Reorganize source tree to use single autotools instance

Change-Id: I7b51f88292e057c6443b12224486f2d0c9f8ae23
Signed-off-by: Damjan Marion <damarion@cisco.com>

5 files changed, 4078 insertions, 0 deletions

diff --git a/src/vnet/devices/virtio/dir.dox b/src/vnet/devices/virtio/dir.dox
new file mode 100644
index 00000000000..50150799e62
--- /dev/null
+++ b/src/vnet/devices/virtio/dir.dox
@@ -0,0 +1,27 @@
+/*
+ * 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.
+ */
+
+/* Doxygen directory documentation */
+
+/**
+@dir
+@brief vHost User Interface Implementation.
+
+This directory contains the source code for vHost User driver.
+
+*/
+/*? %%clicmd:group_label vHost User %% ?*/
+/*? %%syscfg:group_label vHost User %% ?*/
diff --git a/src/vnet/devices/virtio/vhost-user.c b/src/vnet/devices/virtio/vhost-user.c
new file mode 100644
index 00000000000..bde8106c501
--- /dev/null
+++ b/src/vnet/devices/virtio/vhost-user.c
@@ -0,0 +1,3314 @@
+/*
+ *------------------------------------------------------------------
+ * vhost.c - vhost-user
+ *
+ * Copyright (c) 2014 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/ip/ip.h>
+
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/devices.h>
+#include <vnet/feature/feature.h>
+
+#include <vnet/devices/virtio/vhost-user.h>
+
+/**
+ * @file
+ * @brief vHost User Device Driver.
+ *
+ * This file contains the source code for vHost User interface.
+ */
+
+
+#define VHOST_USER_DEBUG_SOCKET 0
+#define VHOST_DEBUG_VQ 0
+
+#if VHOST_USER_DEBUG_SOCKET == 1
+#define DBG_SOCK(args...) clib_warning(args);
+#else
+#define DBG_SOCK(args...)
+#endif
+
+#if VHOST_DEBUG_VQ == 1
+#define DBG_VQ(args...) clib_warning(args);
+#else
+#define DBG_VQ(args...)
+#endif
+
+/*
+ * 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
+
+#define UNIX_GET_FD(unixfd_idx) \
+    (unixfd_idx != ~0) ? \
+	pool_elt_at_index (unix_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;
+
+vlib_node_registration_t vhost_user_input_node;
+
+#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 char *vhost_user_tx_func_error_strings[] = {
+#define _(n,s) s,
+  foreach_vhost_user_tx_func_error
+#undef _
+};
+
+#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)") \
+  _(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 char *vhost_user_input_func_error_strings[] = {
+#define _(n,s) s,
+  foreach_vhost_user_input_func_error
+#undef _
+};
+
+/* *INDENT-OFF* */
+static vhost_user_main_t vhost_user_main = {
+  .mtu_bytes = 1518,
+};
+
+VNET_HW_INTERFACE_CLASS (vhost_interface_class, static) = {
+  .name = "vhost-user",
+};
+/* *INDENT-ON* */
+
+static 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 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;
+  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;
+
+  DBG_SOCK ("renumbered vhost-user interface dev_instance %d to %d",
+	    hi->dev_instance, new_dev_instance);
+
+  return 0;
+}
+
+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 = __builtin_ctzll (_mm_movemask_epi8 (r));
+
+  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
+  DBG_VQ ("failed to map guest mem addr %llx", addr);
+  *hint = 0;
+  return 0;
+}
+
+static 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;
+}
+
+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;
+  for (i = 0; i < vui->nregions; i++)
+    {
+      if (vui->region_mmap_addr[i] != (void *) -1)
+	{
+
+	  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) & ~(page_sz - 1);
+
+	  r =
