/vhost_std.h>
+
+/* vhost-user data structures */
+
+#define VHOST_MEMORY_MAX_NREGIONS       8
+#define VHOST_USER_MSG_HDR_SZ           12
+#define VHOST_VRING_INIT_MQ_PAIR_SZ     8	//8TX + 8RX
+
+/*
+ * qid is one byte in size in the spec. Please see VHOST_USER_SET_VRING_CALL,
+ * VHOST_USER_SET_VRING_KICK, and VHOST_USER_SET_VRING_ERR.
+ * The max number for q pair is naturally 128.
+ */
+#define VHOST_VRING_MAX_MQ_PAIR_SZ      128
+#define VHOST_VRING_IDX_RX(qid)		(2 * (qid))
+#define VHOST_VRING_IDX_TX(qid)		(2 * (qid) + 1)
+
+#define VHOST_USER_VRING_NOFD_MASK      0x100
+
+#define VHOST_USER_PROTOCOL_F_MQ   0
+#define VHOST_USER_PROTOCOL_F_LOG_SHMFD	1
+#define VHOST_VRING_F_LOG 0
+
+#define VHOST_USER_PROTOCOL_FEATURES   ((1ULL << VHOST_USER_PROTOCOL_F_MQ) |	\
+					(1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD))
+
+#define vu_log_debug(dev, f, ...) \
+{                                                                             \
+  vlib_log(VLIB_LOG_LEVEL_DEBUG, vhost_user_main.log_default, "%U: " f,       \
+	   format_vnet_hw_if_index_name, vnet_get_main(),                     \
+	   dev->hw_if_index, ##__VA_ARGS__);                                  \
+};
+
+#define vu_log_warn(dev, f, ...) \
+{                                                                             \
+  vlib_log(VLIB_LOG_LEVEL_WARNING, vhost_user_main.log_default, "%U: " f,     \
+	   format_vnet_hw_if_index_name, vnet_get_main(),                     \
+	   dev->hw_if_index, ##__VA_ARGS__);                                  \
+};
+#define vu_log_err(dev, f, ...) \
+{                                                                             \
+  vlib_log(VLIB_LOG_LEVEL_ERR, vhost_user_main.log_default, "%U: " f,         \
+	   format_vnet_hw_if_index_name, vnet_get_main(),                     \
+	   dev->hw_if_index, ##__VA_ARGS__);                                  \
+};
+
+#define UNIX_GET_FD(unixfd_idx) ({ \
+    typeof(unixfd_idx) __unixfd_idx = (unixfd_idx); \
+    (__unixfd_idx != ~0) ? \
+        pool_elt_at_index (file_main.file_pool, \
+                           __unixfd_idx)->file_descriptor : -1; })
+
+#define foreach_virtio_trace_flags \
+  _ (SIMPLE_CHAINED, 0, "Simple descriptor chaining") \
+  _ (SINGLE_DESC,  1, "Single descriptor packet") \
+  _ (INDIRECT, 2, "Indirect descriptor") \
+  _ (MAP_ERROR, 4, "Memory mapping error")
+
+typedef enum
+{
+#define _(n,i,s) VIRTIO_TRACE_F_##n,
+  foreach_virtio_trace_flags
+#undef _
+} virtio_trace_flag_t;
+
+#define FEATURE_VIRTIO_NET_F_HOST_TSO_FEATURE_BITS \
+  (VIRTIO_FEATURE (VIRTIO_NET_F_CSUM) |		   \
+   VIRTIO_FEATURE (VIRTIO_NET_F_HOST_UFO) |	   \
+   VIRTIO_FEATURE (VIRTIO_NET_F_HOST_TSO4) |	   \
+   VIRTIO_FEATURE (VIRTIO_NET_F_HOST_TSO6))
+
+#define FEATURE_VIRTIO_NET_F_GUEST_TSO_FEATURE_BITS \
+  (VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_CSUM) |	    \
+   VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_UFO) |	    \
+   VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_TSO4) |	    \
+   VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_TSO6))
+
+#define FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS \
+  (FEATURE_VIRTIO_NET_F_HOST_TSO_FEATURE_BITS |		 \
+   FEATURE_VIRTIO_NET_F_GUEST_TSO_FEATURE_BITS)
+
+
+typedef struct
+{
+  char *sock_filename;
+  u64 feature_mask;
+  u32 custom_dev_instance;
+  u8 hwaddr[6];
+  u8 renumber;
+  u8 is_server;
+  u8 enable_gso;
+  u8 enable_packed;
+  u8 enable_event_idx;
+  u8 use_custom_mac;
+
+  /* return */
+  u32 sw_if_index;
+} vhost_user_create_if_args_t;
+
+int vhost_user_create_if (vnet_main_t * vnm, vlib_main_t * vm,
+			  vhost_user_create_if_args_t * args);
+int vhost_user_modify_if (vnet_main_t * vnm, vlib_main_t * vm,
+			  vhost_user_create_if_args_t * args);
+int vhost_user_delete_if (vnet_main_t * vnm, vlib_main_t * vm,
+			  u32 sw_if_index);
+
+/* *INDENT-OFF* */
+typedef struct vhost_user_memory_region
+{
+  u64 guest_phys_addr;
+  u64 memory_size;
+  u64 userspace_addr;
+  u64 mmap_offset;
+} __attribute ((packed)) vhost_user_memory_region_t;
+
+typedef struct vhost_user_memory
+{
+  u32 nregions;
+  u32 padding;
+  vhost_user_memory_region_t regions[VHOST_MEMORY_MAX_NREGIONS];
+} __attribute ((packed)) vhost_user_memory_t;
+
+typedef enum vhost_user_req
+{
+  VHOST_USER_NONE = 0,
+  VHOST_USER_GET_FEATURES = 1,
+  VHOST_USER_SET_FEATURES = 2,
+  VHOST_USER_SET_OWNER = 3,
+  VHOST_USER_RESET_OWNER = 4,
+  VHOST_USER_SET_MEM_TABLE = 5,
+  VHOST_USER_SET_LOG_BASE = 6,
+  VHOST_USER_SET_LOG_FD = 7,
+  VHOST_USER_SET_VRING_NUM = 8,
+  VHOST_USER_SET_VRING_ADDR = 9,
+  VHOST_USER_SET_VRING_BASE = 10,
+  VHOST_USER_GET_VRING_BASE = 11,
+  VHOST_USER_SET_VRING_KICK = 12,
+  VHOST_USER_SET_VRING_CALL = 13,
+  VHOST_USER_SET_VRING_ERR = 14,
+  VHOST_USER_GET_PROTOCOL_FEATURES = 15,
+  VHOST_USER_SET_PROTOCOL_FEATURES = 16,
+  VHOST_USER_GET_QUEUE_NUM = 17,
+  VHOST_USER_SET_VRING_ENABLE = 18,
+  VHOST_USER_MAX
+} vhost_user_req_t;
+
+typedef struct vhost_user_msg {
+  vhost_user_req_t request;
+  u32 flags;
+  u32 size;
+  union
+    {
+      u64 u64;
+      vhost_vring_state_t state;
+      vhost_vring_addr_t addr;
+      vhost_user_memory_t memory;
+      vhost_user_log_t log;
+    };
+} __attribute ((packed)) vhost_user_msg_t;
+/* *INDENT-ON* */
+
+typedef struct
+{
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+  u16 qsz_mask;
+  u16 last_avail_idx;
+  u16 last_used_idx;
+  u16 n_since_last_int;
+  union
+  {
+    vnet_virtio_vring_desc_t *desc;
+    vnet_virtio_vring_packed_desc_t *packed_desc;
+  };
+  union
+  {
+    vnet_virtio_vring_avail_t *avail;
+    vnet_virtio_vring_desc_event_t *avail_event;
+  };
+  union
+  {
+    vnet_virtio_vring_used_t *used;
+    vnet_virtio_vring_desc_event_t *used_event;
+  };
+  uword desc_user_addr;
+  uword used_user_addr;
+  uword avail_user_addr;
+  f64 int_deadline;
+  u8 started;
+  u8 enabled;
+  u8 log_used;
+  clib_spinlock_t vring_lock;
+
+  //Put non-runtime in a different cache line
+    CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);
+  int errfd;
+  u32 callfd_idx;
+  u32 kickfd_idx;
+  u64 log_guest_addr;
+
+  /* The rx queue policy (interrupt/adaptive/polling) for this queue */
+  u32 mode;
+
+  /*
+   * It contains the device queue number. -1 if it does not. The idea is
+   * to not invoke vnet_hw_interface_assign_rx_thread and
+   * vnet_hw_interface_unassign_rx_thread more than once for the duration of
+   * the interface even if it is disconnected and reconnected.
+   */
+  i16 qid;
+
+  u16 used_wrap_counter;
+  u16 avail_wrap_counter;
+  u16 last_kick;
+  u8 first_kick;
+  u32 queue_index;
+  u32 thread_index;
+} vhost_user_vring_t;
+
+#define VHOST_USER_EVENT_START_TIMER 1
+#define VHOST_USER_EVENT_STOP_TIMER  2
+
+typedef struct
+{
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+  u32 is_ready;
+  u32 admin_up;
+  u32 unix_server_index;
+  u32 clib_file_index;
+  char sock_filename[256];
+  int sock_errno;
+  uword if_index;
+  u32 hw_if_index, sw_if_index;
+
+  //Feature negotiation
+  u64 features;
+  u64 feature_mask;
+  u64 protocol_features;
+
+  //Memory region information
+  u32 nregions;
+  vhost_user_memory_region_t regions[VHOST_MEMORY_MAX_NREGIONS];
+  void *region_mmap_addr[VHOST_MEMORY_MAX_NREGIONS];
+  u64 region_guest_addr_lo[VHOST_MEMORY_MAX_NREGIONS];
+  u64 region_guest_addr_hi[VHOST_MEMORY_MAX_NREGIONS];
+  u32 region_mmap_fd[VHOST_MEMORY_MAX_NREGIONS];
+
+  //Virtual rings
+  vhost_user_vring_t *vrings;
+
+  /*
+   * vrings is a dynamic array. It may have more elements than it is
+   * currently used. num_qid indicates the current total qid's in the
+   * vrings. For example, vec_len(vrings) = 64, num_qid = 60, so the
+   * current valid/used qid is (0, 59) in the vrings array.
+   */
+  u32 num_qid;
+
+  int virtio_net_hdr_sz;
+  int is_any_layout;
+
+  void *log_base_addr;
+  u64 log_size;
+
+  u8 enable_gso;
+
+  /* Packed ring configured */
+  u8 enable_packed;
+
+  u8 enable_event_idx;
+} vhost_user_intf_t;
+
+#define FOR_ALL_VHOST_TXQ(qid, vui) for (qid = 1; qid < vui->num_qid; qid += 2)
+
+#define FOR_ALL_VHOST_RXQ(qid, vui) for (qid = 0; qid < vui->num_qid; qid += 2)
+
+#define FOR_ALL_VHOST_RX_TXQ(qid, vui) for (qid = 0; qid < vui->num_qid; qid++)
+
+typedef struct
+{
+  uword dst;
+  uword src;
+  u32 len;
+} vhost_copy_t;
+
+typedef struct
+{
+  u16 qid; /** The interface queue index (Not the virtio vring idx) */
+  u16 device_index; /** The device index */
+  u32 virtio_ring_flags; /** Runtime queue flags  **/
+  u16 first_desc_len; /** Length of the first data descriptor **/
+  vnet_virtio_net_hdr_mrg_rxbuf_t hdr; /** Virtio header **/
+} vhost_trace_t;
+
+#define VHOST_USER_RX_BUFFERS_N (2 * VLIB_FRAME_SIZE + 2)
+#define VHOST_USER_COPY_ARRAY_N (4 * VLIB_FRAME_SIZE)
+
+typedef struct
+{
+  u32 rx_buffers_len;
+  u32 rx_buffers[VHOST_USER_RX_BUFFERS_N];
+
+  vnet_virtio_net_hdr_mrg_rxbuf_t tx_headers[VLIB_FRAME_SIZE];
+  vhost_copy_t copy[VHOST_USER_COPY_ARRAY_N];
+
+  /* This is here so it doesn't end-up
+   * using stack or registers. */
+  vhost_trace_t *current_trace;
+
+  u32 *to_next_list;
+  vlib_buffer_t **rx_buffers_pdesc;
+  u32 polling_q_count;
+} vhost_cpu_t;
+
+typedef struct
+{
+  mhash_t if_index_by_sock_name;
+  u32 mtu_bytes;
+  vhost_user_intf_t *vhost_user_interfaces;
+  u32 *show_dev_instance_by_real_dev_instance;
+  u32 coalesce_frames;
+  f64 coalesce_time;
+  int dont_dump_vhost_user_memory;
+
+  /** Per-CPU data for vhost-user */
+  vhost_cpu_t *cpus;
+
+  /** Pseudo random iterator */
+  u32 random;
+
+  /* The number of rx interface/queue pairs in interrupt mode */
+  u32 ifq_count;
+
+  /* logging */
+  vlib_log_class_t log_default;
+
+  /* gso interface count */
+  u32 gso_count;
+} vhost_user_main_t;
+
+typedef struct
+{
+  u8 if_name[64];
+  u32 sw_if_index;
+  u32 virtio_net_hdr_sz;
+  u64 features;
+  u8 is_server;
+  u8 sock_filename[256];
+  u32 num_regions;
+  int sock_errno;
+} vhost_user_intf_details_t;
+
+int vhost_user_dump_ifs (vnet_main_t * vnm, vlib_main_t * vm,
+			 vhost_user_intf_details_t ** out_vuids);
+void vhost_user_set_operation_mode (vhost_user_intf_t *vui,
+				    vhost_user_vring_t *txvq);
+
+extern vlib_node_registration_t vhost_user_send_interrupt_node;
+extern vnet_device_class_t vhost_user_device_class;
+extern vlib_node_registration_t vhost_user_input_node;
+extern vhost_user_main_t vhost_user_main;
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user_api.c b/src/plugins/vhost/vhost_user_api.c
new file mode 100644
index 00000000000..d522803a011
--- /dev/null
+++ b/src/plugins/vhost/vhost_user_api.c
@@ -0,0 +1,358 @@
+/*
+ *------------------------------------------------------------------
+ * vhost-user_api.c - vhost-user api
+ *
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#include <vnet/vnet.h>
+#include <vlibmemory/api.h>
+
+#include <vnet/interface.h>
+#include <vnet/api_errno.h>
+#include <vhost/vhost_user.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ethernet/ethernet_types_api.h>
+
+#include <vnet/format_fns.h>
+#include <vhost/vhost_user.api_enum.h>
+#include <vhost/vhost_user.api_types.h>
+
+#define REPLY_MSG_ID_BASE msg_id_base
+#include <vlibapi/api_helper_macros.h>
+
+static u16 msg_id_base;
+
+static void
+vl_api_create_vhost_user_if_t_handler (vl_api_create_vhost_user_if_t * mp)
+{
+  int rv = 0;
+  vl_api_create_vhost_user_if_reply_t *rmp;
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+  u64 disabled_features = (u64) (0ULL);
+  vhost_user_create_if_args_t args = { 0 };
+
+  args.sw_if_index = (u32) ~ 0;
+  args.feature_mask = (u64) ~ (0ULL);
+  if (mp->disable_mrg_rxbuf)
+    disabled_features = VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF);
+
+  if (mp->disable_indirect_desc)
+    disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_INDIRECT_DESC);
+
+  /*
+   * GSO and PACKED are not supported by feature mask via binary API. We
+   * disable GSO and PACKED feature in the feature mask. They may be enabled
+   * explicitly via enable_gso and enable_packed argument
+   */
+  disabled_features |= FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS |
+    VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+
+  /* EVENT_IDX is disabled by default */
+  disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+  args.feature_mask &= ~disabled_features;
+
+  if (mp->use_custom_mac)
+    mac_address_decode (mp->mac_address, (mac_address_t *) args.hwaddr);
+
+  args.use_custom_mac = mp->use_custom_mac;
+  args.is_server = mp->is_server;
+  args.sock_filename = (char *) mp->sock_filename;
+  args.renumber = mp->renumber;
+  args.custom_dev_instance = ntohl (mp->custom_dev_instance);
+  args.enable_gso = mp->enable_gso;
+  args.enable_packed = mp->enable_packed;
+  rv = vhost_user_create_if (vnm, vm, &args);
+
+  /* Remember an interface tag for the new interface */
+  if (rv == 0)
+    {
+      /* If a tag was supplied... */
+      if (mp->tag[0])
+	{
+	  /* Make sure it's a proper C-string */
+	  mp->tag[ARRAY_LEN (mp->tag) - 1] = 0;
+	  u8 *tag = format (0, "%s%c", mp->tag, 0);
+	  vnet_set_sw_interface_tag (vnm, tag, args.sw_if_index);
+	}
+    }
+
+  /* *INDENT-OFF* */
+  REPLY_MACRO2(VL_API_CREATE_VHOST_USER_IF_REPLY,
+  ({
+    rmp->sw_if_index = ntohl (args.sw_if_index);
+  }));
+  /* *INDENT-ON* */
+}
+
+static void
+vl_api_modify_vhost_user_if_t_handler (vl_api_modify_vhost_user_if_t * mp)
+{
+  int rv = 0;
+  vl_api_modify_vhost_user_if_reply_t *rmp;
+  u64 disabled_features = (u64) (0ULL);
+  vhost_user_create_if_args_t args = { 0 };
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  args.feature_mask = (u64) ~ (0ULL);
+  /*
+   * GSO and PACKED are not supported by feature mask via binary API. We
+   * disable GSO and PACKED feature in the feature mask. They may be enabled
+   * explicitly via enable_gso and enable_packed argument
+   */
+  disabled_features |= FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS |
+    VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+
+  /* EVENT_IDX is disabled by default */
+  disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+  args.feature_mask &= ~disabled_features;
+
+  args.sw_if_index = ntohl (mp->sw_if_index);
+  args.sock_filename = (char *) mp->sock_filename;
+  args.is_server = mp->is_server;
+  args.renumber = mp->renumber;
+  args.custom_dev_instance = ntohl (mp->custom_dev_instance);
+  args.enable_gso = mp->enable_gso;
+  args.enable_packed = mp->enable_packed;
+  rv = vhost_user_modify_if (vnm, vm, &args);
+
+  REPLY_MACRO (VL_API_MODIFY_VHOST_USER_IF_REPLY);
+}
+
+static void
+vl_api_create_vhost_user_if_v2_t_handler (vl_api_create_vhost_user_if_v2_t *
+					  mp)
+{
+  int rv = 0;
+  vl_api_create_vhost_user_if_v2_reply_t *rmp;
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+  u64 disabled_features = (u64) (0ULL);
+  vhost_user_create_if_args_t args = { 0 };
+
+  args.sw_if_index = (u32) ~ 0;
+  args.feature_mask = (u64) ~ (0ULL);
+  if (mp->disable_mrg_rxbuf)
+    disabled_features = VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF);
+
+  if (mp->disable_indirect_desc)
+    disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_INDIRECT_DESC);
+
+  /*
+   * GSO and PACKED are not supported by feature mask via binary API. We
+   * disable GSO and PACKED feature in the feature mask. They may be enabled
+   * explicitly via enable_gso and enable_packed argument
+   */
+  disabled_features |= FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS |
+    VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+
+  /* EVENT_IDX is disabled by default */
+  disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+  args.feature_mask &= ~disabled_features;
+
+  if (mp->use_custom_mac)
+    mac_address_decode (mp->mac_address, (mac_address_t *) args.hwaddr);
+
+  args.use_custom_mac = mp->use_custom_mac;
+  args.is_server = mp->is_server;
+  args.sock_filename = (char *) mp->sock_filename;