+	    munmap (vui->region_mmap_addr[i] - vui->regions[i].mmap_offset,
+		    map_sz);
+
+	  DBG_SOCK
+	    ("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] = (void *) -1;
+
+	  if (r == -1)
+	    {
+	      clib_warning ("failed to unmap memory region (errno %d)",
+			    errno);
+	    }
+	  close (vui->region_mmap_fd[i]);
+	}
+    }
+  vui->nregions = 0;
+}
+
+static void
+vhost_user_tx_thread_placement (vhost_user_intf_t * vui)
+{
+  //Let's try to assign one queue to each thread
+  u32 qid = 0;
+  u32 cpu_index = 0;
+  vui->use_tx_spinlock = 0;
+  while (1)
+    {
+      for (qid = 0; qid < VHOST_VRING_MAX_N / 2; qid++)
+	{
+	  vhost_user_vring_t *rxvq = &vui->vrings[VHOST_VRING_IDX_RX (qid)];
+	  if (!rxvq->started || !rxvq->enabled)
+	    continue;
+
+	  vui->per_cpu_tx_qid[cpu_index] = qid;
+	  cpu_index++;
+	  if (cpu_index == vlib_get_thread_main ()->n_vlib_mains)
+	    return;
+	}
+      //We need to loop, meaning the spinlock has to be used
+      vui->use_tx_spinlock = 1;
+      if (cpu_index == 0)
+	{
+	  //Could not find a single valid one
+	  for (cpu_index = 0;
+	       cpu_index < vlib_get_thread_main ()->n_vlib_mains; cpu_index++)
+	    {
+	      vui->per_cpu_tx_qid[cpu_index] = 0;
+	    }
+	  return;
+	}
+    }
+}
+
+static void
+vhost_user_rx_thread_placement ()
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  vhost_cpu_t *vhc;
+  u32 *workers = 0;
+
+  //Let's list all workers cpu indexes
+  u32 i;
+  for (i = vum->input_cpu_first_index;
+       i < vum->input_cpu_first_index + vum->input_cpu_count; i++)
+    {
+      vlib_node_set_state (vlib_mains ? vlib_mains[i] : &vlib_global_main,
+			   vhost_user_input_node.index,
+			   VLIB_NODE_STATE_DISABLED);
+      vec_add1 (workers, i);
+    }
+
+  vec_foreach (vhc, vum->cpus)
+  {
+    vec_reset_length (vhc->rx_queues);
+  }
+
+  i = 0;
+  vhost_iface_and_queue_t iaq;
+  /* *INDENT-OFF* */
+  pool_foreach (vui, vum->vhost_user_interfaces, {
+      u32 *vui_workers = vec_len (vui->workers) ? vui->workers : workers;
+      u32 qid;
+      for (qid = 0; qid < VHOST_VRING_MAX_N / 2; qid++)
+	{
+	  vhost_user_vring_t *txvq =
+	      &vui->vrings[VHOST_VRING_IDX_TX (qid)];
+	  if (!txvq->started)
+	    continue;
+
+	  i %= vec_len (vui_workers);
+	  u32 cpu_index = vui_workers[i];
+	  i++;
+	  vhc = &vum->cpus[cpu_index];
+
+	  iaq.qid = qid;
+	  iaq.vhost_iface_index = vui - vum->vhost_user_interfaces;
+	  vec_add1 (vhc->rx_queues, iaq);
+	  vlib_node_set_state (vlib_mains ? vlib_mains[cpu_index] :
+	      &vlib_global_main, vhost_user_input_node.index,
+	      VLIB_NODE_STATE_POLLING);
+	}
+  });
+  /* *INDENT-ON* */
+}
+
+static int
+vhost_user_thread_placement (u32 sw_if_index, u32 worker_thread_index, u8 del)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui;
+  vnet_hw_interface_t *hw;
+
+  if (worker_thread_index < vum->input_cpu_first_index ||
+      worker_thread_index >=
+      vum->input_cpu_first_index + vum->input_cpu_count)
+    return -1;
+
+  if (!(hw = vnet_get_sup_hw_interface (vnet_get_main (), sw_if_index)))
+    return -2;
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, hw->dev_instance);
+  u32 found = ~0, *w;
+  vec_foreach (w, vui->workers)
+  {
+    if (*w == worker_thread_index)
+      {
+	found = w - vui->workers;
+	break;
+      }
+  }
+
+  if (del)
+    {
+      if (found == ~0)
+	return -3;
+      vec_del1 (vui->workers, found);
+    }
+  else if (found == ~0)
+    {
+      vec_add1 (vui->workers, worker_thread_index);