+  args.renumber = mp->renumber;
+  args.custom_dev_instance = ntohl (mp->custom_dev_instance);
+  args.enable_gso = mp->enable_gso;
+  args.enable_packed = mp->enable_packed;
+  args.enable_event_idx = mp->enable_event_idx;
+  rv = vhost_user_create_if (vnm, vm, &args);
+
+  /* Remember an interface tag for the new interface */
+  if (rv == 0)
+    {
+      /* If a tag was supplied... */
+      if (mp->tag[0])
+	{
+	  /* Make sure it's a proper C-string */
+	  mp->tag[ARRAY_LEN (mp->tag) - 1] = 0;
+	  u8 *tag = format (0, "%s%c", mp->tag, 0);
+	  vnet_set_sw_interface_tag (vnm, tag, args.sw_if_index);
+	}
+    }
+
+  /* *INDENT-OFF* */
+  REPLY_MACRO2(VL_API_CREATE_VHOST_USER_IF_V2_REPLY,
+  ({
+    rmp->sw_if_index = ntohl (args.sw_if_index);
+  }));
+  /* *INDENT-ON* */
+}
+
+static void
+vl_api_modify_vhost_user_if_v2_t_handler (vl_api_modify_vhost_user_if_v2_t *
+					  mp)
+{
+  int rv = 0;
+  vl_api_modify_vhost_user_if_v2_reply_t *rmp;
+  u64 disabled_features = (u64) (0ULL);
+  vhost_user_create_if_args_t args = { 0 };
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  args.feature_mask = (u64) ~ (0ULL);
+  /*
+   * GSO and PACKED are not supported by feature mask via binary API. We
+   * disable GSO and PACKED feature in the feature mask. They may be enabled
+   * explicitly via enable_gso and enable_packed argument
+   */
+  disabled_features |= FEATURE_VIRTIO_NET_F_HOST_GUEST_TSO_FEATURE_BITS |
+    VIRTIO_FEATURE (VIRTIO_F_RING_PACKED);
+
+  /* EVENT_IDX is disabled by default */
+  disabled_features |= VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX);
+  args.feature_mask &= ~disabled_features;
+
+  args.sw_if_index = ntohl (mp->sw_if_index);
+  args.sock_filename = (char *) mp->sock_filename;
+  args.is_server = mp->is_server;
+  args.renumber = mp->renumber;
+  args.custom_dev_instance = ntohl (mp->custom_dev_instance);
+  args.enable_gso = mp->enable_gso;
+  args.enable_packed = mp->enable_packed;
+  args.enable_event_idx = mp->enable_event_idx;
+  rv = vhost_user_modify_if (vnm, vm, &args);
+
+  REPLY_MACRO (VL_API_MODIFY_VHOST_USER_IF_V2_REPLY);
+}
+
+static void
+vl_api_delete_vhost_user_if_t_handler (vl_api_delete_vhost_user_if_t * mp)
+{
+  int rv = 0;
+  vl_api_delete_vhost_user_if_reply_t *rmp;
+  u32 sw_if_index = ntohl (mp->sw_if_index);
+  vl_api_registration_t *reg;
+
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  rv = vhost_user_delete_if (vnm, vm, sw_if_index);
+
+  REPLY_MACRO (VL_API_DELETE_VHOST_USER_IF_REPLY);
+  if (!rv)
+    {
+      reg = vl_api_client_index_to_registration (mp->client_index);
+      if (!reg)
+	return;
+
+      vnet_clear_sw_interface_tag (vnm, sw_if_index);
+    }
+}
+
+static void
+vhost_user_features_encode (u64 features, u32 *first, u32 *last)
+{
+  *first = clib_net_to_host_u32 (features);
+  *last = clib_net_to_host_u32 (features >> 32);
+}
+
+static void
+send_sw_interface_vhost_user_details (vpe_api_main_t * am,
+				      vl_api_registration_t * reg,
+				      vhost_user_intf_details_t * vui,
+				      u32 context)
+{
+  vl_api_sw_interface_vhost_user_details_t *mp;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  clib_memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id =
+    ntohs (REPLY_MSG_ID_BASE + VL_API_SW_INTERFACE_VHOST_USER_DETAILS);
+  mp->sw_if_index = ntohl (vui->sw_if_index);
+  mp->virtio_net_hdr_sz = ntohl (vui->virtio_net_hdr_sz);
+  vhost_user_features_encode (vui->features, (u32 *) &mp->features_first_32,
+			      (u32 *) &mp->features_last_32);
+  mp->is_server = vui->is_server;
+  mp->num_regions = ntohl (vui->num_regions);
+  mp->sock_errno = ntohl (vui->sock_errno);
+  mp->context = context;
+
+  strncpy ((char *) mp->sock_filename,
+	   (char *) vui->sock_filename, ARRAY_LEN (mp->sock_filename) - 1);
+  strncpy ((char *) mp->interface_name,
+	   (char *) vui->if_name, ARRAY_LEN (mp->interface_name) - 1);
+
+  vl_api_send_msg (reg, (u8 *) mp);
+}
+
+static void
+  vl_api_sw_interface_vhost_user_dump_t_handler
+  (vl_api_sw_interface_vhost_user_dump_t * mp)
+{
+  int rv = 0;
+  vpe_api_main_t *am = &vpe_api_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+  vhost_user_intf_details_t *ifaces = NULL;
+  vhost_user_intf_details_t *vuid = NULL;
+  vl_api_registration_t *reg;
+  u32 filter_sw_if_index;
+
+  reg = vl_api_client_index_to_registration (mp->client_index);
+  if (!reg)
+    return;
+
+  filter_sw_if_index = htonl (mp->sw_if_index);
+  if (filter_sw_if_index != ~0)
+    VALIDATE_SW_IF_INDEX (mp);
+
+  rv = vhost_user_dump_ifs (vnm, vm, &ifaces);
+  if (rv)
+    return;
+
+  vec_foreach (vuid, ifaces)
+  {
+    if ((filter_sw_if_index == ~0) ||
+	(vuid->sw_if_index == filter_sw_if_index))
+      send_sw_interface_vhost_user_details (am, reg, vuid, mp->context);
+  }
+  BAD_SW_IF_INDEX_LABEL;
+  vec_free (ifaces);
+}
+
+#include <vhost/vhost_user.api.c>
+static clib_error_t *
+vhost_user_api_hookup (vlib_main_t * vm)
+{
+  api_main_t *am = vlibapi_get_main ();
+  /* Mark CREATE_VHOST_USER_IF as mp safe */
+  vl_api_set_msg_thread_safe (am, VL_API_CREATE_VHOST_USER_IF, 1);
+  vl_api_set_msg_thread_safe (am, VL_API_CREATE_VHOST_USER_IF_V2, 1);
+
+  /*
+   * Set up the (msg_name, crc, message-id) table
+   */
+  REPLY_MSG_ID_BASE = setup_message_id_table ();
+
+  return 0;
+}
+
+VLIB_API_INIT_FUNCTION (vhost_user_api_hookup);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user_inline.h b/src/plugins/vhost/vhost_user_inline.h
new file mode 100644
index 00000000000..8bdff3733a7
--- /dev/null
+++ b/src/plugins/vhost/vhost_user_inline.h
@@ -0,0 +1,496 @@
+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __VIRTIO_VHOST_USER_INLINE_H__
+#define __VIRTIO_VHOST_USER_INLINE_H__
+/* vhost-user inline functions */
+#include <vppinfra/elog.h>
+
+static_always_inline void *
+map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
+{
+  int i = *hint;
+  if (PREDICT_TRUE ((vui->regions[i].guest_phys_addr <= addr) &&
+		    ((vui->regions[i].guest_phys_addr +
+		      vui->regions[i].memory_size) > addr)))
+    {
+      return (void *) (vui->region_mmap_addr[i] + addr -
+		       vui->regions[i].guest_phys_addr);
+    }
+#if __SSE4_2__
+  __m128i rl, rh, al, ah, r;
+  al = _mm_set1_epi64x (addr + 1);
+  ah = _mm_set1_epi64x (addr);
+
+  rl = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_lo[0]);
+  rl = _mm_cmpgt_epi64 (al, rl);
+  rh = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_hi[0]);
+  rh = _mm_cmpgt_epi64 (rh, ah);
+  r = _mm_and_si128 (rl, rh);
+
+  rl = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_lo[2]);
+  rl = _mm_cmpgt_epi64 (al, rl);
+  rh = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_hi[2]);
+  rh = _mm_cmpgt_epi64 (rh, ah);
+  r = _mm_blend_epi16 (r, _mm_and_si128 (rl, rh), 0x22);
+
+  rl = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_lo[4]);
+  rl = _mm_cmpgt_epi64 (al, rl);
+  rh = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_hi[4]);
+  rh = _mm_cmpgt_epi64 (rh, ah);
+  r = _mm_blend_epi16 (r, _mm_and_si128 (rl, rh), 0x44);
+
+  rl = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_lo[6]);
+  rl = _mm_cmpgt_epi64 (al, rl);
+  rh = _mm_loadu_si128 ((__m128i *) & vui->region_guest_addr_hi[6]);
+  rh = _mm_cmpgt_epi64 (rh, ah);
+  r = _mm_blend_epi16 (r, _mm_and_si128 (rl, rh), 0x88);
+
+  r = _mm_shuffle_epi8 (r, _mm_set_epi64x (0, 0x0e060c040a020800));
+  i = count_trailing_zeros (_mm_movemask_epi8 (r) |
+			    (1 << VHOST_MEMORY_MAX_NREGIONS));
+
+  if (i < vui->nregions)
+    {
+      *hint = i;
+      return (void *) (vui->region_mmap_addr[i] + addr -
+		       vui->regions[i].guest_phys_addr);
+    }
+#elif __aarch64__ && __ARM_NEON
+  uint64x2_t al, ah, rl, rh, r;
+  uint32_t u32 = 0;
+
+  al = vdupq_n_u64 (addr + 1);
+  ah = vdupq_n_u64 (addr);
+
+  /*First Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[0]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[0]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= (vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 1);
+
+  if (u32)
+    {
+      i = count_trailing_zeros (u32);
+      goto vhost_map_guest_mem_done;
+    }
+
+  /*Second Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[2]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[2]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 2);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 3);
+
+  if (u32)
+    {
+      i = count_trailing_zeros (u32);
+      goto vhost_map_guest_mem_done;
+    }
+
+  /*Third Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[4]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[4]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 6);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 7);
+
+  i = count_trailing_zeros (u32 | (1 << VHOST_MEMORY_MAX_NREGIONS));
+
+vhost_map_guest_mem_done:
+  if (i < vui->nregions)
+    {
+      *hint = i;
+      return (void *) (vui->region_mmap_addr[i] + addr -
+		       vui->regions[i].guest_phys_addr);
+    }
+#else
+  for (i = 0; i < vui->nregions; i++)
+    {
+      if ((vui->regions[i].guest_phys_addr <= addr) &&
+	  ((vui->regions[i].guest_phys_addr + vui->regions[i].memory_size) >
+	   addr))
+	{
+	  *hint = i;
+	  return (void *) (vui->region_mmap_addr[i] + addr -
+			   vui->regions[i].guest_phys_addr);
+	}
+    }
+#endif
+  /* *INDENT-OFF* */
+  ELOG_TYPE_DECLARE (el) =
+  {
+    .format = "failed to map guest mem addr %lx",
+    .format_args = "i8",
+  };
+  /* *INDENT-ON* */
+  struct
+  {
+    uword addr;
+  } *ed;
+  ed = ELOG_DATA (&vlib_global_main.elog_main, el);
+  ed->addr = addr;
+  *hint = 0;
+  return 0;
+}
+
+static_always_inline void *
+map_user_mem (vhost_user_intf_t * vui, uword addr)
+{
+  int i;
+  for (i = 0; i < vui->nregions; i++)
+    {
+      if ((vui->regions[i].userspace_addr <= addr) &&
+	  ((vui->regions[i].userspace_addr + vui->regions[i].memory_size) >
+	   addr))
+	{
+	  return (void *) (vui->region_mmap_addr[i] + addr -
+			   vui->regions[i].userspace_addr);
+	}
+    }
+  return 0;
+}
+
+#define VHOST_LOG_PAGE 0x1000
+
+static_always_inline void
+vhost_user_log_dirty_pages_2 (vhost_user_intf_t * vui,
+			      u64 addr, u64 len, u8 is_host_address)
+{
+  if (PREDICT_TRUE (vui->log_base_addr == 0
+		    || !(vui->features & VIRTIO_FEATURE (VHOST_F_LOG_ALL))))
+    {
+      return;
+    }
+  if (is_host_address)
+    {
+      addr = pointer_to_uword (map_user_mem (vui, (uword) addr));
+    }
+  if (PREDICT_FALSE ((addr + len - 1) / VHOST_LOG_PAGE / 8 >= vui->log_size))
+    {
+      vu_log_debug (vui, "vhost_user_log_dirty_pages(): out of range\n");
+      return;
+    }
+
+  CLIB_MEMORY_BARRIER ();
+  u64 page = addr / VHOST_LOG_PAGE;
+  while (page * VHOST_LOG_PAGE < addr + len)
+    {
+      ((u8 *) vui->log_base_addr)[page / 8] |= 1 << page % 8;
+      page++;
+    }
+}
+
+#define vhost_user_log_dirty_ring(vui, vq, member)                            \
+  if (PREDICT_FALSE (vq->log_used))                                           \
+    {                                                                         \
+      vhost_user_log_dirty_pages_2 (                                          \
+	vui,                                                                  \
+	vq->log_guest_addr +                                                  \
+	  STRUCT_OFFSET_OF (vnet_virtio_vring_used_t, member),                \
+	sizeof (vq->used->member), 0);                                        \
+    }
+
+static_always_inline u8 *
+format_vhost_trace (u8 * s, va_list * va)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
+  CLIB_UNUSED (vnet_main_t * vnm) = vnet_get_main ();
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_trace_t *t = va_arg (*va, vhost_trace_t *);
+  vhost_user_intf_t *vui = vum->vhost_user_interfaces + t->device_index;
+  vnet_sw_interface_t *sw;
+  u32 indent;
+
+  if (pool_is_free (vum->vhost_user_interfaces, vui))
+    {
+      s = format (s, "vhost-user interface is deleted");
+      return s;
+    }
+  sw = vnet_get_sw_interface (vnm, vui->sw_if_index);
+  indent = format_get_indent (s);
+  s = format (s, "%U %U queue %d\n", format_white_space, indent,
+	      format_vnet_sw_interface_name, vnm, sw, t->qid);
+
+  s = format (s, "%U virtio flags:\n", format_white_space, indent);
+#define _(n,i,st) \
+          if (t->virtio_ring_flags & (1 << VIRTIO_TRACE_F_##n)) \
+            s = format (s, "%U  %s %s\n", format_white_space, indent, #n, st);
+  foreach_virtio_trace_flags
+#undef _
+    s = format (s, "%U virtio_net_hdr first_desc_len %u\n",
+		format_white_space, indent, t->first_desc_len);
+
+  s = format (s, "%U   flags 0x%02x gso_type %u\n",
+	      format_white_space, indent,
+	      t->hdr.hdr.flags, t->hdr.hdr.gso_type);
+
+  if (vui->virtio_net_hdr_sz == 12)
+    s = format (s, "%U   num_buff %u",
+		format_white_space, indent, t->hdr.num_buffers);
+
+  return s;
+}
+
+static_always_inline u64
+vhost_user_is_packed_ring_supported (vhost_user_intf_t * vui)
+{
+  return (vui->features & VIRTIO_FEATURE (VIRTIO_F_RING_PACKED));
+}
+
+static_always_inline u64
+vhost_user_is_event_idx_supported (vhost_user_intf_t * vui)
+{
+  return (vui->features & VIRTIO_FEATURE (VIRTIO_RING_F_EVENT_IDX));
+}
+
+static_always_inline void
+vhost_user_kick (vlib_main_t * vm, vhost_user_vring_t * vq)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u64 x = 1;
+  int fd = UNIX_GET_FD (vq->callfd_idx);
+  int rv;
+
+  rv = write (fd, &x, sizeof (x));
+  if (PREDICT_FALSE (rv <= 0))
+    {
+      clib_unix_warning
+	("Error: Could not write to unix socket for callfd %d", fd);
+      return;
+    }
+
+  vq->n_since_last_int = 0;
+  vq->int_deadline = vlib_time_now (vm) + vum->coalesce_time;
+}
+
+static_always_inline u16
+vhost_user_avail_event_idx (vhost_user_vring_t * vq)
+{
+  volatile u16 *event_idx = (u16 *) & (vq->used->ring[vq->qsz_mask + 1]);
+
+  return *event_idx;
+}
+
+static_always_inline u16
+vhost_user_used_event_idx (vhost_user_vring_t * vq)
+{
+  volatile u16 *event_idx = (u16 *) & (vq->avail->ring[vq->qsz_mask + 1]);
+
+  return *event_idx;
+}
+
+static_always_inline u16
+vhost_user_need_event (u16 event_idx, u16 new_idx, u16 old_idx)
+{
+  return ((u16) (new_idx - event_idx - 1) < (u16) (new_idx - old_idx));
+}
+
+static_always_inline void
+vhost_user_send_call_event_idx (vlib_main_t * vm, vhost_user_vring_t * vq)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u8 first_kick = vq->first_kick;
+  u16 event_idx = vhost_user_used_event_idx (vq);
+
+  vq->first_kick = 1;
+  if (vhost_user_need_event (event_idx, vq->last_used_idx, vq->last_kick) ||
+      PREDICT_FALSE (!first_kick))
+    {
+      vhost_user_kick (vm, vq);
+      vq->last_kick = event_idx;
+    }
+  else
+    {
+      vq->n_since_last_int = 0;
+      vq->int_deadline = vlib_time_now (vm) + vum->coalesce_time;
+    }
+}
+
+static_always_inline void
+vhost_user_send_call_event_idx_packed (vlib_main_t * vm,
+				       vhost_user_vring_t * vq)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u8 first_kick = vq->first_kick;
+  u16 off_wrap;
+  u16 event_idx;
+  u16 new_idx = vq->last_used_idx;
+  u16 old_idx = vq->last_kick;
+
+  if (PREDICT_TRUE (vq->avail_event->flags == VRING_EVENT_F_DESC))
+    {
+      CLIB_COMPILER_BARRIER ();
+      off_wrap = vq->avail_event->off_wrap;
+      event_idx = off_wrap & 0x7fff;
+      if (vq->used_wrap_counter != (off_wrap >> 15))
+	event_idx -= (vq->qsz_mask + 1);
+
+      if (new_idx <= old_idx)
+	old_idx -= (vq->qsz_mask + 1);
+
+      vq->first_kick = 1;
+      vq->last_kick = event_idx;
+      if (vhost_user_need_event (event_idx, new_idx, old_idx) ||
+	  PREDICT_FALSE (!first_kick))
+	vhost_user_kick (vm, vq);
+      else
+	{
+	  vq->n_since_last_int = 0;
+	  vq->int_deadline = vlib_time_now (vm) + vum->coalesce_time;
+	}
+    }
+  else
+    vhost_user_kick (vm, vq);
+}
+
+static_always_inline void
+vhost_user_send_call (vlib_main_t * vm, vhost_user_intf_t * vui,
+		      vhost_user_vring_t * vq)