+    }
+
+  vhost_user_rx_thread_placement ();
+  return 0;
+}
+
+/** @brief Returns whether at least one TX and one RX vring are enabled */
+int
+vhost_user_intf_ready (vhost_user_intf_t * vui)
+{
+  int i, found[2] = { };	//RX + TX
+
+  for (i = 0; i < VHOST_VRING_MAX_N; i++)
+    if (vui->vrings[i].started && vui->vrings[i].enabled)
+      found[i & 1] = 1;
+
+  return found[0] && found[1];
+}
+
+static void
+vhost_user_update_iface_state (vhost_user_intf_t * vui)
+{
+  /* if we have pointers to descriptor table, go up */
+  int is_up = vhost_user_intf_ready (vui);
+  if (is_up != vui->is_up)
+    {
+      DBG_SOCK ("interface %d %s", vui->sw_if_index,
+		is_up ? "ready" : "down");
+      vnet_hw_interface_set_flags (vnet_get_main (), vui->hw_if_index,
+				   is_up ? VNET_HW_INTERFACE_FLAG_LINK_UP :
+				   0);
+      vui->is_up = is_up;
+    }
+  vhost_user_rx_thread_placement ();
+  vhost_user_tx_thread_placement (vui);
+}
+
+static clib_error_t *
+vhost_user_callfd_read_ready (unix_file_t * uf)
+{
+  __attribute__ ((unused)) int n;
+  u8 buff[8];
+  n = read (uf->file_descriptor, ((char *) &buff), 8);
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_kickfd_read_ready (unix_file_t * uf)
+{
+  __attribute__ ((unused)) int n;
+  u8 buff[8];
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vhost_user_main.vhost_user_interfaces,
+		       uf->private_data >> 8);
+  u32 qid = uf->private_data & 0xff;
+  n = read (uf->file_descriptor, ((char *) &buff), 8);
+  DBG_SOCK ("if %d KICK queue %d", uf->private_data >> 8, qid);
+
+  vlib_worker_thread_barrier_sync (vlib_get_main ());
+  vui->vrings[qid].started = 1;
+  vhost_user_update_iface_state (vui);
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+  return 0;
+}
+
+/**
+ * @brief Try once to lock the vring
+ * @return 0 on success, non-zero on failure.
+ */
+static inline int
+vhost_user_vring_try_lock (vhost_user_intf_t * vui, u32 qid)
+{
+  return __sync_lock_test_and_set (vui->vring_locks[qid], 1);
+}
+
+/**
+ * @brief Spin until the vring is successfully locked
+ */
+static inline void
+vhost_user_vring_lock (vhost_user_intf_t * vui, u32 qid)
+{
+  while (vhost_user_vring_try_lock (vui, qid))
+    ;
+}
+
+/**
+ * @brief Unlock the vring lock
+ */
+static inline void
+vhost_user_vring_unlock (vhost_user_intf_t * vui, u32 qid)
+{
+  *vui->vring_locks[qid] = 0;
+}
+
+static inline void
+vhost_user_vring_init (vhost_user_intf_t * vui, u32 qid)
+{
+  vhost_user_vring_t *vring = &vui->vrings[qid];
+  memset (vring, 0, sizeof (*vring));
+  vring->kickfd_idx = ~0;
+  vring->callfd_idx = ~0;
+  vring->errfd = -1;
+
+  /*
+   * 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 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)
+    {
+      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+					   vring->kickfd_idx);
+      unix_file_del (&unix_main, uf);
+      vring->kickfd_idx = ~0;
+    }
+  if (vring->callfd_idx != ~0)
+    {
+      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+					   vring->callfd_idx);
+      unix_file_del (&unix_main, uf);
+      vring->callfd_idx = ~0;
+    }
+  if (vring->errfd != -1)
+    close (vring->errfd);
+  vhost_user_vring_init (vui, qid);
+}
+
+static 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->unix_file_index != ~0)
+    {
+      unix_file_del (&unix_main, unix_main.file_pool + vui->unix_file_index);
+      vui->unix_file_index = ~0;
+    }
+
+  vui->is_up = 0;
+
+  for (q = 0; q < VHOST_VRING_MAX_N; q++)
+    vhost_user_vring_close (vui, q);
+
+  unmap_all_mem_regions (vui);
+  DBG_SOCK ("interface ifindex %d disconnected", vui->sw_if_index);
+}
+
+#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 & (1 << FEAT_VHOST_F_LOG_ALL))))
+    {
+      return;
+    }
+  if (is_host_address)
+    {
+      addr = (u64) map_user_mem (vui, (uword) addr);
+    }
+  if (PREDICT_FALSE ((addr + len - 1) / VHOST_LOG_PAGE / 8 >= vui->log_size))
+    {
+      DBG_SOCK ("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++;
+    }
+}
+
+static_always_inline void
+vhost_user_log_dirty_pages (vhost_user_intf_t * vui, u64 addr, u64 len)
+{
+  vhost_user_log_dirty_pages_2 (vui, addr, len, 0);
+}
+
+#define vhost_user_log_dirty_ring(vui, vq, member) \
+  if (PREDICT_FALSE(vq->log_used)) { \
+    vhost_user_log_dirty_pages(vui, vq->log_guest_addr + STRUCT_OFFSET_OF(vring_used_t, member), \
+                             sizeof(vq->used->member)); \
+  }
+
+static clib_error_t *
+vhost_user_socket_read (unix_file_t * uf)
+{
+  int n, i;
+  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;
+  unix_file_t template = { 0 };
+  vnet_main_t *vnm = vnet_get_main ();
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data);
+
+  char control[CMSG_SPACE (VHOST_MEMORY_MAX_NREGIONS * sizeof (int))];
+
+  memset (&mh, 0, sizeof (mh));
+  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);
+
+  /* Stop workers to avoid end of the world */
+  vlib_worker_thread_barrier_sync (vlib_get_main ());
+
+  if (n != VHOST_USER_MSG_HDR_SZ)
+    {
+      if (n == -1)
+	{
+	  DBG_SOCK ("recvmsg returned error %d %s", errno, strerror (errno));
+	}
+      else
+	{
+	  DBG_SOCK ("n (%d) != VHOST_USER_MSG_HDR_SZ (%d)",
+		    n, VHOST_USER_MSG_HDR_SZ);
+	}
+      goto close_socket;
+    }
+
+  if (mh.msg_flags & MSG_CTRUNC)
+    {
+      DBG_SOCK ("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 (fds, CMSG_DATA (cmsg), number_of_fds * sizeof (int));
+    }
+
+  /* version 1, no reply bit set */
+  if ((msg.flags & 7) != 1)
+    {
+      DBG_SOCK ("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)
+      {
+	DBG_SOCK ("read failed %s", strerror (errno));
+	goto close_socket;
+      }
+    else if (rv != msg.size)
+      {
+	DBG_SOCK ("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 = (1ULL << FEAT_VIRTIO_NET_F_MRG_RXBUF) |
+	(1ULL << FEAT_VIRTIO_NET_F_CTRL_VQ) |
+	(1ULL << FEAT_VIRTIO_F_ANY_LAYOUT) |
+	(1ULL << FEAT_VIRTIO_F_INDIRECT_DESC) |
+	(1ULL << FEAT_VHOST_F_LOG_ALL) |
+	(1ULL << FEAT_VIRTIO_NET_F_GUEST_ANNOUNCE) |
+	(1ULL << FEAT_VIRTIO_NET_F_MQ) |
+	(1ULL << FEAT_VHOST_USER_F_PROTOCOL_FEATURES) |
+	(1ULL << FEAT_VIRTIO_F_VERSION_1);
+      msg.u64 &= vui->feature_mask;
+      msg.size = sizeof (msg.u64);
+      DBG_SOCK ("if %d msg VHOST_USER_GET_FEATURES - reply 0x%016llx",
+		vui->hw_if_index, msg.u64);
+      break;
+
+    case VHOST_USER_SET_FEATURES:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_FEATURES features 0x%016llx",
+		vui->hw_if_index, msg.u64);
+
+      vui->features = msg.u64;
+
+      if (vui->features &
+	  ((1 << FEAT_VIRTIO_NET_F_MRG_RXBUF) |
+	   (1ULL << FEAT_VIRTIO_F_VERSION_1)))
+	vui->virtio_net_hdr_sz = 12;
+      else
+	vui->virtio_net_hdr_sz = 10;
+
+      vui->is_any_layout =
+	(vui->features & (1 << FEAT_VIRTIO_F_ANY_LAYOUT)) ? 1 : 0;
+
+      ASSERT (vui->virtio_net_hdr_sz < VLIB_BUFFER_PRE_DATA_SIZE);
+      vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