+{
+  if (vhost_user_is_event_idx_supported (vui))
+    {
+      if (vhost_user_is_packed_ring_supported (vui))
+	vhost_user_send_call_event_idx_packed (vm, vq);
+      else
+	vhost_user_send_call_event_idx (vm, vq);
+    }
+  else
+    vhost_user_kick (vm, vq);
+}
+
+static_always_inline u8
+vui_is_link_up (vhost_user_intf_t * vui)
+{
+  return vui->admin_up && vui->is_ready;
+}
+
+static_always_inline void
+vhost_user_update_gso_interface_count (vhost_user_intf_t * vui, u8 add)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  if (vui->enable_gso)
+    {
+      if (add)
+	{
+	  vum->gso_count++;
+	}
+      else
+	{
+	  ASSERT (vum->gso_count > 0);
+	  vum->gso_count--;
+	}
+    }
+}
+
+static_always_inline u8
+vhost_user_packed_desc_available (vhost_user_vring_t * vring, u16 idx)
+{
+  return (((vring->packed_desc[idx].flags & VRING_DESC_F_AVAIL) ==
+	   vring->avail_wrap_counter));
+}
+
+static_always_inline void
+vhost_user_advance_last_avail_idx (vhost_user_vring_t * vring)
+{
+  vring->last_avail_idx++;
+  if (PREDICT_FALSE ((vring->last_avail_idx & vring->qsz_mask) == 0))
+    {
+      vring->avail_wrap_counter ^= VRING_DESC_F_AVAIL;
+      vring->last_avail_idx = 0;
+    }
+}
+
+static_always_inline void
+vhost_user_advance_last_avail_table_idx (vhost_user_intf_t * vui,
+					 vhost_user_vring_t * vring,
+					 u8 chained)
+{
+  if (chained)
+    {
+      vnet_virtio_vring_packed_desc_t *desc_table = vring->packed_desc;
+
+      /* pick up the slot of the next avail idx */
+      while (desc_table[vring->last_avail_idx & vring->qsz_mask].flags &
+	     VRING_DESC_F_NEXT)
+	vhost_user_advance_last_avail_idx (vring);
+    }
+
+  vhost_user_advance_last_avail_idx (vring);
+}
+
+static_always_inline void
+vhost_user_undo_advanced_last_avail_idx (vhost_user_vring_t * vring)
+{
+  if (PREDICT_FALSE ((vring->last_avail_idx & vring->qsz_mask) == 0))
+    vring->avail_wrap_counter ^= VRING_DESC_F_AVAIL;
+
+  if (PREDICT_FALSE (vring->last_avail_idx == 0))
+    vring->last_avail_idx = vring->qsz_mask;
+  else
+    vring->last_avail_idx--;
+}
+
+static_always_inline void
+vhost_user_dequeue_descs (vhost_user_vring_t *rxvq,
+			  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr,
+			  u16 *n_descs_processed)
+{
+  u16 i;
+
+  *n_descs_processed -= (hdr->num_buffers - 1);
+  for (i = 0; i < hdr->num_buffers - 1; i++)
+    vhost_user_undo_advanced_last_avail_idx (rxvq);
+}
+
+static_always_inline void
+vhost_user_dequeue_chained_descs (vhost_user_vring_t * rxvq,
+				  u16 * n_descs_processed)
+{
+  while (*n_descs_processed)
+    {
+      vhost_user_undo_advanced_last_avail_idx (rxvq);
+      (*n_descs_processed)--;
+    }
+}
+
+static_always_inline void
+vhost_user_advance_last_used_idx (vhost_user_vring_t * vring)
+{
+  vring->last_used_idx++;
+  if (PREDICT_FALSE ((vring->last_used_idx & vring->qsz_mask) == 0))
+    {
+      vring->used_wrap_counter ^= 1;
+      vring->last_used_idx = 0;
+    }
+}
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user_input.c b/src/plugins/vhost/vhost_user_input.c
new file mode 100644
index 00000000000..c083f43ba7c
--- /dev/null
+++ b/src/plugins/vhost/vhost_user_input.c
@@ -0,0 +1,1474 @@
+/*
+ *------------------------------------------------------------------
+ * vhost-user-input
+ *
+ * Copyright (c) 2014-2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#include <fcntl.h>		/* for open */
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/uio.h>		/* for iovec */
+#include <netinet/in.h>
+#include <sys/vfs.h>
+
+#include <linux/if_arp.h>
+#include <linux/if_tun.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/devices.h>
+#include <vnet/feature/feature.h>
+#include <vnet/udp/udp_packet.h>
+#include <vnet/tcp/tcp_packet.h>
+#include <vnet/interface/rx_queue_funcs.h>
+
+#include <vhost/vhost_user.h>
+#include <vhost/vhost_user_inline.h>
+
+#include <vnet/ip/ip4_packet.h>
+#include <vnet/ip/ip6_packet.h>
+
+/*
+ * When an RX queue is down but active, received packets
+ * must be discarded. This value controls up to how many
+ * packets will be discarded during each round.
+ */
+#define VHOST_USER_DOWN_DISCARD_COUNT 256
+
+/*
+ * When the number of available buffers gets under this threshold,
+ * RX node will start discarding packets.
+ */
+#define VHOST_USER_RX_BUFFER_STARVATION 32
+
+/*
+ * On the receive side, the host should free descriptors as soon
+ * as possible in order to avoid TX drop in the VM.
+ * This value controls the number of copy operations that are stacked
+ * before copy is done for all and descriptors are given back to
+ * the guest.
+ * The value 64 was obtained by testing (48 and 128 were not as good).
+ */
+#define VHOST_USER_RX_COPY_THRESHOLD 64
+
+extern vlib_node_registration_t vhost_user_input_node;
+
+#define foreach_vhost_user_input_func_error      \
+  _(NO_ERROR, "no error")  \
+  _(NO_BUFFER, "no available buffer")  \
+  _(MMAP_FAIL, "mmap failure")  \
+  _(INDIRECT_OVERFLOW, "indirect descriptor overflows table")  \
+  _(UNDERSIZED_FRAME, "undersized ethernet frame received (< 14 bytes)") \
+  _(NOT_READY, "vhost interface not ready or down") \
+  _(FULL_RX_QUEUE, "full rx queue (possible driver tx drop)")
+
+typedef enum
+{
+#define _(f,s) VHOST_USER_INPUT_FUNC_ERROR_##f,
+  foreach_vhost_user_input_func_error
+#undef _
+    VHOST_USER_INPUT_FUNC_N_ERROR,
+} vhost_user_input_func_error_t;
+
+static __clib_unused char *vhost_user_input_func_error_strings[] = {
+#define _(n,s) s,
+  foreach_vhost_user_input_func_error
+#undef _
+};
+
+static_always_inline void
+vhost_user_rx_trace (vhost_trace_t * t,
+		     vhost_user_intf_t * vui, u16 qid,
+		     vlib_buffer_t * b, vhost_user_vring_t * txvq,
+		     u16 last_avail_idx)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u32 desc_current = txvq->avail->ring[last_avail_idx & txvq->qsz_mask];
+  vnet_virtio_vring_desc_t *hdr_desc = 0;
+  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr;
+  u32 hint = 0;
+
+  clib_memset (t, 0, sizeof (*t));
+  t->device_index = vui - vum->vhost_user_interfaces;
+  t->qid = qid;
+
+  hdr_desc = &txvq->desc[desc_current];
+  if (txvq->desc[desc_current].flags & VRING_DESC_F_INDIRECT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_INDIRECT;
+      /* Header is the first here */
+      hdr_desc = map_guest_mem (vui, txvq->desc[desc_current].addr, &hint);
+    }
+  if (txvq->desc[desc_current].flags & VRING_DESC_F_NEXT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+    }
+  if (!(txvq->desc[desc_current].flags & VRING_DESC_F_NEXT) &&
+      !(txvq->desc[desc_current].flags & VRING_DESC_F_INDIRECT))
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SINGLE_DESC;
+    }
+
+  t->first_desc_len = hdr_desc ? hdr_desc->len : 0;
+
+  if (!hdr_desc || !(hdr = map_guest_mem (vui, hdr_desc->addr, &hint)))
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_MAP_ERROR;
+    }
+  else
+    {
+      u32 len = vui->virtio_net_hdr_sz;
+      memcpy (&t->hdr, hdr, len > hdr_desc->len ? hdr_desc->len : len);
+    }
+}
+
+static_always_inline u32
+vhost_user_input_copy (vhost_user_intf_t * vui, vhost_copy_t * cpy,
+		       u16 copy_len, u32 * map_hint)
+{
+  void *src0, *src1, *src2, *src3;
+  if (PREDICT_TRUE (copy_len >= 4))
+    {
+      if (PREDICT_FALSE (!(src2 = map_guest_mem (vui, cpy[0].src, map_hint))))
+	return 1;
+      if (PREDICT_FALSE (!(src3 = map_guest_mem (vui, cpy[1].src, map_hint))))
+	return 1;
+
+      while (PREDICT_TRUE (copy_len >= 4))
+	{
+	  src0 = src2;
+	  src1 = src3;
+
+	  if (PREDICT_FALSE
+	      (!(src2 = map_guest_mem (vui, cpy[2].src, map_hint))))
+	    return 1;
+	  if (PREDICT_FALSE
+	      (!(src3 = map_guest_mem (vui, cpy[3].src, map_hint))))
+	    return 1;
+
+	  clib_prefetch_load (src2);
+	  clib_prefetch_load (src3);
+
+	  clib_memcpy_fast ((void *) cpy[0].dst, src0, cpy[0].len);
+	  clib_memcpy_fast ((void *) cpy[1].dst, src1, cpy[1].len);
+	  copy_len -= 2;
+	  cpy += 2;
+	}
+    }
+  while (copy_len)
+    {
+      if (PREDICT_FALSE (!(src0 = map_guest_mem (vui, cpy->src, map_hint))))
+	return 1;
+      clib_memcpy_fast ((void *) cpy->dst, src0, cpy->len);
+      copy_len -= 1;
+      cpy += 1;
+    }
+  return 0;
+}
+
+/**
+ * Try to discard packets from the tx ring (VPP RX path).
+ * Returns the number of discarded packets.
+ */
+static_always_inline u32
+vhost_user_rx_discard_packet (vlib_main_t * vm,
+			      vhost_user_intf_t * vui,
+			      vhost_user_vring_t * txvq, u32 discard_max)
+{
+  /*
+   * On the RX side, each packet corresponds to one descriptor
+   * (it is the same whether it is a shallow descriptor, chained, or indirect).
+   * Therefore, discarding a packet is like discarding a descriptor.
+   */
+  u32 discarded_packets = 0;
+  u32 avail_idx = txvq->avail->idx;
+  u16 mask = txvq->qsz_mask;
+  u16 last_avail_idx = txvq->last_avail_idx;
+  u16 last_used_idx = txvq->last_used_idx;
+  while (discarded_packets != discard_max)
+    {
+      if (avail_idx == last_avail_idx)
+	goto out;
+
+      u16 desc_chain_head = txvq->avail->ring[last_avail_idx & mask];
+      last_avail_idx++;
+      txvq->used->ring[last_used_idx & mask].id = desc_chain_head;
+      txvq->used->ring[last_used_idx & mask].len = 0;
+      vhost_user_log_dirty_ring (vui, txvq, ring[last_used_idx & mask]);
+      last_used_idx++;
+      discarded_packets++;
+    }
+
+out:
+  txvq->last_avail_idx = last_avail_idx;
+  txvq->last_used_idx = last_used_idx;
+  CLIB_MEMORY_STORE_BARRIER ();
+  txvq->used->idx = txvq->last_used_idx;
+  vhost_user_log_dirty_ring (vui, txvq, idx);
+  return discarded_packets;
+}
+
+/*
+ * In case of overflow, we need to rewind the array of allocated buffers.
+ */
+static_always_inline void
+vhost_user_input_rewind_buffers (vlib_main_t * vm,
+				 vhost_cpu_t * cpu, vlib_buffer_t * b_head)
+{
+  u32 bi_current = cpu->rx_buffers[cpu->rx_buffers_len];
+  vlib_buffer_t *b_current = vlib_get_buffer (vm, bi_current);
+  b_current->current_length = 0;
+  b_current->flags = 0;
+  while (b_current != b_head)
+    {
+      cpu->rx_buffers_len++;
+      bi_current = cpu->rx_buffers[cpu->rx_buffers_len];
+      b_current = vlib_get_buffer (vm, bi_current);
+      b_current->current_length = 0;
+      b_current->flags = 0;
+    }
+  cpu->rx_buffers_len++;
+}
+
+static_always_inline void
+vhost_user_handle_rx_offload (vlib_buffer_t *b0, u8 *b0_data,
+			      vnet_virtio_net_hdr_t *hdr)
+{
+  u8 l4_hdr_sz = 0;
+  u8 l4_proto = 0;
+  ethernet_header_t *eh = (ethernet_header_t *) b0_data;
+  u16 ethertype = clib_net_to_host_u16 (eh->type);
+  u16 l2hdr_sz = sizeof (ethernet_header_t);
+  vnet_buffer_oflags_t oflags = 0;
+
+  if (ethernet_frame_is_tagged (ethertype))
+    {
+      ethernet_vlan_header_t *vlan = (ethernet_vlan_header_t *) (eh + 1);
+
+      ethertype = clib_net_to_host_u16 (vlan->type);
+      l2hdr_sz += sizeof (*vlan);
+      if (ethertype == ETHERNET_TYPE_VLAN)
+	{
+	  vlan++;
+	  ethertype = clib_net_to_host_u16 (vlan->type);
+	  l2hdr_sz += sizeof (*vlan);
+	}
+    }
+  vnet_buffer (b0)->l2_hdr_offset = 0;
+  vnet_buffer (b0)->l3_hdr_offset = l2hdr_sz;
+  vnet_buffer (b0)->l4_hdr_offset = hdr->csum_start;
+  b0->flags |= (VNET_BUFFER_F_L2_HDR_OFFSET_VALID |
+		VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
+		VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
+
+  if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP4))
+    {
+      ip4_header_t *ip4 = (ip4_header_t *) (b0_data + l2hdr_sz);
+      l4_proto = ip4->protocol;
+      b0->flags |= VNET_BUFFER_F_IS_IP4;
+      oflags |= VNET_BUFFER_OFFLOAD_F_IP_CKSUM;
+    }
+  else if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP6))
+    {
+      ip6_header_t *ip6 = (ip6_header_t *) (b0_data + l2hdr_sz);
+      l4_proto = ip6->protocol;
+      b0->flags |= VNET_BUFFER_F_IS_IP6;
+    }
+
+  if (l4_proto == IP_PROTOCOL_TCP)
+    {
+      tcp_header_t *tcp = (tcp_header_t *)
+	(b0_data + vnet_buffer (b0)->l4_hdr_offset);
+      l4_hdr_sz = tcp_header_bytes (tcp);
+      oflags |= VNET_BUFFER_OFFLOAD_F_TCP_CKSUM;
+    }
+  else if (l4_proto == IP_PROTOCOL_UDP)
+    {
+      l4_hdr_sz = sizeof (udp_header_t);
+      oflags |= VNET_BUFFER_OFFLOAD_F_UDP_CKSUM;
+    }
+
+  if (hdr->gso_type == VIRTIO_NET_HDR_GSO_UDP)
+    {
+      vnet_buffer2 (b0)->gso_size = hdr->gso_size;
+      vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
+      b0->flags |= VNET_BUFFER_F_GSO;
+    }
+  else if (hdr->gso_type == VIRTIO_NET_HDR_GSO_TCPV4)
+    {
+      vnet_buffer2 (b0)->gso_size = hdr->gso_size;
+      vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
+      b0->flags |= (VNET_BUFFER_F_GSO | VNET_BUFFER_F_IS_IP4);
+    }
+  else if (hdr->gso_type == VIRTIO_NET_HDR_GSO_TCPV6)
+    {
+      vnet_buffer2 (b0)->gso_size = hdr->gso_size;
+      vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
+      b0->flags |= (VNET_BUFFER_F_GSO | VNET_BUFFER_F_IS_IP6);
+    }
+
+  if (oflags)
+    vnet_buffer_offload_flags_set (b0, oflags);
+}
+
+static_always_inline void
+vhost_user_input_do_interrupt (vlib_main_t * vm, vhost_user_intf_t * vui,
+			       vhost_user_vring_t * txvq,
+			       vhost_user_vring_t * rxvq)
+{
+  f64 now = vlib_time_now (vm);
+
+  if ((txvq->n_since_last_int) && (txvq->int_deadline < now))
+    vhost_user_send_call (vm, vui, txvq);
+
+  if ((rxvq->n_since_last_int) && (rxvq->int_deadline < now))
+    vhost_user_send_call (vm, vui, rxvq);
+}
+
+static_always_inline void
+vhost_user_input_setup_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
+			      vhost_user_intf_t * vui,
+			      u32 * current_config_index, u32 * next_index,
+			      u32 ** to_next, u32 * n_left_to_next)
+{
+  vnet_feature_main_t *fm = &feature_main;
+  u8 feature_arc_idx = fm->device_input_feature_arc_index;
+
+  if (PREDICT_FALSE (vnet_have_features (feature_arc_idx, vui->sw_if_index)))
+    {
+      vnet_feature_config_main_t *cm;
+      cm = &fm->feature_config_mains[feature_arc_idx];
+      *current_config_index = vec_elt (cm->config_index_by_sw_if_index,
+				       vui->sw_if_index);
+      vnet_get_config_data (&cm->config_main, current_config_index,
+			    next_index, 0);
+    }
+
+  vlib_get_new_next_frame (vm, node, *next_index, *to_next, *n_left_to_next);
+
+  if (*next_index == VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT)
+    {
+      /* give some hints to ethernet-input */
+      vlib_next_frame_t *nf;
+      vlib_frame_t *f;
+      ethernet_input_frame_t *ef;
+      nf = vlib_node_runtime_get_next_frame (vm, node, *next_index);
+      f = vlib_get_frame (vm, nf->frame);
+      f->flags = ETH_INPUT_FRAME_F_SINGLE_SW_IF_IDX;
+
+      ef = vlib_frame_scalar_args (f);
+      ef->sw_if_index = vui->sw_if_index;
+      ef->hw_if_index = vui->hw_if_index;
+      vlib_frame_no_append (f);
+    }
+}
+
+static_always_inline u32
+vhost_user_if_input (vlib_main_t *vm, vhost_user_main_t *vum,
+		     vhost_user_intf_t *vui, u16 qid,
+		     vlib_node_runtime_t *node, u8 enable_csum)
+{
+  vhost_user_vring_t *txvq = &vui->vrings[VHOST_VRING_IDX_TX (qid)];
+  vnet_feature_main_t *fm = &feature_main;
+  u16 n_rx_packets = 0;
+  u32 n_rx_bytes = 0;
+  u16 n_left;
+  u32 n_left_to_next, *to_next;
+  u32 next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
+  u32 n_trace = vlib_get_trace_count (vm, node);
+  u32 buffer_data_size = vlib_buffer_get_default_data_size (vm);
+  u32 map_hint = 0;
+  vhost_cpu_t *cpu = &vum->cpus[vm->thread_index];
+  u16 copy_len = 0;
+  u8 feature_arc_idx = fm->device_input_feature_arc_index;
+  u32 current_config_index = ~(u32) 0;
+  u16 mask = txvq->qsz_mask;
+
+  /* The descriptor table is not ready yet */
+  if (PREDICT_FALSE (txvq->avail == 0))
+    goto done;
+
+  {
+    /* do we have pending interrupts ? */
+    vhost_user_vring_t *rxvq = &vui->vrings[VHOST_VRING_IDX_RX (qid)];
+    vhost_user_input_do_interrupt (vm, vui, txvq, rxvq);
+  }
+
+  /*
+   * For adaptive mode, it is optimized to reduce interrupts.