+      vui->is_up = 0;
+
+      /*for (q = 0; q < VHOST_VRING_MAX_N; q++)
+         vhost_user_vring_close(&vui->vrings[q]); */
+
+      break;
+
+    case VHOST_USER_SET_MEM_TABLE:
+      DBG_SOCK ("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))
+	{
+
+	  DBG_SOCK ("number of mem regions must be between 1 and %i",
+		    VHOST_MEMORY_MAX_NREGIONS);
+
+	  goto close_socket;
+	}
+
+      if (msg.memory.nregions != number_of_fds)
+	{
+	  DBG_SOCK ("each memory region must have FD");
+	  goto close_socket;
+	}
+      unmap_all_mem_regions (vui);
+      for (i = 0; i < msg.memory.nregions; i++)
+	{
+	  clib_memcpy (&(vui->regions[i]), &msg.memory.regions[i],
+		       sizeof (vhost_user_memory_region_t));
+
+	  long page_sz = get_huge_page_size (fds[i]);
+
+	  /* align size to 2M page */
+	  ssize_t map_sz = (vui->regions[i].memory_size +
+			    vui->regions[i].mmap_offset +
+			    page_sz) & ~(page_sz - 1);
+
+	  vui->region_mmap_addr[i] = mmap (0, map_sz, PROT_READ | PROT_WRITE,
+					   MAP_SHARED, fds[i], 0);
+	  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;
+
+	  DBG_SOCK
+	    ("map memory region %d addr 0 len 0x%lx fd %d mapped 0x%lx "
+	     "page_sz 0x%x", i, map_sz, fds[i], vui->region_mmap_addr[i],
+	     page_sz);
+
+	  if (vui->region_mmap_addr[i] == MAP_FAILED)
+	    {
+	      clib_warning ("failed to map memory. errno is %d", errno);
+	      goto close_socket;
+	    }
+	  vui->region_mmap_addr[i] += vui->regions[i].mmap_offset;
+	  vui->region_mmap_fd[i] = fds[i];
+	}
+      vui->nregions = msg.memory.nregions;
+      break;
+
+    case VHOST_USER_SET_VRING_NUM:
+      DBG_SOCK ("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 */
+	goto close_socket;
+      vui->vrings[msg.state.index].qsz = msg.state.num;
+      break;
+
+    case VHOST_USER_SET_VRING_ADDR:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_VRING_ADDR idx %d",
+		vui->hw_if_index, msg.state.index);
+
+      if (msg.state.index >= VHOST_VRING_MAX_N)
+	{
+	  DBG_SOCK ("invalid vring index VHOST_USER_SET_VRING_ADDR:"
+		    " %d >= %d", msg.state.index, VHOST_VRING_MAX_N);
+	  goto close_socket;
+	}
+
+      if (msg.size < sizeof (msg.addr))
+	{
+	  DBG_SOCK ("vhost message is too short (%d < %d)",
+		    msg.size, sizeof (msg.addr));
+	  goto close_socket;
+	}
+
+      vui->vrings[msg.state.index].desc = (vring_desc_t *)
+	map_user_mem (vui, msg.addr.desc_user_addr);
+      vui->vrings[msg.state.index].used = (vring_used_t *)
+	map_user_mem (vui, msg.addr.used_user_addr);
+      vui->vrings[msg.state.index].avail = (vring_avail_t *)
+	map_user_mem (vui, msg.addr.avail_user_addr);
+
+      if ((vui->vrings[msg.state.index].desc == NULL) ||
+	  (vui->vrings[msg.state.index].used == NULL) ||
+	  (vui->vrings[msg.state.index].avail == NULL))
+	{
+	  DBG_SOCK ("failed to map user memory for hw_if_index %d",
+		    vui->hw_if_index);
+	  goto close_socket;
+	}
+
+      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 & (1 << FEAT_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;
+
+      /* tell driver that we don't want interrupts */
+      vui->vrings[msg.state.index].used->flags = VRING_USED_F_NO_NOTIFY;
+      break;
+
+    case VHOST_USER_SET_OWNER:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_OWNER", vui->hw_if_index);
+      break;
+
+    case VHOST_USER_RESET_OWNER:
+      DBG_SOCK ("if %d msg VHOST_USER_RESET_OWNER", vui->hw_if_index);
+      break;
+
+    case VHOST_USER_SET_VRING_CALL:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_VRING_CALL u64 %d",
+		vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+
+      /* if there is old fd, delete and close it */
+      if (vui->vrings[q].callfd_idx != ~0)
+	{
+	  unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+					       vui->vrings[q].callfd_idx);
+	  unix_file_del (&unix_main, uf);
+	  vui->vrings[q].callfd_idx = ~0;
+	}
+
+      if (!(msg.u64 & 0x100))
+	{
+	  if (number_of_fds != 1)
+	    {
+	      DBG_SOCK ("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;
+	  vui->vrings[q].callfd_idx = unix_file_add (&unix_main, &template);
+	}
+      else
+	vui->vrings[q].callfd_idx = ~0;
+      break;
+
+    case VHOST_USER_SET_VRING_KICK:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_VRING_KICK u64 %d",
+		vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+
+      if (vui->vrings[q].kickfd_idx != ~0)
+	{
+	  unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+					       vui->vrings[q].kickfd_idx);
+	  unix_file_del (&unix_main, uf);
+	  vui->vrings[q].kickfd_idx = ~0;
+	}
+
+      if (!(msg.u64 & 0x100))
+	{
+	  if (number_of_fds != 1)
+	    {
+	      DBG_SOCK ("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 = unix_file_add (&unix_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;
+	}
+
+      break;
+
+    case VHOST_USER_SET_VRING_ERR:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_VRING_ERR u64 %d",
+		vui->hw_if_index, msg.u64);
+
+      q = (u8) (msg.u64 & 0xFF);
+
+      if (vui->vrings[q].errfd != -1)
+	close (vui->vrings[q].errfd);
+
+      if (!(msg.u64 & 0x100))
+	{
+	  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:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_VRING_BASE idx %d num %d",
+		vui->hw_if_index, msg.state.index, msg.state.num);
+
+      vui->vrings[msg.state.index].last_avail_idx = msg.state.num;
+      break;
+
+    case VHOST_USER_GET_VRING_BASE:
+      DBG_SOCK ("if %d msg VHOST_USER_GET_VRING_BASE idx %d num %d",
+		vui->hw_if_index, msg.state.index, msg.state.num);
+
+      if (msg.state.index >= VHOST_VRING_MAX_N)
+	{
+	  DBG_SOCK ("invalid vring index VHOST_USER_GET_VRING_BASE:"
+		    " %d >= %d", msg.state.index, VHOST_VRING_MAX_N);
+	  goto close_socket;
+	}
+
+      /* Spec says: Client must [...] stop ring upon receiving VHOST_USER_GET_VRING_BASE. */
+      vhost_user_vring_close (vui, msg.state.index);
+
+      msg.state.num = vui->vrings[msg.state.index].last_avail_idx;
+      msg.flags |= 4;
+      msg.size = sizeof (msg.state);
+      break;
+
+    case VHOST_USER_NONE:
+      DBG_SOCK ("if %d msg VHOST_USER_NONE", vui->hw_if_index);
+
+      break;
+
+    case VHOST_USER_SET_LOG_BASE:
+      {
+	DBG_SOCK ("if %d msg VHOST_USER_SET_LOG_BASE", vui->hw_if_index);
+
+	if (msg.size != sizeof (msg.log))
+	  {
+	    DBG_SOCK
+	      ("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)))
+	  {
+	    DBG_SOCK
+	      ("VHOST_USER_PROTOCOL_F_LOG_SHMFD not set but VHOST_USER_SET_LOG_BASE received");
+	    goto close_socket;
+	  }
+
+	fd = fds[0];
+	/* align size to 2M page */
+	long page_sz = get_huge_page_size (fd);
+	ssize_t map_sz =
+	  (msg.log.size + msg.log.offset + page_sz) & ~(page_sz - 1);
+
+	vui->log_base_addr = mmap (0, map_sz, PROT_READ | PROT_WRITE,
+				   MAP_SHARED, fd, 0);
+
+	DBG_SOCK
+	  ("map log region addr 0 len 0x%lx off 0x%lx fd %d mapped 0x%lx",
+	   map_sz, msg.log.offset, fd, vui->log_base_addr);
+
+	if (vui->log_base_addr == MAP_FAILED)