+   * If the scheduler switches the input node to polling due
+   * to burst of traffic, we tell the driver no interrupt.
+   * When the traffic subsides, the scheduler switches the node back to
+   * interrupt mode. We must tell the driver we want interrupt.
+   */
+  if (PREDICT_FALSE (txvq->mode == VNET_HW_IF_RX_MODE_ADAPTIVE))
+    {
+      if ((node->flags &
+	   VLIB_NODE_FLAG_SWITCH_FROM_POLLING_TO_INTERRUPT_MODE) ||
+	  !(node->flags &
+	    VLIB_NODE_FLAG_SWITCH_FROM_INTERRUPT_TO_POLLING_MODE))
+	/* Tell driver we want notification */
+	txvq->used->flags = 0;
+      else
+	/* Tell driver we don't want notification */
+	txvq->used->flags = VRING_USED_F_NO_NOTIFY;
+    }
+
+  if (PREDICT_FALSE (txvq->avail->flags & 0xFFFE))
+    goto done;
+
+  n_left = (u16) (txvq->avail->idx - txvq->last_avail_idx);
+
+  /* nothing to do */
+  if (PREDICT_FALSE (n_left == 0))
+    goto done;
+
+  if (PREDICT_FALSE (!vui->admin_up || !(txvq->enabled)))
+    {
+      /*
+       * Discard input packet if interface is admin down or vring is not
+       * enabled.
+       * "For example, for a networking device, in the disabled state
+       * client must not supply any new RX packets, but must process
+       * and discard any TX packets."
+       */
+      vhost_user_rx_discard_packet (vm, vui, txvq,
+				    VHOST_USER_DOWN_DISCARD_COUNT);
+      goto done;
+    }
+
+  if (PREDICT_FALSE (n_left == (mask + 1)))
+    {
+      /*
+       * Informational error logging when VPP is not
+       * receiving packets fast enough.
+       */
+      vlib_error_count (vm, node->node_index,
+			VHOST_USER_INPUT_FUNC_ERROR_FULL_RX_QUEUE, 1);
+    }
+
+  if (n_left > VLIB_FRAME_SIZE)
+    n_left = VLIB_FRAME_SIZE;
+
+  /*
+   * For small packets (<2kB), we will not need more than one vlib buffer
+   * per packet. In case packets are bigger, we will just yield at some point
+   * in the loop and come back later. This is not an issue as for big packet,
+   * processing cost really comes from the memory copy.
+   * The assumption is that big packets will fit in 40 buffers.
+   */
+  if (PREDICT_FALSE (cpu->rx_buffers_len < n_left + 1 ||
+		     cpu->rx_buffers_len < 40))
+    {
+      u32 curr_len = cpu->rx_buffers_len;
+      cpu->rx_buffers_len +=
+	vlib_buffer_alloc (vm, cpu->rx_buffers + curr_len,
+			   VHOST_USER_RX_BUFFERS_N - curr_len);
+
+      if (PREDICT_FALSE
+	  (cpu->rx_buffers_len < VHOST_USER_RX_BUFFER_STARVATION))
+	{
+	  /* In case of buffer starvation, discard some packets from the queue
+	   * and log the event.
+	   * We keep doing best effort for the remaining packets. */
+	  u32 flush = (n_left + 1 > cpu->rx_buffers_len) ?
+	    n_left + 1 - cpu->rx_buffers_len : 1;
+	  flush = vhost_user_rx_discard_packet (vm, vui, txvq, flush);
+
+	  n_left -= flush;
+	  vlib_increment_simple_counter (vnet_main.
+					 interface_main.sw_if_counters +
+					 VNET_INTERFACE_COUNTER_DROP,
+					 vm->thread_index, vui->sw_if_index,
+					 flush);
+
+	  vlib_error_count (vm, vhost_user_input_node.index,
+			    VHOST_USER_INPUT_FUNC_ERROR_NO_BUFFER, flush);
+	}
+    }
+
+  vhost_user_input_setup_frame (vm, node, vui, &current_config_index,
+				&next_index, &to_next, &n_left_to_next);
+
+  u16 last_avail_idx = txvq->last_avail_idx;
+  u16 last_used_idx = txvq->last_used_idx;
+
+  while (n_left > 0)
+    {
+      vlib_buffer_t *b_head, *b_current;
+      u32 bi_current;
+      u16 desc_current;
+      u32 desc_data_offset;
+      vnet_virtio_vring_desc_t *desc_table = txvq->desc;
+
+      if (PREDICT_FALSE (cpu->rx_buffers_len <= 1))
+	{
+	  /* Not enough rx_buffers
+	   * Note: We yeld on 1 so we don't need to do an additional
+	   * check for the next buffer prefetch.
+	   */
+	  n_left = 0;
+	  break;
+	}
+
+      desc_current = txvq->avail->ring[last_avail_idx & mask];
+      cpu->rx_buffers_len--;
+      bi_current = cpu->rx_buffers[cpu->rx_buffers_len];
+      b_head = b_current = vlib_get_buffer (vm, bi_current);
+      to_next[0] = bi_current;	//We do that now so we can forget about bi_current
+      to_next++;
+      n_left_to_next--;
+
+      vlib_prefetch_buffer_with_index
+	(vm, cpu->rx_buffers[cpu->rx_buffers_len - 1], LOAD);
+
+      /* Just preset the used descriptor id and length for later */
+      txvq->used->ring[last_used_idx & mask].id = desc_current;
+      txvq->used->ring[last_used_idx & mask].len = 0;
+      vhost_user_log_dirty_ring (vui, txvq, ring[last_used_idx & mask]);
+
+      /* The buffer should already be initialized */
+      b_head->total_length_not_including_first_buffer = 0;
+      b_head->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
+
+      if (PREDICT_FALSE
+	  (n_trace > 0 && vlib_trace_buffer (vm, node, next_index, b_head,
+					     /* follow_chain */ 0)))
+	{
+	  vhost_trace_t *t0 =
+	    vlib_add_trace (vm, node, b_head, sizeof (t0[0]));
+	  vhost_user_rx_trace (t0, vui, qid, b_head, txvq, last_avail_idx);
+	  n_trace--;
+	  vlib_set_trace_count (vm, node, n_trace);
+	}
+
+      /* This depends on the setup but is very consistent
+       * So I think the CPU branch predictor will make a pretty good job
+       * at optimizing the decision. */
+      if (txvq->desc[desc_current].flags & VRING_DESC_F_INDIRECT)
+	{
+	  desc_table = map_guest_mem (vui, txvq->desc[desc_current].addr,
+				      &map_hint);
+	  desc_current = 0;
+	  if (PREDICT_FALSE (desc_table == 0))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL, 1);
+	      goto out;
+	    }
+	}
+
+      desc_data_offset = vui->virtio_net_hdr_sz;
+
+      if (enable_csum)
+	{
+	  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr;
+	  u8 *b_data;
+	  u16 current;
+
+	  hdr = map_guest_mem (vui, desc_table[desc_current].addr, &map_hint);
+	  if (PREDICT_FALSE (hdr == 0))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL, 1);
+	      goto out;
+	    }
+	  if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)
+	    {
+	      if ((desc_data_offset == desc_table[desc_current].len) &&
+		  (desc_table[desc_current].flags & VRING_DESC_F_NEXT))
+		{
+		  current = desc_table[desc_current].next;
+		  b_data = map_guest_mem (vui, desc_table[current].addr,
+					  &map_hint);
+		  if (PREDICT_FALSE (b_data == 0))
+		    {
+		      vlib_error_count (vm, node->node_index,
+					VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL,
+					1);
+		      goto out;
+		    }
+		}
+	      else
+		b_data = (u8 *) hdr + desc_data_offset;
+
+	      vhost_user_handle_rx_offload (b_head, b_data, &hdr->hdr);
+	    }
+	}
+
+      while (1)
+	{
+	  /* Get more input if necessary. Or end of packet. */
+	  if (desc_data_offset == desc_table[desc_current].len)
+	    {
+	      if (PREDICT_FALSE (desc_table[desc_current].flags &
+				 VRING_DESC_F_NEXT))
+		{
+		  desc_current = desc_table[desc_current].next;
+		  desc_data_offset = 0;
+		}
+	      else
+		{
+		  goto out;
+		}
+	    }
+
+	  /* Get more output if necessary. Or end of packet. */
+	  if (PREDICT_FALSE (b_current->current_length == buffer_data_size))
+	    {
+	      if (PREDICT_FALSE (cpu->rx_buffers_len == 0))
+		{
+		  /* Cancel speculation */
+		  to_next--;
+		  n_left_to_next++;
+
+		  /*
+		   * Checking if there are some left buffers.
+		   * If not, just rewind the used buffers and stop.
+		   * Note: Scheduled copies are not cancelled. This is
+		   * not an issue as they would still be valid. Useless,
+		   * but valid.
+		   */
+		  vhost_user_input_rewind_buffers (vm, cpu, b_head);
+		  n_left = 0;
+		  goto stop;
+		}
+
+	      /* Get next output */
+	      cpu->rx_buffers_len--;
+	      u32 bi_next = cpu->rx_buffers[cpu->rx_buffers_len];
+	      b_current->next_buffer = bi_next;
+	      b_current->flags |= VLIB_BUFFER_NEXT_PRESENT;
+	      bi_current = bi_next;
+	      b_current = vlib_get_buffer (vm, bi_current);
+	    }
+
+	  /* Prepare a copy order executed later for the data */
+	  ASSERT (copy_len < VHOST_USER_COPY_ARRAY_N);
+	  vhost_copy_t *cpy = &cpu->copy[copy_len];
+	  copy_len++;
+	  u32 desc_data_l = desc_table[desc_current].len - desc_data_offset;
+	  cpy->len = buffer_data_size - b_current->current_length;
+	  cpy->len = (cpy->len > desc_data_l) ? desc_data_l : cpy->len;
+	  cpy->dst = (uword) (vlib_buffer_get_current (b_current) +
+			      b_current->current_length);
+	  cpy->src = desc_table[desc_current].addr + desc_data_offset;
+
+	  desc_data_offset += cpy->len;
+
+	  b_current->current_length += cpy->len;
+	  b_head->total_length_not_including_first_buffer += cpy->len;
+	}
+
+    out:
+
+      n_rx_bytes += b_head->total_length_not_including_first_buffer;
+      n_rx_packets++;
+
+      b_head->total_length_not_including_first_buffer -=
+	b_head->current_length;
+
+      /* consume the descriptor and return it as used */
+      last_avail_idx++;
+      last_used_idx++;
+
+      vnet_buffer (b_head)->sw_if_index[VLIB_RX] = vui->sw_if_index;
+      vnet_buffer (b_head)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+      b_head->error = 0;
+
+      if (current_config_index != ~(u32) 0)
+	{
+	  b_head->current_config_index = current_config_index;
+	  vnet_buffer (b_head)->feature_arc_index = feature_arc_idx;
+	}
+
+      n_left--;
+
+      /*
+       * Although separating memory copies from virtio ring parsing
+       * is beneficial, we can offer to perform the copies from time
+       * to time in order to free some space in the ring.
+       */
+      if (PREDICT_FALSE (copy_len >= VHOST_USER_RX_COPY_THRESHOLD))
+	{
+	  if (PREDICT_FALSE (vhost_user_input_copy (vui, cpu->copy,
+						    copy_len, &map_hint)))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL, 1);
+	    }
+	  copy_len = 0;
+
+	  /* give buffers back to driver */
+	  CLIB_MEMORY_STORE_BARRIER ();
+	  txvq->used->idx = last_used_idx;
+	  vhost_user_log_dirty_ring (vui, txvq, idx);
+	}
+    }
+stop:
+  vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+
+  txvq->last_used_idx = last_used_idx;
+  txvq->last_avail_idx = last_avail_idx;
+
+  /* Do the memory copies */
+  if (PREDICT_FALSE (vhost_user_input_copy (vui, cpu->copy, copy_len,
+					    &map_hint)))
+    {
+      vlib_error_count (vm, node->node_index,
+			VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL, 1);
+    }
+
+  /* give buffers back to driver */
+  CLIB_MEMORY_STORE_BARRIER ();
+  txvq->used->idx = txvq->last_used_idx;
+  vhost_user_log_dirty_ring (vui, txvq, idx);
+
+  /* interrupt (call) handling */
+  if ((txvq->callfd_idx != ~0) &&
+      !(txvq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+    {
+      txvq->n_since_last_int += n_rx_packets;
+
+      if (txvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, vui, txvq);
+    }
+
+  /* increase rx counters */
+  vlib_increment_combined_counter
+    (vnet_main.interface_main.combined_sw_if_counters
+     + VNET_INTERFACE_COUNTER_RX, vm->thread_index, vui->sw_if_index,
+     n_rx_packets, n_rx_bytes);
+
+  vnet_device_increment_rx_packets (vm->thread_index, n_rx_packets);
+
+done:
+  return n_rx_packets;
+}
+
+static_always_inline void
+vhost_user_mark_desc_consumed (vhost_user_intf_t * vui,
+			       vhost_user_vring_t * txvq, u16 desc_head,
+			       u16 n_descs_processed)
+{
+  vnet_virtio_vring_packed_desc_t *desc_table = txvq->packed_desc;
+  u16 desc_idx;
+  u16 mask = txvq->qsz_mask;
+
+  for (desc_idx = 0; desc_idx < n_descs_processed; desc_idx++)
+    {
+      if (txvq->used_wrap_counter)
+	desc_table[(desc_head + desc_idx) & mask].flags |=
+	  (VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+      else
+	desc_table[(desc_head + desc_idx) & mask].flags &=
+	  ~(VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+      vhost_user_advance_last_used_idx (txvq);
+    }
+}
+
+static_always_inline void
+vhost_user_rx_trace_packed (vhost_trace_t * t, vhost_user_intf_t * vui,
+			    u16 qid, vhost_user_vring_t * txvq,
+			    u16 desc_current)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vnet_virtio_vring_packed_desc_t *hdr_desc;
+  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr;
+  u32 hint = 0;
+
+  clib_memset (t, 0, sizeof (*t));
+  t->device_index = vui - vum->vhost_user_interfaces;
+  t->qid = qid;
+
+  hdr_desc = &txvq->packed_desc[desc_current];
+  if (txvq->packed_desc[desc_current].flags & VRING_DESC_F_INDIRECT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_INDIRECT;
+      /* Header is the first here */
+      hdr_desc = map_guest_mem (vui, txvq->packed_desc[desc_current].addr,
+				&hint);
+    }
+  if (txvq->packed_desc[desc_current].flags & VRING_DESC_F_NEXT)
+    t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+
+  if (!(txvq->packed_desc[desc_current].flags & VRING_DESC_F_NEXT) &&
+      !(txvq->packed_desc[desc_current].flags & VRING_DESC_F_INDIRECT))
+    t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SINGLE_DESC;
+
+  t->first_desc_len = hdr_desc ? hdr_desc->len : 0;
+
+  if (!hdr_desc || !(hdr = map_guest_mem (vui, hdr_desc->addr, &hint)))
+    t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_MAP_ERROR;
+  else
+    {
+      u32 len = vui->virtio_net_hdr_sz;
+      clib_memcpy_fast (&t->hdr, hdr,
+			len > hdr_desc->len ? hdr_desc->len : len);
+    }
+}
+
+static_always_inline u32
+vhost_user_rx_discard_packet_packed (vlib_main_t * vm,
+				     vhost_user_intf_t * vui,
+				     vhost_user_vring_t * txvq,
+				     u32 discard_max)
+{
+  u32 discarded_packets = 0;
+  u16 mask = txvq->qsz_mask;
+  u16 desc_current, desc_head;
+
+  desc_head = desc_current = txvq->last_used_idx & mask;
+
+  /*
+   * On the RX side, each packet corresponds to one descriptor
+   * (it is the same whether it is a shallow descriptor, chained, or indirect).
+   * Therefore, discarding a packet is like discarding a descriptor.
+   */
+  while ((discarded_packets != discard_max) &&
+	 vhost_user_packed_desc_available (txvq, desc_current))
+    {
+      vhost_user_advance_last_avail_idx (txvq);
+      discarded_packets++;
+      desc_current = (desc_current + 1) & mask;
+    }
+
+  if (PREDICT_TRUE (discarded_packets))
+    vhost_user_mark_desc_consumed (vui, txvq, desc_head, discarded_packets);
+  return (discarded_packets);
+}
+
+static_always_inline u32
+vhost_user_input_copy_packed (vhost_user_intf_t * vui, vhost_copy_t * cpy,
+			      u16 copy_len, u32 * map_hint)
+{
+  void *src0, *src1, *src2, *src3, *src4, *src5, *src6, *src7;
+  u8 bad;
+  u32 rc = VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR;
+
+  if (PREDICT_TRUE (copy_len >= 8))
+    {
+      src4 = map_guest_mem (vui, cpy[0].src, map_hint);
+      src5 = map_guest_mem (vui, cpy[1].src, map_hint);
+      src6 = map_guest_mem (vui, cpy[2].src, map_hint);
+      src7 = map_guest_mem (vui, cpy[3].src, map_hint);
+      bad = (src4 == 0) + (src5 == 0) + (src6 == 0) + (src7 == 0);
+      if (PREDICT_FALSE (bad))
+	goto one_by_one;
+      clib_prefetch_load (src4);
+      clib_prefetch_load (src5);
+      clib_prefetch_load (src6);
+      clib_prefetch_load (src7);
+
+      while (PREDICT_TRUE (copy_len >= 8))
+	{
+	  src0 = src4;
+	  src1 = src5;
+	  src2 = src6;
+	  src3 = src7;
+
+	  src4 = map_guest_mem (vui, cpy[4].src, map_hint);
+	  src5 = map_guest_mem (vui, cpy[5].src, map_hint);
+	  src6 = map_guest_mem (vui, cpy[6].src, map_hint);
+	  src7 = map_guest_mem (vui, cpy[7].src, map_hint);
+	  bad = (src4 == 0) + (src5 == 0) + (src6 == 0) + (src7 == 0);
+	  if (PREDICT_FALSE (bad))
+	    break;
+
+	  clib_prefetch_load (src4);
+	  clib_prefetch_load (src5);
+	  clib_prefetch_load (src6);
+	  clib_prefetch_load (src7);
+
+	  clib_memcpy_fast ((void *) cpy[0].dst, src0, cpy[0].len);
+	  clib_memcpy_fast ((void *) cpy[1].dst, src1, cpy[1].len);
+	  clib_memcpy_fast ((void *) cpy[2].dst, src2, cpy[2].len);
+	  clib_memcpy_fast ((void *) cpy[3].dst, src3, cpy[3].len);
+	  copy_len -= 4;
+	  cpy += 4;
+	}
+    }
+
+one_by_one:
+  while (copy_len)
+    {
+      if (PREDICT_FALSE (!(src0 = map_guest_mem (vui, cpy->src, map_hint))))
+	{
+	  rc = VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL;
+	  break;
+	}
+      clib_memcpy_fast ((void *) cpy->dst, src0, cpy->len);
+      copy_len -= 1;
+      cpy += 1;
+    }
+  return rc;
+}
+
+static_always_inline u32
+vhost_user_do_offload (vhost_user_intf_t *vui,
+		       vnet_virtio_vring_packed_desc_t *desc_table,
+		       u16 desc_current, u16 mask, vlib_buffer_t *b_head,
+		       u32 *map_hint)
+{
+  u32 rc = VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR;
+  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr;
+  u8 *b_data;
+  u32 desc_data_offset = vui->virtio_net_hdr_sz;
+
+  hdr = map_guest_mem (vui, desc_table[desc_current].addr, map_hint);
+  if (PREDICT_FALSE (hdr == 0))
+    rc = VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL;
+  else if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)
+    {
+      if (desc_data_offset == desc_table[desc_current].len)
+	{
+	  desc_current = (desc_current + 1) & mask;
+	  b_data =
+	    map_guest_mem (vui, desc_table[desc_current].addr, map_hint);
+	  if (PREDICT_FALSE (b_data == 0))
+	    rc = VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL;
+	  else
+	    vhost_user_handle_rx_offload (b_head, b_data, &hdr->hdr);
+	}
+      else
+	{
+	  b_data = (u8 *) hdr + desc_data_offset;
+	  vhost_user_handle_rx_offload (b_head, b_data, &hdr->hdr);
+	}
+    }
+
+  return rc;
+}
+
+static_always_inline u32
+vhost_user_compute_buffers_required (u32 desc_len, u32 buffer_data_size)
+{
+  div_t result;
+  u32 buffers_required;
+
+  if (PREDICT_TRUE (buffer_data_size == 2048))
+    {
+      buffers_required = desc_len >> 11;
+      if ((desc_len & 2047) != 0)
+	buffers_required++;
+      return (buffers_required);
+    }
+
+  if (desc_len < buffer_data_size)
+    return 1;
+
+  result = div (desc_len, buffer_data_size);
+  if (result.rem)
+    buffers_required = result.quot + 1;
+  else
+    buffers_required = result.quot;
+
+  return (buffers_required);
+}
+
+static_always_inline u32
+vhost_user_compute_indirect_desc_len (vhost_user_intf_t * vui,
+				      vhost_user_vring_t * txvq,
+				      u32 buffer_data_size, u16 desc_current,
+				      u32 * map_hint)
+{
+  vnet_virtio_vring_packed_desc_t *desc_table = txvq->packed_desc;
+  u32 desc_len = 0;
+  u16 desc_data_offset = vui->virtio_net_hdr_sz;
+  u16 desc_idx = desc_current;
+  u32 n_descs;
+
+  n_descs = desc_table[desc_idx].len >> 4;
+  desc_table = map_guest_mem (vui, desc_table[desc_idx].addr, map_hint);
+  if (PREDICT_FALSE (desc_table == 0))
+    return 0;
+
+  for (desc_idx = 0; desc_idx < n_descs; desc_idx++)
+    desc_len += desc_table[desc_idx].len;
+
+  if (PREDICT_TRUE (desc_len > desc_data_offset))
+    desc_len -= desc_data_offset;
+
+  return vhost_user_compute_buffers_required (desc_len, buffer_data_size);
+}
+
+static_always_inline u32
+vhost_user_compute_chained_desc_len (vhost_user_intf_t * vui,
+				     vhost_user_vring_t * txvq,
+				     u32 buffer_data_size, u16 * current,
+				     u16 * n_left)
+{
+  vnet_virtio_vring_packed_desc_t *desc_table = txvq->packed_desc;
+  u32 desc_len = 0;
+  u16 mask = txvq->qsz_mask;
+
+  while (desc_table[*current].flags & VRING_DESC_F_NEXT)
+    {
+      desc_len += desc_table[*current].len;
+      (*n_left)++;
+      *current = (*current + 1) & mask;
+      vhost_user_advance_last_avail_idx (txvq);
+    }
+  desc_len += desc_table[*current].len;
+  (*n_left)++;
+  *current = (*current + 1) & mask;
+  vhost_user_advance_last_avail_idx (txvq);
+
+  if (PREDICT_TRUE (desc_len > vui->virtio_net_hdr_sz))
+    desc_len -= vui->virtio_net_hdr_sz;
+
+  return vhost_user_compute_buffers_required (desc_len, buffer_data_size);
+}
+
+static_always_inline void
+vhost_user_assemble_packet (vnet_virtio_vring_packed_desc_t *desc_table,
+			    u16 *desc_idx, vlib_buffer_t *b_head,
+			    vlib_buffer_t **b_current, u32 **next,
+			    vlib_buffer_t ***b, u32 *bi_current,
+			    vhost_cpu_t *cpu, u16 *copy_len, u32 *buffers_used,
+			    u32 buffers_required, u32 *desc_data_offset,
+			    u32 buffer_data_size, u16 mask)
+{
+  u32 desc_data_l;
+
+  while (*desc_data_offset < desc_table[*desc_idx].len)
+    {
+      /* Get more output if necessary. Or end of packet. */
+      if (PREDICT_FALSE ((*b_current)->current_length == buffer_data_size))
+	{
+	  /* Get next output */
+	  u32 bi_next = **next;
+	  (*next)++;
+	  (*b_current)->next_buffer = bi_next;
+	  (*b_current)->flags |= VLIB_BUFFER_NEXT_PRESENT;
+	  *bi_current = bi_next;
+	  *b_current = **b;
+	  (*b)++;
+	  (*buffers_used)++;
+	  ASSERT (*buffers_used <= buffers_required);
+	}
+
+      /* Prepare a copy order executed later for the data */
+      ASSERT (*copy_len < VHOST_USER_COPY_ARRAY_N);
+      vhost_copy_t *cpy = &cpu->copy[*copy_len];
+      (*copy_len)++;
+      desc_data_l = desc_table[*desc_idx].len - *desc_data_offset;
+      cpy->len = buffer_data_size - (*b_current)->current_length;
+      cpy->len = (cpy->len > desc_data_l) ? desc_data_l : cpy->len;
+      cpy->dst = (uword) (vlib_buffer_get_current (*b_current) +
+			  (*b_current)->current_length);
+      cpy->src = desc_table[*desc_idx].addr + *desc_data_offset;
+
+      *desc_data_offset += cpy->len;
+
+      (*b_current)->current_length += cpy->len;
+      b_head->total_length_not_including_first_buffer += cpy->len;
+    }
+  *desc_idx = (*desc_idx + 1) & mask;;
+  *desc_data_offset = 0;
+}
+
+static_always_inline u32
+vhost_user_if_input_packed (vlib_main_t *vm, vhost_user_main_t *vum,
+			    vhost_user_intf_t *vui, u16 qid,
+			    vlib_node_runtime_t *node, u8 enable_csum)
+{
+  vhost_user_vring_t *txvq = &vui->vrings[VHOST_VRING_IDX_TX (qid)];
+  vnet_feature_main_t *fm = &feature_main;
+  u8 feature_arc_idx = fm->device_input_feature_arc_index;
+  u16 n_rx_packets = 0;
+  u32 n_rx_bytes = 0;
+  u16 n_left = 0;
+  u32 buffers_required = 0;
+  u32 n_left_to_next, *to_next;
+  u32 next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
+  u32 n_trace = vlib_get_trace_count (vm, node);
+  u32 buffer_data_size = vlib_buffer_get_default_data_size (vm);
+  u32 map_hint = 0;
+  vhost_cpu_t *cpu = &vum->cpus[vm->thread_index];
+  u16 copy_len = 0;
+  u32 current_config_index = ~0;
+  u16 mask = txvq->qsz_mask;
+  u16 desc_current, desc_head, last_used_idx;
+  vnet_virtio_vring_packed_desc_t *desc_table = 0;
+  u32 n_descs_processed = 0;
+  u32 rv;
+  vlib_buffer_t **b;
+  u32 *next;
+  u32 buffers_used = 0;
+  u16 current, n_descs_to_process;
+
+  /* The descriptor table is not ready yet */
+  if (PREDICT_FALSE (txvq->packed_desc == 0))
+    goto done;
+
+  /* do we have pending interrupts ? */
+  vhost_user_vring_t *rxvq = &vui->vrings[VHOST_VRING_IDX_RX (qid)];
+  vhost_user_input_do_interrupt (vm, vui, txvq, rxvq);
+
+  /*
+   * For adaptive mode, it is optimized to reduce interrupts.
+   * If the scheduler switches the input node to polling due
+   * to burst of traffic, we tell the driver no interrupt.
+   * When the traffic subsides, the scheduler switches the node back to
+   * interrupt mode. We must tell the driver we want interrupt.
+   */
+  if (PREDICT_FALSE (txvq->mode == VNET_HW_IF_RX_MODE_ADAPTIVE))
+    {
+      if ((node->flags &
+	   VLIB_NODE_FLAG_SWITCH_FROM_POLLING_TO_INTERRUPT_MODE) ||
+	  !(node->flags &
+	    VLIB_NODE_FLAG_SWITCH_FROM_INTERRUPT_TO_POLLING_MODE))
+	/* Tell driver we want notification */
+	txvq->used_event->flags = 0;
+      else
+	/* Tell driver we don't want notification */
+	txvq->used_event->flags = VRING_EVENT_F_DISABLE;
+    }
+
+  last_used_idx = txvq->last_used_idx & mask;
+  desc_head = desc_current = last_used_idx;
+
+  if (vhost_user_packed_desc_available (txvq, desc_current) == 0)
+    goto done;
+
+  if (PREDICT_FALSE (!vui->admin_up || !vui->is_ready || !(txvq->enabled)))
+    {
+      /*
+       * Discard input packet if interface is admin down or vring is not
+       * enabled.
+       * "For example, for a networking device, in the disabled state
+       * client must not supply any new RX packets, but must process
+       * and discard any TX packets."
+       */
+      rv = vhost_user_rx_discard_packet_packed (vm, vui, txvq,
+						VHOST_USER_DOWN_DISCARD_COUNT);
+      vlib_error_count (vm, vhost_user_input_node.index,
+			VHOST_USER_INPUT_FUNC_ERROR_NOT_READY, rv);
+      goto done;
+    }
+
+  vhost_user_input_setup_frame (vm, node, vui, &current_config_index,
+				&next_index, &to_next, &n_left_to_next);
+
+  /*
+   * Compute n_left and total buffers needed
+   */
+  desc_table = txvq->packed_desc;
+  current = desc_current;
+  while (vhost_user_packed_desc_available (txvq, current) &&
+	 (n_left < VLIB_FRAME_SIZE))
+    {
+      if (desc_table[current].flags & VRING_DESC_F_INDIRECT)
+	{
+	  buffers_required +=
+	    vhost_user_compute_indirect_desc_len (vui, txvq, buffer_data_size,
+						  current, &map_hint);
+	  n_left++;
+	  current = (current + 1) & mask;
+	  vhost_user_advance_last_avail_idx (txvq);
+	}
+      else
+	{
+	  buffers_required +=
+	    vhost_user_compute_chained_desc_len (vui, txvq, buffer_data_size,
+						 &current, &n_left);
+	}
+    }
+
+  /* Something is broken if we need more than 10000 buffers */
+  if (PREDICT_FALSE ((buffers_required == 0) || (buffers_required > 10000)))
+    {
+      rv = vhost_user_rx_discard_packet_packed (vm, vui, txvq, n_left);
+      vlib_error_count (vm, vhost_user_input_node.index,
+			VHOST_USER_INPUT_FUNC_ERROR_NO_BUFFER, rv);
+      goto done;
+    }
+
+  vec_validate (cpu->to_next_list, buffers_required);
+  rv = vlib_buffer_alloc (vm, cpu->to_next_list, buffers_required);
+  if (PREDICT_FALSE (rv != buffers_required))
+    {
+      vlib_buffer_free (vm, cpu->to_next_list, rv);
+      rv = vhost_user_rx_discard_packet_packed (vm, vui, txvq, n_left);
+      vlib_error_count (vm, vhost_user_input_node.index,
+			VHOST_USER_INPUT_FUNC_ERROR_NO_BUFFER, rv);
+      goto done;
+    }
+
+  next = cpu->to_next_list;
+  vec_validate (cpu->rx_buffers_pdesc, buffers_required);
+  vlib_get_buffers (vm, next, cpu->rx_buffers_pdesc, buffers_required);
+  b = cpu->rx_buffers_pdesc;
+  n_descs_processed = n_left;
+
+  while (n_left)
+    {
+      vlib_buffer_t *b_head, *b_current;
+      u32 bi_current;
+      u32 desc_data_offset;
+      u16 desc_idx = desc_current;
+      u32 n_descs;
+
+      desc_table = txvq->packed_desc;
+      to_next[0] = bi_current = next[0];
+      b_head = b_current = b[0];
+      b++;
+      buffers_used++;
+      ASSERT (buffers_used <= buffers_required);
+      to_next++;
+      next++;
+      n_left_to_next--;
+
+      /* The buffer should already be initialized */
+      b_head->total_length_not_including_first_buffer = 0;
+      b_head->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
+      desc_data_offset = vui->virtio_net_hdr_sz;
+      n_descs_to_process = 1;
+
+      if (desc_table[desc_idx].flags & VRING_DESC_F_INDIRECT)
+	{
+	  n_descs = desc_table[desc_idx].len >> 4;
+	  desc_table = map_guest_mem (vui, desc_table[desc_idx].addr,
+				      &map_hint);
+	  desc_idx = 0;
+	  if (PREDICT_FALSE (desc_table == 0) ||
+	      (enable_csum &&
+	       (PREDICT_FALSE
+		(vhost_user_do_offload
+		 (vui, desc_table, desc_idx, mask, b_head,
+		  &map_hint) != VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR))))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_INPUT_FUNC_ERROR_MMAP_FAIL, 1);
+	      to_next--;
+	      next--;
+	      n_left_to_next++;
+	      buffers_used--;
+	      b--;
+	      goto out;
+	    }
+	  while (n_descs)
+	    {
+	      vhost_user_assemble_packet (desc_table, &desc_idx, b_head,
+					  &b_current, &next, &b, &bi_current,
+					  cpu, &copy_len, &buffers_used,
+					  buffers_required, &desc_data_offset,
+					  buffer_data_size, mask);
+	      n_descs--;
+	    }
+	}
+      else
+	{
+	  if (enable_csum)
+	    {
+	      rv = vhost_user_do_offload (vui, desc_table, desc_idx, mask,
+					  b_head, &map_hint);
+	      if (PREDICT_FALSE (rv != VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR))
+		{
+		  vlib_error_count (vm, node->node_index, rv, 1);
+		  to_next--;
+		  next--;
+		  n_left_to_next++;
+		  buffers_used--;
+		  b--;
+		  goto out;
+		}
+	    }
+	  /*
+	   * For chained descriptor, we process all chains in a single while
+	   * loop. So count how many descriptors in the chain.
+	   */
+	  n_descs_to_process = 1;
+	  while (desc_table[desc_idx].flags & VRING_DESC_F_NEXT)
+	    {
+	      vhost_user_assemble_packet (desc_table, &desc_idx, b_head,
+					  &b_current, &next, &b, &bi_current,
+					  cpu, &copy_len, &buffers_used,
+					  buffers_required, &desc_data_offset,
+					  buffer_data_size, mask);
+	      n_descs_to_process++;
+	    }
+	  vhost_user_assemble_packet (desc_table, &desc_idx, b_head,
+				      &b_current, &next, &b, &bi_current,
+				      cpu, &copy_len, &buffers_used,
+				      buffers_required, &desc_data_offset,
+				      buffer_data_size, mask);
+	}
+
+      n_rx_bytes += b_head->total_length_not_including_first_buffer;
+      n_rx_packets++;
+
+      b_head->total_length_not_including_first_buffer -=
+	b_head->current_length;
+
+      vnet_buffer (b_head)->sw_if_index[VLIB_RX] = vui->sw_if_index;
+      vnet_buffer (b_head)->sw_if_index[VLIB_TX] = ~0;
+      b_head->error = 0;
+
+      if (current_config_index != ~0)
+	{
+	  b_head->current_config_index = current_config_index;
+	  vnet_buffer (b_head)->feature_arc_index = feature_arc_idx;
+	}
+
+    out:
+      ASSERT (n_left >= n_descs_to_process);
+      n_left -= n_descs_to_process;
+
+      /* advance to next descrptor */
+      desc_current = (desc_current + n_descs_to_process) & mask;
+
+      /*
+       * Although separating memory copies from virtio ring parsing
+       * is beneficial, we can offer to perform the copies from time
+       * to time in order to free some space in the ring.