+	  {
+	    clib_warning ("failed to map memory. errno is %d", errno);
+	    goto close_socket;
+	  }
+
+	vui->log_base_addr += msg.log.offset;
+	vui->log_size = msg.log.size;
+
+	msg.flags |= 4;
+	msg.size = sizeof (msg.u64);
+
+	break;
+      }
+
+    case VHOST_USER_SET_LOG_FD:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_LOG_FD", vui->hw_if_index);
+
+      break;
+
+    case VHOST_USER_GET_PROTOCOL_FEATURES:
+      DBG_SOCK ("if %d msg VHOST_USER_GET_PROTOCOL_FEATURES",
+		vui->hw_if_index);
+
+      msg.flags |= 4;
+      msg.u64 = (1 << VHOST_USER_PROTOCOL_F_LOG_SHMFD) |
+	(1 << VHOST_USER_PROTOCOL_F_MQ);
+      msg.size = sizeof (msg.u64);
+      break;
+
+    case VHOST_USER_SET_PROTOCOL_FEATURES:
+      DBG_SOCK ("if %d msg VHOST_USER_SET_PROTOCOL_FEATURES features 0x%lx",
+		vui->hw_if_index, msg.u64);
+
+      vui->protocol_features = msg.u64;
+
+      break;
+
+    case VHOST_USER_GET_QUEUE_NUM:
+      DBG_SOCK ("if %d msg VHOST_USER_GET_QUEUE_NUM", vui->hw_if_index);
+      msg.flags |= 4;
+      msg.u64 = VHOST_VRING_MAX_N;
+      msg.size = sizeof (msg.u64);
+      break;
+
+    case VHOST_USER_SET_VRING_ENABLE:
+      DBG_SOCK ("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 >= VHOST_VRING_MAX_N)
+	{
+	  DBG_SOCK ("invalid vring index VHOST_USER_SET_VRING_ENABLE:"
+		    " %d >= %d", msg.state.index, VHOST_VRING_MAX_N);
+	  goto close_socket;
+	}
+
+      vui->vrings[msg.state.index].enabled = msg.state.num;
+      break;
+
+    default:
+      DBG_SOCK ("unknown vhost-user message %d received. closing socket",
+		msg.request);
+      goto close_socket;
+    }
+
+  /* if we need to reply */
+  if (msg.flags & 4)
+    {
+      n =
+	send (uf->file_descriptor, &msg, VHOST_USER_MSG_HDR_SZ + msg.size, 0);
+      if (n != (msg.size + VHOST_USER_MSG_HDR_SZ))
+	{
+	  DBG_SOCK ("could not send message response");
+	  goto close_socket;
+	}
+    }
+
+  vhost_user_update_iface_state (vui);
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+  return 0;
+
+close_socket:
+  vhost_user_if_disconnect (vui);
+  vhost_user_update_iface_state (vui);
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_socket_error (unix_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);
+
+  DBG_SOCK ("socket error on if %d", vui->sw_if_index);
+  vlib_worker_thread_barrier_sync (vm);
+  vhost_user_if_disconnect (vui);
+  vhost_user_rx_thread_placement ();
+  vlib_worker_thread_barrier_release (vm);
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_socksvr_accept_ready (unix_file_t * uf)
+{
+  int client_fd, client_len;
+  struct sockaddr_un client;
+  unix_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");
+
+  DBG_SOCK ("New client socket for vhost interface %d", vui->sw_if_index);
+  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;
+  vui->unix_file_index = unix_file_add (&unix_main, &template);
+  return 0;
+}
+
+static clib_error_t *
+vhost_user_init (vlib_main_t * vm)
+{
+  clib_error_t *error;
+  vhost_user_main_t *vum = &vhost_user_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  vlib_thread_registration_t *tr;
+  uword *p;
+
+  error = vlib_call_init_function (vm, ip4_init);
+  if (error)
+    return error;
+
+  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;
+  }
+
+  /* find out which cpus will be used for input */
+  vum->input_cpu_first_index = 0;
+  vum->input_cpu_count = 1;
+  p = hash_get_mem (tm->thread_registrations_by_name, "workers");