+       */
+      if (PREDICT_FALSE (copy_len >= VHOST_USER_RX_COPY_THRESHOLD))
+	{
+	  rv = vhost_user_input_copy_packed (vui, cpu->copy, copy_len,
+					     &map_hint);
+	  if (PREDICT_FALSE (rv != VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR))
+	    vlib_error_count (vm, node->node_index, rv, 1);
+	  copy_len = 0;
+	}
+    }
+  vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+
+  /* Do the memory copies */
+  rv = vhost_user_input_copy_packed (vui, cpu->copy, copy_len, &map_hint);
+  if (PREDICT_FALSE (rv != VHOST_USER_INPUT_FUNC_ERROR_NO_ERROR))
+    vlib_error_count (vm, node->node_index, rv, 1);
+
+  /* Must do the tracing before giving buffers back to driver */
+  if (PREDICT_FALSE (n_trace))
+    {
+      u32 left = n_rx_packets;
+
+      b = cpu->rx_buffers_pdesc;
+      while (n_trace && left)
+	{
+	  if (PREDICT_TRUE
+	      (vlib_trace_buffer
+	       (vm, node, next_index, b[0], /* follow_chain */ 0)))
+	    {
+	      vhost_trace_t *t0;
+	      t0 = vlib_add_trace (vm, node, b[0], sizeof (t0[0]));
+	      vhost_user_rx_trace_packed (t0, vui, qid, txvq, last_used_idx);
+	      last_used_idx = (last_used_idx + 1) & mask;
+	      n_trace--;
+	      vlib_set_trace_count (vm, node, n_trace);
+	    }
+	  left--;
+	  b++;
+	}
+    }
+
+  /*
+   * Give buffers back to driver.
+   */
+  vhost_user_mark_desc_consumed (vui, txvq, desc_head, n_descs_processed);
+
+  /* interrupt (call) handling */
+  if ((txvq->callfd_idx != ~0) &&
+      (txvq->avail_event->flags != VRING_EVENT_F_DISABLE))
+    {
+      txvq->n_since_last_int += n_rx_packets;
+      if (txvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, vui, txvq);
+    }
+
+  /* increase rx counters */
+  vlib_increment_combined_counter
+    (vnet_main.interface_main.combined_sw_if_counters
+     + VNET_INTERFACE_COUNTER_RX, vm->thread_index, vui->sw_if_index,
+     n_rx_packets, n_rx_bytes);
+
+  vnet_device_increment_rx_packets (vm->thread_index, n_rx_packets);
+
+  if (PREDICT_FALSE (buffers_used < buffers_required))
+    vlib_buffer_free (vm, next, buffers_required - buffers_used);
+
+done:
+  return n_rx_packets;
+}
+
+VLIB_NODE_FN (vhost_user_input_node) (vlib_main_t * vm,
+				      vlib_node_runtime_t * node,
+				      vlib_frame_t * frame)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  uword n_rx_packets = 0;
+  vhost_user_intf_t *vui;
+  vnet_hw_if_rxq_poll_vector_t *pv = vnet_hw_if_get_rxq_poll_vector (vm, node);
+  vnet_hw_if_rxq_poll_vector_t *pve;
+
+  vec_foreach (pve, pv)
+    {
+      vui = pool_elt_at_index (vum->vhost_user_interfaces, pve->dev_instance);
+      if (vhost_user_is_packed_ring_supported (vui))
+	{
+	  if (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_CSUM))
+	    n_rx_packets += vhost_user_if_input_packed (
+	      vm, vum, vui, pve->queue_id, node, 1);
+	  else
+	    n_rx_packets += vhost_user_if_input_packed (
+	      vm, vum, vui, pve->queue_id, node, 0);
+	}
+      else
+	{
+	  if (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_CSUM))
+	    n_rx_packets +=
+	      vhost_user_if_input (vm, vum, vui, pve->queue_id, node, 1);
+	  else
+	    n_rx_packets +=
+	      vhost_user_if_input (vm, vum, vui, pve->queue_id, node, 0);
+	}
+    }
+
+  return n_rx_packets;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (vhost_user_input_node) = {
+  .type = VLIB_NODE_TYPE_INPUT,
+  .name = "vhost-user-input",
+  .sibling_of = "device-input",
+  .flags = VLIB_NODE_FLAG_TRACE_SUPPORTED,
+
+  /* Will be enabled if/when hardware is detected. */
+  .state = VLIB_NODE_STATE_DISABLED,
+
+  .format_buffer = format_ethernet_header_with_length,
+  .format_trace = format_vhost_trace,
+
+  .n_errors = VHOST_USER_INPUT_FUNC_N_ERROR,
+  .error_strings = vhost_user_input_func_error_strings,
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/vhost_user_output.c b/src/plugins/vhost/vhost_user_output.c
new file mode 100644
index 00000000000..9b52fc6265c
--- /dev/null
+++ b/src/plugins/vhost/vhost_user_output.c
@@ -0,0 +1,1145 @@
+/*
+ *------------------------------------------------------------------
+ * vhost-user-output
+ *
+ * Copyright (c) 2014-2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#include <stddef.h>
+#include <fcntl.h>		/* for open */
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/uio.h>		/* for iovec */
+#include <netinet/in.h>
+#include <sys/vfs.h>
+
+#include <linux/if_arp.h>
+#include <linux/if_tun.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/devices.h>
+#include <vnet/feature/feature.h>
+#include <vnet/ip/ip_psh_cksum.h>
+
+#include <vhost/vhost_user.h>
+#include <vhost/vhost_user_inline.h>
+
+#include <vnet/gso/hdr_offset_parser.h>
+/*
+ * On the transmit side, we keep processing the buffers from vlib in the while
+ * loop and prepare the copy order to be executed later. However, the static
+ * array which we keep the copy order is limited to VHOST_USER_COPY_ARRAY_N
+ * entries. In order to not corrupt memory, we have to do the copy when the
+ * static array reaches the copy threshold. We subtract 40 in case the code
+ * goes into the inner loop for a maximum of 64k frames which may require
+ * more array entries. We subtract 200 because our default buffer size is
+ * 2048 and the default desc len is likely 1536. While it takes less than 40
+ * vlib buffers for the jumbo frame, it may take twice as much descriptors
+ * for the same jumbo frame. Use 200 for the extra head room.
+ */
+#define VHOST_USER_TX_COPY_THRESHOLD (VHOST_USER_COPY_ARRAY_N - 200)
+
+extern vnet_device_class_t vhost_user_device_class;
+
+#define foreach_vhost_user_tx_func_error      \
+  _(NONE, "no error")  \
+  _(NOT_READY, "vhost vring not ready")  \
+  _(DOWN, "vhost interface is down")  \
+  _(PKT_DROP_NOBUF, "tx packet drops (no available descriptors)")  \
+  _(PKT_DROP_NOMRG, "tx packet drops (cannot merge descriptors)")  \
+  _(MMAP_FAIL, "mmap failure") \
+  _(INDIRECT_OVERFLOW, "indirect descriptor table overflow")
+
+typedef enum
+{
+#define _(f,s) VHOST_USER_TX_FUNC_ERROR_##f,
+  foreach_vhost_user_tx_func_error
+#undef _
+    VHOST_USER_TX_FUNC_N_ERROR,
+} vhost_user_tx_func_error_t;
+
+static __clib_unused char *vhost_user_tx_func_error_strings[] = {
+#define _(n,s) s,
+  foreach_vhost_user_tx_func_error
+#undef _
+};
+
+static __clib_unused u8 *
+format_vhost_user_interface_name (u8 * s, va_list * args)
+{
+  u32 i = va_arg (*args, u32);
+  u32 show_dev_instance = ~0;
+  vhost_user_main_t *vum = &vhost_user_main;
+
+  if (i < vec_len (vum->show_dev_instance_by_real_dev_instance))
+    show_dev_instance = vum->show_dev_instance_by_real_dev_instance[i];
+
+  if (show_dev_instance != ~0)
+    i = show_dev_instance;
+
+  s = format (s, "VirtualEthernet0/0/%d", i);
+  return s;
+}
+
+static __clib_unused int
+vhost_user_name_renumber (vnet_hw_interface_t * hi, u32 new_dev_instance)
+{
+  // FIXME: check if the new dev instance is already used
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui = pool_elt_at_index (vum->vhost_user_interfaces,
+					      hi->dev_instance);
+
+  vec_validate_init_empty (vum->show_dev_instance_by_real_dev_instance,
+			   hi->dev_instance, ~0);
+
+  vum->show_dev_instance_by_real_dev_instance[hi->dev_instance] =
+    new_dev_instance;
+
+  vu_log_debug (vui, "renumbered vhost-user interface dev_instance %d to %d",
+		hi->dev_instance, new_dev_instance);
+
+  return 0;
+}
+
+static_always_inline void
+vhost_user_tx_trace (vhost_trace_t * t,
+		     vhost_user_intf_t * vui, u16 qid,
+		     vlib_buffer_t * b, vhost_user_vring_t * rxvq)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u32 last_avail_idx = rxvq->last_avail_idx;
+  u32 desc_current = rxvq->avail->ring[last_avail_idx & rxvq->qsz_mask];
+  vnet_virtio_vring_desc_t *hdr_desc = 0;
+  u32 hint = 0;
+
+  clib_memset (t, 0, sizeof (*t));
+  t->device_index = vui - vum->vhost_user_interfaces;
+  t->qid = qid;
+
+  hdr_desc = &rxvq->desc[desc_current];
+  if (rxvq->desc[desc_current].flags & VRING_DESC_F_INDIRECT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_INDIRECT;
+      /* Header is the first here */
+      hdr_desc = map_guest_mem (vui, rxvq->desc[desc_current].addr, &hint);
+    }
+  if (rxvq->desc[desc_current].flags & VRING_DESC_F_NEXT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+    }
+  if (!(rxvq->desc[desc_current].flags & VRING_DESC_F_NEXT) &&
+      !(rxvq->desc[desc_current].flags & VRING_DESC_F_INDIRECT))
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SINGLE_DESC;
+    }
+
+  t->first_desc_len = hdr_desc ? hdr_desc->len : 0;
+}
+
+static_always_inline u32
+vhost_user_tx_copy (vhost_user_intf_t * vui, vhost_copy_t * cpy,
+		    u16 copy_len, u32 * map_hint)
+{
+  void *dst0, *dst1, *dst2, *dst3;
+  if (PREDICT_TRUE (copy_len >= 4))
+    {
+      if (PREDICT_FALSE (!(dst2 = map_guest_mem (vui, cpy[0].dst, map_hint))))
+	return 1;
+      if (PREDICT_FALSE (!(dst3 = map_guest_mem (vui, cpy[1].dst, map_hint))))
+	return 1;
+      while (PREDICT_TRUE (copy_len >= 4))
+	{
+	  dst0 = dst2;
+	  dst1 = dst3;
+
+	  if (PREDICT_FALSE
+	      (!(dst2 = map_guest_mem (vui, cpy[2].dst, map_hint))))
+	    return 1;
+	  if (PREDICT_FALSE
+	      (!(dst3 = map_guest_mem (vui, cpy[3].dst, map_hint))))
+	    return 1;
+
+	  clib_prefetch_load ((void *) cpy[2].src);
+	  clib_prefetch_load ((void *) cpy[3].src);
+
+	  clib_memcpy_fast (dst0, (void *) cpy[0].src, cpy[0].len);
+	  clib_memcpy_fast (dst1, (void *) cpy[1].src, cpy[1].len);
+
+	  vhost_user_log_dirty_pages_2 (vui, cpy[0].dst, cpy[0].len, 1);
+	  vhost_user_log_dirty_pages_2 (vui, cpy[1].dst, cpy[1].len, 1);
+	  copy_len -= 2;
+	  cpy += 2;
+	}
+    }
+  while (copy_len)
+    {
+      if (PREDICT_FALSE (!(dst0 = map_guest_mem (vui, cpy->dst, map_hint))))
+	return 1;
+      clib_memcpy_fast (dst0, (void *) cpy->src, cpy->len);
+      vhost_user_log_dirty_pages_2 (vui, cpy->dst, cpy->len, 1);
+      copy_len -= 1;
+      cpy += 1;
+    }
+  return 0;
+}
+
+static_always_inline void
+vhost_user_handle_tx_offload (vhost_user_intf_t *vui, vlib_buffer_t *b,
+			      vnet_virtio_net_hdr_t *hdr)
+{
+  generic_header_offset_t gho = { 0 };
+  int is_ip4 = b->flags & VNET_BUFFER_F_IS_IP4;
+  int is_ip6 = b->flags & VNET_BUFFER_F_IS_IP6;
+  vnet_buffer_oflags_t oflags = vnet_buffer (b)->oflags;
+  u16 psh_cksum = 0;
+  ip4_header_t *ip4 = 0;
+  ip6_header_t *ip6 = 0;
+
+  ASSERT (!(is_ip4 && is_ip6));
+  vnet_generic_header_offset_parser (b, &gho, 1 /* l2 */ , is_ip4, is_ip6);
+  if (oflags & VNET_BUFFER_OFFLOAD_F_IP_CKSUM)
+    {
+      ip4 =
+	(ip4_header_t *) (vlib_buffer_get_current (b) + gho.l3_hdr_offset);
+      ip4->checksum = ip4_header_checksum (ip4);
+      psh_cksum = ip4_pseudo_header_cksum (ip4);
+    }
+  else
+    {
+      ip6 = (ip6_header_t *) (vlib_buffer_get_current (b) + gho.l3_hdr_offset);
+      psh_cksum = ip6_pseudo_header_cksum (ip6);
+    }
+
+  /* checksum offload */
+  if (oflags & VNET_BUFFER_OFFLOAD_F_UDP_CKSUM)
+    {
+      udp_header_t *udp =
+	(udp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
+      udp->checksum = psh_cksum;
+      hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+      hdr->csum_start = gho.l4_hdr_offset;
+      hdr->csum_offset = offsetof (udp_header_t, checksum);
+    }
+  else if (oflags & VNET_BUFFER_OFFLOAD_F_TCP_CKSUM)
+    {
+      tcp_header_t *tcp =
+	(tcp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
+      tcp->checksum = psh_cksum;
+      hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+      hdr->csum_start = gho.l4_hdr_offset;
+      hdr->csum_offset = offsetof (tcp_header_t, checksum);
+    }
+
+  /* GSO offload */
+  if (b->flags & VNET_BUFFER_F_GSO)
+    {
+      if (oflags & VNET_BUFFER_OFFLOAD_F_TCP_CKSUM)
+	{
+	  if (is_ip4 &&
+	      (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_TSO4)))
+	    {
+	      hdr->gso_size = vnet_buffer2 (b)->gso_size;
+	      hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+	    }
+	  else if (is_ip6 &&
+		   (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_TSO6)))
+	    {
+	      hdr->gso_size = vnet_buffer2 (b)->gso_size;
+	      hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+	    }
+	}
+      else if ((vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_UFO)) &&
+	       (oflags & VNET_BUFFER_OFFLOAD_F_UDP_CKSUM))
+	{
+	  hdr->gso_size = vnet_buffer2 (b)->gso_size;
+	  hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
+	}
+    }
+}
+
+static_always_inline void
+vhost_user_mark_desc_available (vlib_main_t * vm, vhost_user_intf_t * vui,
+				vhost_user_vring_t * rxvq,
+				u16 * n_descs_processed, u8 chained,
+				vlib_frame_t * frame, u32 n_left)
+{
+  u16 desc_idx, flags;
+  vnet_virtio_vring_packed_desc_t *desc_table = rxvq->packed_desc;
+  u16 last_used_idx = rxvq->last_used_idx;
+
+  if (PREDICT_FALSE (*n_descs_processed == 0))
+    return;
+
+  if (rxvq->used_wrap_counter)
+    flags = desc_table[last_used_idx & rxvq->qsz_mask].flags |
+      (VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+  else
+    flags = desc_table[last_used_idx & rxvq->qsz_mask].flags &
+      ~(VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+
+  vhost_user_advance_last_used_idx (rxvq);
+
+  for (desc_idx = 1; desc_idx < *n_descs_processed; desc_idx++)
+    {
+      if (rxvq->used_wrap_counter)
+	desc_table[rxvq->last_used_idx & rxvq->qsz_mask].flags |=
+	  (VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+      else
+	desc_table[rxvq->last_used_idx & rxvq->qsz_mask].flags &=
+	  ~(VRING_DESC_F_AVAIL | VRING_DESC_F_USED);
+      vhost_user_advance_last_used_idx (rxvq);
+    }
+
+  desc_table[last_used_idx & rxvq->qsz_mask].flags = flags;
+
+  *n_descs_processed = 0;
+
+  if (chained)
+    {
+      vnet_virtio_vring_packed_desc_t *desc_table = rxvq->packed_desc;
+
+      while (desc_table[rxvq->last_used_idx & rxvq->qsz_mask].flags &
+	     VRING_DESC_F_NEXT)
+	vhost_user_advance_last_used_idx (rxvq);
+
+      /* Advance past the current chained table entries */
+      vhost_user_advance_last_used_idx (rxvq);
+    }
+
+  /* interrupt (call) handling */
+  if ((rxvq->callfd_idx != ~0) &&
+      (rxvq->avail_event->flags != VRING_EVENT_F_DISABLE))
+    {
+      vhost_user_main_t *vum = &vhost_user_main;
+
+      rxvq->n_since_last_int += frame->n_vectors - n_left;
+      if (rxvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, vui, rxvq);
+    }
+}
+
+static_always_inline void
+vhost_user_tx_trace_packed (vhost_trace_t * t, vhost_user_intf_t * vui,
+			    u16 qid, vlib_buffer_t * b,
+			    vhost_user_vring_t * rxvq)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u32 last_avail_idx = rxvq->last_avail_idx;
+  u32 desc_current = last_avail_idx & rxvq->qsz_mask;
+  vnet_virtio_vring_packed_desc_t *hdr_desc = 0;
+  u32 hint = 0;
+
+  clib_memset (t, 0, sizeof (*t));
+  t->device_index = vui - vum->vhost_user_interfaces;
+  t->qid = qid;
+
+  hdr_desc = &rxvq->packed_desc[desc_current];
+  if (rxvq->packed_desc[desc_current].flags & VRING_DESC_F_INDIRECT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_INDIRECT;
+      /* Header is the first here */
+      hdr_desc = map_guest_mem (vui, rxvq->packed_desc[desc_current].addr,
+				&hint);
+    }
+  if (rxvq->packed_desc[desc_current].flags & VRING_DESC_F_NEXT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+    }
+  if (!(rxvq->packed_desc[desc_current].flags & VRING_DESC_F_NEXT) &&
+      !(rxvq->packed_desc[desc_current].flags & VRING_DESC_F_INDIRECT))
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SINGLE_DESC;
+    }
+
+  t->first_desc_len = hdr_desc ? hdr_desc->len : 0;
+}
+
+static_always_inline uword
+vhost_user_device_class_packed (vlib_main_t *vm, vlib_node_runtime_t *node,
+				vlib_frame_t *frame, vhost_user_intf_t *vui,
+				vhost_user_vring_t *rxvq)
+{
+  u32 *buffers = vlib_frame_vector_args (frame);
+  u32 n_left = frame->n_vectors;
+  vhost_user_main_t *vum = &vhost_user_main;
+  u32 qid = rxvq->qid;
+  u8 error;
+  u32 thread_index = vm->thread_index;
+  vhost_cpu_t *cpu = &vum->cpus[thread_index];
+  u32 map_hint = 0;
+  u8 retry = 8;
+  u16 copy_len;
+  u16 tx_headers_len;
+  vnet_virtio_vring_packed_desc_t *desc_table;
+  u32 or_flags;
+  u16 desc_head, desc_index, desc_len;
+  u16 n_descs_processed;
+  u8 indirect, chained;
+
+retry:
+  error = VHOST_USER_TX_FUNC_ERROR_NONE;
+  tx_headers_len = 0;
+  copy_len = 0;
+  n_descs_processed = 0;
+
+  while (n_left > 0)
+    {
+      vlib_buffer_t *b0, *current_b0;
+      uword buffer_map_addr;
+      u32 buffer_len;
+      u16 bytes_left;
+      u32 total_desc_len = 0;
+      u16 n_entries = 0;
+
+      indirect = 0;
+      chained = 0;
+      if (PREDICT_TRUE (n_left > 1))
+	vlib_prefetch_buffer_with_index (vm, buffers[1], LOAD);
+
+      b0 = vlib_get_buffer (vm, buffers[0]);
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  cpu->current_trace = vlib_add_trace (vm, node, b0,
+					       sizeof (*cpu->current_trace));
+	  vhost_user_tx_trace_packed (cpu->current_trace, vui, qid / 2, b0,
+				      rxvq);
+	}
+
+      desc_table = rxvq->packed_desc;
+      desc_head = desc_index = rxvq->last_avail_idx & rxvq->qsz_mask;
+      if (PREDICT_FALSE (!vhost_user_packed_desc_available (rxvq, desc_head)))
+	{
+	  error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF;
+	  goto done;
+	}
+      /*
+       * Go deeper in case of indirect descriptor.