+  tr = p ? (vlib_thread_registration_t *) p[0] : 0;
+
+  if (tr && tr->count > 0)
+    {
+      vum->input_cpu_first_index = tr->first_index;
+      vum->input_cpu_count = tr->count;
+    }
+
+  vum->random = random_default_seed ();
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (vhost_user_init);
+
+static clib_error_t *
+vhost_user_exit (vlib_main_t * vm)
+{
+  /* TODO cleanup */
+  return 0;
+}
+
+VLIB_MAIN_LOOP_EXIT_FUNCTION (vhost_user_exit);
+
+static 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 = pool_elt_at_index (vum->vhost_user_interfaces,
+					      t->device_index);
+
+  vnet_sw_interface_t *sw = vnet_get_sw_interface (vnm, vui->sw_if_index);
+
+  uword 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;
+}
+
+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)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u32 qsz_mask = txvq->qsz - 1;
+  u32 last_avail_idx = txvq->last_avail_idx;
+  u32 desc_current = txvq->avail->ring[last_avail_idx & qsz_mask];
+  vring_desc_t *hdr_desc = 0;
+  virtio_net_hdr_mrg_rxbuf_t *hdr;
+  u32 hint = 0;
+
+  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 & VIRTQ_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 & VIRTQ_DESC_F_NEXT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+    }
+  if (!(txvq->desc[desc_current].flags & VIRTQ_DESC_F_NEXT) &&
+      !(txvq->desc[desc_current].flags & VIRTQ_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 inline void
+vhost_user_send_call (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 __attribute__ ((unused));
+  /* TODO: pay attention to rv */
+  rv = write (fd, &x, sizeof (x));
+  vq->n_since_last_int = 0;
+  vq->int_deadline = vlib_time_now (vm) + vum->coalesce_time;
+}
+
+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 (src2, 64, LOAD);
+	  CLIB_PREFETCH (src3, 64, LOAD);
+
+	  clib_memcpy ((void *) cpy[0].dst, src0, cpy[0].len);
+	  clib_memcpy ((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 ((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.
+ */
+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 qsz_mask = txvq->qsz - 1;
+  while (discarded_packets != discard_max)
+    {
+      if (avail_idx == txvq->last_avail_idx)
+	goto out;
+
+      u16 desc_chain_head =
+	txvq->avail->ring[txvq->last_avail_idx & qsz_mask];
+      txvq->last_avail_idx++;
+      txvq->used->ring[txvq->last_used_idx & qsz_mask].id = desc_chain_head;
+      txvq->used->ring[txvq->last_used_idx & qsz_mask].len = 0;
+      vhost_user_log_dirty_ring (vui, txvq,
+				 ring[txvq->last_used_idx & qsz_mask]);
+      txvq->last_used_idx++;
+      discarded_packets++;
+    }
+
+out:
+  CLIB_MEMORY_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 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;
+    }
+}
+
+static 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)
+{
+  vhost_user_vring_t *txvq = &vui->vrings[VHOST_VRING_IDX_TX (qid)];
+  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);
+  u16 qsz_mask;
+  u32 map_hint = 0;
+  u16 cpu_index = os_get_cpu_number ();
+  u16 copy_len = 0;
+
+  {
+    /* do we have pending interrupts ? */
+    vhost_user_vring_t *rxvq = &vui->vrings[VHOST_VRING_IDX_RX (qid)];
+    f64 now = vlib_time_now (vm);
+
+    if ((txvq->n_since_last_int) && (txvq->int_deadline < now))
+      vhost_user_send_call (vm, txvq);
+
+    if ((rxvq->n_since_last_int) && (rxvq->int_deadline < now))
+      vhost_user_send_call (vm, rxvq);
+  }
+
+  if (PREDICT_FALSE (txvq->avail->