+       * To test it, turn off mrg_rxbuf.
+       */
+      if (desc_table[desc_head].flags & VRING_DESC_F_INDIRECT)
+	{
+	  indirect = 1;
+	  if (PREDICT_FALSE (desc_table[desc_head].len <
+			     sizeof (vnet_virtio_vring_packed_desc_t)))
+	    {
+	      error = VHOST_USER_TX_FUNC_ERROR_INDIRECT_OVERFLOW;
+	      goto done;
+	    }
+	  n_entries = desc_table[desc_head].len >> 4;
+	  desc_table = map_guest_mem (vui, desc_table[desc_index].addr,
+				      &map_hint);
+	  if (PREDICT_FALSE (desc_table == 0))
+	    {
+	      error = VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL;
+	      goto done;
+	    }
+	  desc_index = 0;
+	}
+      else if (rxvq->packed_desc[desc_head].flags & VRING_DESC_F_NEXT)
+	chained = 1;
+
+      desc_len = vui->virtio_net_hdr_sz;
+      buffer_map_addr = desc_table[desc_index].addr;
+      buffer_len = desc_table[desc_index].len;
+
+      /* Get a header from the header array */
+      vnet_virtio_net_hdr_mrg_rxbuf_t *hdr = &cpu->tx_headers[tx_headers_len];
+      tx_headers_len++;
+      hdr->hdr.flags = 0;
+      hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+      hdr->num_buffers = 1;
+
+      or_flags = (b0->flags & VNET_BUFFER_F_OFFLOAD);
+
+      /* Guest supports csum offload and buffer requires checksum offload? */
+      if (or_flags &&
+	  (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_CSUM)))
+	vhost_user_handle_tx_offload (vui, b0, &hdr->hdr);
+
+      /* Prepare a copy order executed later for the header */
+      ASSERT (copy_len < VHOST_USER_COPY_ARRAY_N);
+      vhost_copy_t *cpy = &cpu->copy[copy_len];
+      copy_len++;
+      cpy->len = vui->virtio_net_hdr_sz;
+      cpy->dst = buffer_map_addr;
+      cpy->src = (uword) hdr;
+
+      buffer_map_addr += vui->virtio_net_hdr_sz;
+      buffer_len -= vui->virtio_net_hdr_sz;
+      bytes_left = b0->current_length;
+      current_b0 = b0;
+      while (1)
+	{
+	  if (buffer_len == 0)
+	    {
+	      /* Get new output */
+	      if (chained)
+		{
+		  /*
+		   * Next one is chained
+		   * Test it with both indirect and mrg_rxbuf off
+		   */
+		  if (PREDICT_FALSE (!(desc_table[desc_index].flags &
+				       VRING_DESC_F_NEXT)))
+		    {
+		      /*
+		       * Last descriptor in chain.
+		       * Dequeue queued descriptors for this packet
+		       */
+		      vhost_user_dequeue_chained_descs (rxvq,
+							&n_descs_processed);
+		      error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF;
+		      goto done;
+		    }
+		  vhost_user_advance_last_avail_idx (rxvq);
+		  desc_index = rxvq->last_avail_idx & rxvq->qsz_mask;
+		  n_descs_processed++;
+		  buffer_map_addr = desc_table[desc_index].addr;
+		  buffer_len = desc_table[desc_index].len;
+		  total_desc_len += desc_len;
+		  desc_len = 0;
+		}
+	      else if (indirect)
+		{
+		  /*
+		   * Indirect table
+		   * Test it with mrg_rxnuf off
+		   */
+		  if (PREDICT_TRUE (n_entries > 0))
+		    n_entries--;
+		  else
+		    {
+		      /* Dequeue queued descriptors for this packet */
+		      vhost_user_dequeue_chained_descs (rxvq,
+							&n_descs_processed);
+		      error = VHOST_USER_TX_FUNC_ERROR_INDIRECT_OVERFLOW;
+		      goto done;
+		    }
+		  total_desc_len += desc_len;
+		  desc_index = (desc_index + 1) & rxvq->qsz_mask;
+		  buffer_map_addr = desc_table[desc_index].addr;
+		  buffer_len = desc_table[desc_index].len;
+		  desc_len = 0;
+		}
+	      else if (vui->virtio_net_hdr_sz == 12)
+		{
+		  /*
+		   * MRG is available
+		   * This is the default setting for the guest VM
+		   */
+		  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr =
+		    &cpu->tx_headers[tx_headers_len - 1];
+
+		  desc_table[desc_index].len = desc_len;
+		  vhost_user_advance_last_avail_idx (rxvq);
+		  desc_head = desc_index =
+		    rxvq->last_avail_idx & rxvq->qsz_mask;
+		  hdr->num_buffers++;
+		  n_descs_processed++;
+		  desc_len = 0;
+
+		  if (PREDICT_FALSE (!vhost_user_packed_desc_available
+				     (rxvq, desc_index)))
+		    {
+		      /* Dequeue queued descriptors for this packet */
+		      vhost_user_dequeue_descs (rxvq, hdr,
+						&n_descs_processed);
+		      error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF;
+		      goto done;
+		    }
+
+		  buffer_map_addr = desc_table[desc_index].addr;
+		  buffer_len = desc_table[desc_index].len;
+		}
+	      else
+		{
+		  error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOMRG;
+		  goto done;
+		}
+	    }
+
+	  ASSERT (copy_len < VHOST_USER_COPY_ARRAY_N);
+	  vhost_copy_t *cpy = &cpu->copy[copy_len];
+	  copy_len++;
+	  cpy->len = bytes_left;
+	  cpy->len = (cpy->len > buffer_len) ? buffer_len : cpy->len;
+	  cpy->dst = buffer_map_addr;
+	  cpy->src = (uword) vlib_buffer_get_current (current_b0) +
+	    current_b0->current_length - bytes_left;
+
+	  bytes_left -= cpy->len;
+	  buffer_len -= cpy->len;
+	  buffer_map_addr += cpy->len;
+	  desc_len += cpy->len;
+
+	  clib_prefetch_load (&rxvq->packed_desc);
+
+	  /* Check if vlib buffer has more data. If not, get more or break */
+	  if (PREDICT_TRUE (!bytes_left))
+	    {
+	      if (PREDICT_FALSE
+		  (current_b0->flags & VLIB_BUFFER_NEXT_PRESENT))
+		{
+		  current_b0 = vlib_get_buffer (vm, current_b0->next_buffer);
+		  bytes_left = current_b0->current_length;
+		}
+	      else
+		{
+		  /* End of packet */
+		  break;
+		}
+	    }
+	}
+
+      /* Move from available to used ring */
+      total_desc_len += desc_len;
+      rxvq->packed_desc[desc_head].len = total_desc_len;
+
+      vhost_user_advance_last_avail_table_idx (vui, rxvq, chained);
+      n_descs_processed++;
+
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+	cpu->current_trace->hdr = cpu->tx_headers[tx_headers_len - 1];
+
+      n_left--;
+
+      /*
+       * Do the copy periodically to prevent
+       * cpu->copy array overflow and corrupt memory
+       */
+      if (PREDICT_FALSE (copy_len >= VHOST_USER_TX_COPY_THRESHOLD) || chained)
+	{
+	  if (PREDICT_FALSE (vhost_user_tx_copy (vui, cpu->copy, copy_len,
+						 &map_hint)))
+	    vlib_error_count (vm, node->node_index,
+			      VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL, 1);
+	  copy_len = 0;
+
+	  /* give buffers back to driver */
+	  vhost_user_mark_desc_available (vm, vui, rxvq, &n_descs_processed,
+					  chained, frame, n_left);
+	}
+
+      buffers++;
+    }
+
+done:
+  if (PREDICT_TRUE (copy_len))
+    {
+      if (PREDICT_FALSE (vhost_user_tx_copy (vui, cpu->copy, copy_len,
+					     &map_hint)))
+	vlib_error_count (vm, node->node_index,
+			  VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL, 1);
+
+      vhost_user_mark_desc_available (vm, vui, rxvq, &n_descs_processed,
+				      chained, frame, n_left);
+    }
+
+  /*
+   * When n_left is set, error is always set to something too.
+   * In case error is due to lack of remaining buffers, we go back up and
+   * retry.
+   * The idea is that it is better to waste some time on packets
+   * that have been processed already than dropping them and get
+   * more fresh packets with a good likelyhood that they will be dropped too.
+   * This technique also gives more time to VM driver to pick-up packets.
+   * In case the traffic flows from physical to virtual interfaces, this
+   * technique will end-up leveraging the physical NIC buffer in order to
+   * absorb the VM's CPU jitter.
+   */
+  if (n_left && (error == VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF) && retry)
+    {
+      retry--;
+      goto retry;
+    }
+
+  clib_spinlock_unlock (&rxvq->vring_lock);
+
+  if (PREDICT_FALSE (n_left && error != VHOST_USER_TX_FUNC_ERROR_NONE))
+    {
+      vlib_error_count (vm, node->node_index, error, n_left);
+      vlib_increment_simple_counter
+	(vnet_main.interface_main.sw_if_counters +
+	 VNET_INTERFACE_COUNTER_DROP, thread_index, vui->sw_if_index, n_left);
+    }
+
+  vlib_buffer_free (vm, vlib_frame_vector_args (frame), frame->n_vectors);
+  return frame->n_vectors;
+}
+
+VNET_DEVICE_CLASS_TX_FN (vhost_user_device_class) (vlib_main_t * vm,
+						   vlib_node_runtime_t *
+						   node, vlib_frame_t * frame)
+{
+  u32 *buffers = vlib_frame_vector_args (frame);
+  u32 n_left = frame->n_vectors;
+  vhost_user_main_t *vum = &vhost_user_main;
+  vnet_interface_output_runtime_t *rd = (void *) node->runtime_data;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, rd->dev_instance);
+  u32 qid;
+  vhost_user_vring_t *rxvq;
+  u8 error;
+  u32 thread_index = vm->thread_index;
+  vhost_cpu_t *cpu = &vum->cpus[thread_index];
+  u32 map_hint = 0;
+  u8 retry = 8;
+  u16 copy_len;
+  u16 tx_headers_len;
+  u32 or_flags;
+  vnet_hw_if_tx_frame_t *tf = vlib_frame_scalar_args (frame);
+
+  if (PREDICT_FALSE (!vui->admin_up))
+    {
+      error = VHOST_USER_TX_FUNC_ERROR_DOWN;
+      goto done3;
+    }
+
+  if (PREDICT_FALSE (!vui->is_ready))
+    {
+      error = VHOST_USER_TX_FUNC_ERROR_NOT_READY;
+      goto done3;
+    }
+
+  qid = VHOST_VRING_IDX_RX (tf->queue_id);
+  rxvq = &vui->vrings[qid];
+  ASSERT (tf->queue_id == rxvq->qid);
+
+  if (PREDICT_FALSE (rxvq->avail == 0))
+    {
+      error = VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL;
+      goto done3;
+    }
+  if (tf->shared_queue)
+    clib_spinlock_lock (&rxvq->vring_lock);
+
+  if (vhost_user_is_packed_ring_supported (vui))
+    return (vhost_user_device_class_packed (vm, node, frame, vui, rxvq));
+
+retry:
+  error = VHOST_USER_TX_FUNC_ERROR_NONE;
+  tx_headers_len = 0;
+  copy_len = 0;
+  while (n_left > 0)
+    {
+      vlib_buffer_t *b0, *current_b0;
+      u16 desc_head, desc_index, desc_len;
+      vnet_virtio_vring_desc_t *desc_table;
+      uword buffer_map_addr;
+      u32 buffer_len;
+      u16 bytes_left;
+
+      if (PREDICT_TRUE (n_left > 1))
+	vlib_prefetch_buffer_with_index (vm, buffers[1], LOAD);
+
+      b0 = vlib_get_buffer (vm, buffers[0]);
+
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  cpu->current_trace = vlib_add_trace (vm, node, b0,
+					       sizeof (*cpu->current_trace));
+	  vhost_user_tx_trace (cpu->current_trace, vui, qid / 2, b0, rxvq);
+	}
+
+      if (PREDICT_FALSE (rxvq->last_avail_idx == rxvq->avail->idx))
+	{
+	  error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF;
+	  goto done;
+	}
+
+      desc_table = rxvq->desc;
+      desc_head = desc_index =
+	rxvq->avail->ring[rxvq->last_avail_idx & rxvq->qsz_mask];
+
+      /* Go deeper in case of indirect descriptor
+       * I don't know of any driver providing indirect for RX. */
+      if (PREDICT_FALSE (rxvq->desc[desc_head].flags & VRING_DESC_F_INDIRECT))
+	{
+	  if (PREDICT_FALSE (rxvq->desc[desc_head].len <
+			     sizeof (vnet_virtio_vring_desc_t)))
+	    {
+	      error = VHOST_USER_TX_FUNC_ERROR_INDIRECT_OVERFLOW;
+	      goto done;
+	    }
+	  if (PREDICT_FALSE
+	      (!(desc_table =
+		 map_guest_mem (vui, rxvq->desc[desc_index].addr,
+				&map_hint))))
+	    {
+	      error = VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL;
+	      goto done;
+	    }
+	  desc_index = 0;
+	}
+
+      desc_len = vui->virtio_net_hdr_sz;
+      buffer_map_addr = desc_table[desc_index].addr;
+      buffer_len = desc_table[desc_index].len;
+
+      {
+	// Get a header from the header array
+	vnet_virtio_net_hdr_mrg_rxbuf_t *hdr =
+	  &cpu->tx_headers[tx_headers_len];
+	tx_headers_len++;
+	hdr->hdr.flags = 0;
+	hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+	hdr->num_buffers = 1;	//This is local, no need to check
+
+	or_flags = (b0->flags & VNET_BUFFER_F_OFFLOAD);
+
+	/* Guest supports csum offload and buffer requires checksum offload? */
+	if (or_flags
+	    && (vui->features & VIRTIO_FEATURE (VIRTIO_NET_F_GUEST_CSUM)))
+	  vhost_user_handle_tx_offload (vui, b0, &hdr->hdr);
+
+	// Prepare a copy order executed later for the header
+	ASSERT (copy_len < VHOST_USER_COPY_ARRAY_N);
+	vhost_copy_t *cpy = &cpu->copy[copy_len];
+	copy_len++;
+	cpy->len = vui->virtio_net_hdr_sz;
+	cpy->dst = buffer_map_addr;
+	cpy->src = (uword) hdr;
+      }
+
+      buffer_map_addr += vui->virtio_net_hdr_sz;
+      buffer_len -= vui->virtio_net_hdr_sz;
+      bytes_left = b0->current_length;
+      current_b0 = b0;
+      while (1)
+	{
+	  if (buffer_len == 0)
+	    {			//Get new output
+	      if (desc_table[desc_index].flags & VRING_DESC_F_NEXT)
+		{
+		  //Next one is chained
+		  desc_index = desc_table[desc_index].next;
+		  buffer_map_addr = desc_table[desc_index].addr;
+		  buffer_len = desc_table[desc_index].len;
+		}
+	      else if (vui->virtio_net_hdr_sz == 12)	//MRG is available
+		{
+		  vnet_virtio_net_hdr_mrg_rxbuf_t *hdr =
+		    &cpu->tx_headers[tx_headers_len - 1];
+
+		  //Move from available to used buffer
+		  rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].id =
+		    desc_head;
+		  rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].len =
+		    desc_len;
+		  vhost_user_log_dirty_ring (vui, rxvq,
+					     ring[rxvq->last_used_idx &
+						  rxvq->qsz_mask]);
+
+		  rxvq->last_avail_idx++;
+		  rxvq->last_used_idx++;
+		  hdr->num_buffers++;
+		  desc_len = 0;
+
+		  if (PREDICT_FALSE
+		      (rxvq->last_avail_idx == rxvq->avail->idx))
+		    {
+		      //Dequeue queued descriptors for this packet
+		      rxvq->last_used_idx -= hdr->num_buffers - 1;
+		      rxvq->last_avail_idx -= hdr->num_buffers - 1;
+		      error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF;
+		      goto done;
+		    }
+
+		  desc_table = rxvq->desc;
+		  desc_head = desc_index =
+		    rxvq->avail->ring[rxvq->last_avail_idx & rxvq->qsz_mask];
+		  if (PREDICT_FALSE
+		      (rxvq->desc[desc_head].flags & VRING_DESC_F_INDIRECT))
+		    {
+		      //It is seriously unlikely that a driver will put indirect descriptor
+		      //after non-indirect descriptor.
+		      if (PREDICT_FALSE (rxvq->desc[desc_head].len <
+					 sizeof (vnet_virtio_vring_desc_t)))
+			{
+			  error = VHOST_USER_TX_FUNC_ERROR_INDIRECT_OVERFLOW;
+			  goto done;
+			}
+		      if (PREDICT_FALSE
+			  (!(desc_table =
+			     map_guest_mem (vui,
+					    rxvq->desc[desc_index].addr,
+					    &map_hint))))
+			{
+			  error = VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL;
+			  goto done;
+			}
+		      desc_index = 0;
+		    }
+		  buffer_map_addr = desc_table[desc_index].addr;
+		  buffer_len = desc_table[desc_index].len;
+		}
+	      else
+		{
+		  error = VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOMRG;
+		  goto done;
+		}
+	    }
+
+	  {
+	    ASSERT (copy_len < VHOST_USER_COPY_ARRAY_N);
+	    vhost_copy_t *cpy = &cpu->copy[copy_len];
+	    copy_len++;
+	    cpy->len = bytes_left;
+	    cpy->len = (cpy->len > buffer_len) ? buffer_len : cpy->len;
+	    cpy->dst = buffer_map_addr;
+	    cpy->src = (uword) vlib_buffer_get_current (current_b0) +
+	      current_b0->current_length - bytes_left;
+
+	    bytes_left -= cpy->len;
+	    buffer_len -= cpy->len;
+	    buffer_map_addr += cpy->len;
+	    desc_len += cpy->len;
+
+	    clib_prefetch_load (&rxvq->desc);
+	  }
+
+	  // Check if vlib buffer has more data. If not, get more or break.
+	  if (PREDICT_TRUE (!bytes_left))
+	    {
+	      if (PREDICT_FALSE
+		  (current_b0->flags & VLIB_BUFFER_NEXT_PRESENT))
+		{
+		  current_b0 = vlib_get_buffer (vm, current_b0->next_buffer);
+		  bytes_left = current_b0->current_length;
+		}
+	      else
+		{
+		  //End of packet
+		  break;
+		}
+	    }
+	}
+
+      //Move from available to used ring
+      rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].id = desc_head;
+      rxvq->used->ring[rxvq->last_used_idx & rxvq->qsz_mask].len = desc_len;
+      vhost_user_log_dirty_ring (vui, rxvq,
+				 ring[rxvq->last_used_idx & rxvq->qsz_mask]);
+      rxvq->last_avail_idx++;
+      rxvq->last_used_idx++;
+
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  cpu->current_trace->hdr = cpu->tx_headers[tx_headers_len - 1];
+	}
+
+      n_left--;			//At the end for error counting when 'goto done' is invoked
+
+      /*
+       * Do the copy periodically to prevent
+       * cpu->copy array overflow and corrupt memory
+       */
+      if (PREDICT_FALSE (copy_len >= VHOST_USER_TX_COPY_THRESHOLD))
+	{
+	  if (PREDICT_FALSE (vhost_user_tx_copy (vui, cpu->copy, copy_len,
+						 &map_hint)))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL, 1);
+	    }
+	  copy_len = 0;
+
+	  /* give buffers back to driver */
+	  CLIB_MEMORY_BARRIER ();
+	  rxvq->used->idx = rxvq->last_used_idx;
+	  vhost_user_log_dirty_ring (vui, rxvq, idx);
+	}
+      buffers++;
+    }
+
+done:
+  //Do the memory copies
+  if (PREDICT_FALSE (vhost_user_tx_copy (vui, cpu->copy, copy_len,
+					 &map_hint)))
+    {
+      vlib_error_count (vm, node->node_index,
+			VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL, 1);
+    }
+
+  CLIB_MEMORY_BARRIER ();
+  rxvq->used->idx = rxvq->last_used_idx;
+  vhost_user_log_dirty_ring (vui, rxvq, idx);
+
+  /*
+   * When n_left is set, error is always set to something too.
+   * In case error is due to lack of remaining buffers, we go back up and
+   * retry.
+   * The idea is that it is better to waste some time on packets
+   * that have been processed already than dropping them and get
+   * more fresh packets with a good likelihood that they will be dropped too.
+   * This technique also gives more time to VM driver to pick-up packets.
+   * In case the traffic flows from physical to virtual interfaces, this
+   * technique will end-up leveraging the physical NIC buffer in order to
+   * absorb the VM's CPU jitter.
+   */
+  if (n_left && (error == VHOST_USER_TX_FUNC_ERROR_PKT_DROP_NOBUF) && retry)
+    {
+      retry--;
+      goto retry;
+    }
+
+  /* interrupt (call) handling */
+  if ((rxvq->callfd_idx != ~0) &&
+      !(rxvq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+    {
+      rxvq->n_since_last_int += frame->n_vectors - n_left;
+
+      if (rxvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, vui, rxvq);
+    }
+
+  clib_spinlock_unlock (&rxvq->vring_lock);
+
+done3:
+  if (PREDICT_FALSE (n_left && error != VHOST_USER_TX_FUNC_ERROR_NONE))
+    {
+      vlib_error_count (vm, node->node_index, error, n_left);
+      vlib_increment_simple_counter
+	(vnet_main.interface_main.sw_if_counters
+	 + VNET_INTERFACE_COUNTER_DROP,
+	 thread_index, vui->sw_if_index, n_left);
+    }
+
+  vlib_buffer_free (vm, vlib_frame_vector_args (frame), frame->n_vectors);
+  return frame->n_vectors;
+}
+
+static __clib_unused clib_error_t *
+vhost_user_interface_rx_mode_change (vnet_main_t * vnm, u32 hw_if_index,
+				     u32 qid, vnet_hw_if_rx_mode mode)
+{
+  vlib_main_t *vm = vnm->vlib_main;
+  vnet_hw_interface_t *hif = vnet_get_hw_interface (vnm, hw_if_index);
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, hif->dev_instance);
+  vhost_user_vring_t *txvq = &vui->vrings[VHOST_VRING_IDX_TX (qid)];
+  vhost_cpu_t *cpu;
+
+  if (mode == txvq->mode)
+    return 0;
+
+  if ((mode != VNET_HW_IF_RX_MODE_POLLING) &&
+      (mode != VNET_HW_IF_RX_MODE_ADAPTIVE) &&
+      (mode != VNET_HW_IF_RX_MODE_INTERRUPT))
+    {
+      vu_log_err (vui, "unhandled mode %d changed for if %d queue %d", mode,
+		  hw_if_index, qid);
+      return clib_error_return (0, "unsupported");
+    }
+
+  if (txvq->thread_index == ~0)
+    return clib_error_return (0, "Queue initialization is not finished yet");
+
+  cpu = vec_elt_at_index (vum->cpus, txvq->thread_index);
+  if ((mode == VNET_HW_IF_RX_MODE_INTERRUPT) ||
+      (mode == VNET_HW_IF_RX_MODE_ADAPTIVE))
+    {
+      if (txvq->kickfd_idx == ~0)
+	{
+	  // We cannot support interrupt mode if the driver opts out
+	  return clib_error_return (0, "Driver does not support interrupt");
+	}
+      if (txvq->mode == VNET_HW_IF_RX_MODE_POLLING)
+	{
+	  ASSERT (cpu->polling_q_count != 0);
+	  if (cpu->polling_q_count)
+	    cpu->polling_q_count--;
+	  vum->ifq_count++;
+	  // Start the timer if this is the first encounter on interrupt
+	  // interface/queue
+	  if ((vum->ifq_count == 1) &&
+	      ((vum->coalesce_time > 0.0) || (vum->coalesce_frames > 0)))
+	    vlib_process_signal_event (vm,
+				       vhost_user_send_interrupt_node.index,
+				       VHOST_USER_EVENT_START_TIMER, 0);
+	}
+    }
+  else if (mode == VNET_HW_IF_RX_MODE_POLLING)
+    {
+      if (((txvq->mode == VNET_HW_IF_RX_MODE_INTERRUPT) ||
+	   (txvq->mode == VNET_HW_IF_RX_MODE_ADAPTIVE)) && vum->ifq_count)
+	{
+	  cpu->polling_q_count++;
+	  vum->ifq_count--;
+	  // Stop the timer if there is no more interrupt interface/queue
+	  if (vum->ifq_count == 0)
+	    vlib_process_signal_event (vm,
+				       vhost_user_send_interrupt_node.index,
+				       VHOST_USER_EVENT_STOP_TIMER, 0);
+	}
+    }
+
+  txvq->mode = mode;
+  vhost_user_set_operation_mode (vui, txvq);
+
+  return 0;
+}
+
+static __clib_unused clib_error_t *
+vhost_user_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index,
+				    u32 flags)
+{
+  vnet_hw_interface_t *hif = vnet_get_hw_interface (vnm, hw_if_index);
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, hif->dev_instance);
+  u8 link_old, link_new;
+
+  link_old = vui_is_link_up (vui);
+
+  vui->admin_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
+
+  link_new = vui_is_link_up (vui);
+
+  if (link_old != link_new)
+    vnet_hw_interface_set_flags (vnm, vui->hw_if_index, link_new ?
+				 VNET_HW_INTERFACE_FLAG_LINK_UP : 0);
+
+  return /* no error */ 0;
+}
+
+/* *INDENT-OFF* */
+VNET_DEVICE_CLASS (vhost_user_device_class) = {
+  .name = "vhost-user",
+  .tx_function_n_errors = VHOST_USER_TX_FUNC_N_ERROR,
+  .tx_function_error_strings = vhost_user_tx_func_error_strings,
+  .format_device_name = format_vhost_user_interface_name,
+  .name_renumber = vhost_user_name_renumber,
+  .admin_up_down_function = vhost_user_interface_admin_up_down,
+  .rx_mode_change_function = vhost_user_interface_rx_mode_change,
+  .format_tx_trace = format_vhost_trace,
+};
+
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/vhost/virtio_std.h b/src/plugins/vhost/virtio_std.h
new file mode 100644
index 00000000000..fa826933a9c
--- /dev/null
+++ b/src/plugins/vhost/virtio_std.h
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __VIRTIO_STD_H__
+#define __VIRTIO_STD_H__
+
+#define foreach_virtio_net_features                                           \
+  _ (VIRTIO_NET_F_CSUM, 0)	 /* Host handles pkts w/ partial csum */      \
+  _ (VIRTIO_NET_F_GUEST_CSUM, 1) /* Guest handles pkts w/ partial csum */     \
+  _ (VIRTIO_NET_F_CTRL_GUEST_OFFLOADS,                                        \
+     2)				     /* Dynamic offload configuration. */     \
+  _ (VIRTIO_NET_F_MTU, 3)	     /* Initial MTU advice. */                \
+  _ (VIRTIO_NET_F_MAC, 5)	     /* Host has given MAC address. */        \
+  _ (VIRTIO_NET_F_GSO, 6)	     /* Host handles pkts w/ any GSO. */      \
+  _ (VIRTIO_NET_F_GUEST_TSO4, 7)     /* Guest can handle TSOv4 in. */         \
+  _ (VIRTIO_NET_F_GUEST_TSO6, 8)     /* Guest can handle TSOv6 in. */         \
+  _ (VIRTIO_NET_F_GUEST_ECN, 9)	     /* Guest can handle TSO[6] w/ ECN in. */ \
+  _ (VIRTIO_NET_F_GUEST_UFO, 10)     /* Guest can handle UFO in. */           \
+  _ (VIRTIO_NET_F_HOST_TSO4, 11)     /* Host can handle TSOv4 in. */          \
+  _ (VIRTIO_NET_F_HOST_TSO6, 12)     /* Host can handle TSOv6 in. */          \
+  _ (VIRTIO_NET_F_HOST_ECN, 13)	     /* Host can handle TSO[6] w/ ECN in. */  \
+  _ (VIRTIO_NET_F_HOST_UFO, 14)	     /* Host can handle UFO in. */            \
+  _ (VIRTIO_NET_F_MRG_RXBUF, 15)     /* Host can merge receive buffers. */    \
+  _ (VIRTIO_NET_F_STATUS, 16)	     /* virtio_net_config.status available */ \
+  _ (VIRTIO_NET_F_CTRL_VQ, 17)	     /* Control channel available */          \
+  _ (VIRTIO_NET_F_CTRL_RX, 18)	     /* Control channel RX mode support */    \
+  _ (VIRTIO_NET_F_CTRL_VLAN, 19)     /* Control channel VLAN filtering */     \
+  _ (VIRTIO_NET_F_CTRL_RX_EXTRA, 20) /* Extra RX mode control support */      \
+  _ (VIRTIO_NET_F_GUEST_ANNOUNCE,                                             \
+     21)		  /* Guest can announce device on the network */      \
+  _ (VIRTIO_NET_F_MQ, 22) /* Device supports Receive Flow Steering */         \
+  _ (VIRTIO_NET_F_CTRL_MAC_ADDR, 23) /* Set MAC address */                    \
+  _ (VIRTIO_F_NOTIFY_ON_EMPTY, 24)                                            \
+  _ (VHOST_F_LOG_ALL, 26) /* Log all write descriptors */                     \
+  _ (VIRTIO_F_ANY_LAYOUT,                                                     \
+     27) /* Can the device handle any descriptor layout */                    \
+  _ (VIRTIO_RING_F_INDIRECT_DESC,                                             \
+     28) /* Support indirect buffer descriptors */                            \
+  _ (VIRTIO_RING_F_EVENT_IDX,                                                 \
+     29) /* The Guest publishes the used index for which it expects an        \
+	  * interrupt at the end of the avail ring. Host should ignore the    \
+	  * avail->flags field. */                                            \
+  /* The Host publishes the avail index for which it expects a kick           \
+   * at the end of the used ring. Guest should ignore the used->flags field.  \
+   */                                                                         \
+  _ (VHOST_USER_F_PROTOCOL_FEATURES, 30)                                      \
+  _ (VIRTIO_F_VERSION_1, 32) /* v1.0 compliant. */                            \
+  _ (VIRTIO_F_IOMMU_PLATFORM, 33)                                             \
+  _ (VIRTIO_F_RING_PACKED, 34)                                                \
+  _ (VIRTIO_F_IN_ORDER, 35) /* all buffers are used by the device in the */   \
+  /* same order in which they have been made available */                     \
+  _ (VIRTIO_F_ORDER_PLATFORM, 36) /* memory accesses by the driver and the */ \
+  /* device are ordered in a way described by the platfor */                  \
+  _ (VIRTIO_F_NOTIFICATION_DATA,                                              \
+     38) /* the driver passes extra data (besides */                          \
+  /* identifying the virtqueue) in its device notifications. */               \
+  _ (VIRTIO_NET_F_SPEED_DUPLEX, 63) /* Device set linkspeed and duplex */
+
+typedef enum
+{
+#define _(f, n) f = n,
+  foreach_virtio_net_features
+#undef _
+} vnet_virtio_net_feature_t;
+
+#define VIRTIO_FEATURE(X) (1ULL << X)
+
+#define VRING_MAX_SIZE 32768
+
+#define VRING_DESC_F_NEXT     1
+#define VRING_DESC_F_WRITE    2
+#define VRING_DESC_F_INDIRECT 4
+
+#define VRING_DESC_F_AVAIL (1 << 7)
+#define VRING_DESC_F_USED  (1 << 15)
+
+#define foreach_virtio_event_idx_flags                                        \
+  _ (VRING_EVENT_F_ENABLE, 0)                                                 \
+  _ (VRING_EVENT_F_DISABLE, 1)                                                \
+  _ (VRING_EVENT_F_DESC, 2)
+
+typedef enum
+{
+#define _(f, n) f = n,
+  foreach_virtio_event_idx_flags
+#undef _
+} vnet_virtio_event_idx_flags_t;
+
+#define VRING_USED_F_NO_NOTIFY	   1
+#define VRING_AVAIL_F_NO_INTERRUPT 1
+
+typedef struct
+{
+  u64 addr;
+  u32 len;
+  u16 flags;
+  u16 next;
+} vnet_virtio_vring_desc_t;
+
+typedef struct
+{
+  u16 flags;
+  u16 idx;
+  u16 ring[0];
+  /*  u16 used_event; */
+} vnet_virtio_vring_avail_t;
+
+typedef struct
+{
+  u32 id;
+  u32 len;
+} vnet_virtio_vring_used_elem_t;
+
+typedef struct
+{
+  u16 flags;
+  u16 idx;
+  vnet_virtio_vring_used_elem_t ring[0];
+  /* u16 avail_event; */
+} vnet_virtio_vring_used_t;
+
+typedef CLIB_PACKED (struct {
+  u64 addr;  // packet data buffer address
+  u32 len;   // packet data buffer size
+  u16 id;    // buffer id
+  u16 flags; // flags
+}) vnet_virtio_vring_packed_desc_t;
+
+STATIC_ASSERT_SIZEOF (vnet_virtio_vring_packed_desc_t, 16);
+
+typedef CLIB_PACKED (struct {
+  u16 off_wrap;
+  u16 flags;
+}) vnet_virtio_vring_desc_event_t;
+
+#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 /* Use csum_start, csum_offset */
+#define VIRTIO_NET_HDR_F_DATA_VALID 2 /* Csum is valid */
+
+#define VIRTIO_NET_HDR_GSO_NONE	 0    /* Not a GSO frame */
+#define VIRTIO_NET_HDR_GSO_TCPV4 1    /* GSO frame, IPv4 TCP (TSO) */
+#define VIRTIO_NET_HDR_GSO_UDP	 3    /* GSO frame, IPv4 UDP (UFO) */
+#define VIRTIO_NET_HDR_GSO_TCPV6 4    /* GSO frame, IPv6 TCP */
+#define VIRTIO_NET_HDR_GSO_ECN	 0x80 /* TCP has ECN set */
+
+typedef CLIB_PACKED (struct {
+  u8 flags;
+  u8 gso_type;
+  u16 hdr_len;	   /* Ethernet + IP + tcp/udp hdrs */
+  u16 gso_size;	   /* Bytes to append to hdr_len per frame */
+  u16 csum_start;  /* Position to start checksumming from */
+  u16 csum_offset; /* Offset after that to place checksum */
+  u16 num_buffers; /* Number of merged rx buffers */
+}) vnet_virtio_net_hdr_v1_t;
+
+typedef CLIB_PACKED (struct {
+  u8 flags;
+  u8 gso_type;
+  u16 hdr_len;
+  u16 gso_size;
+  u16 csum_start;
+  u16 csum_offset;
+}) vnet_virtio_net_hdr_t;
+
+typedef CLIB_PACKED (struct {
+  vnet_virtio_net_hdr_t hdr;
+  u16 num_buffers;
+}) vnet_virtio_net_hdr_mrg_rxbuf_t;
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */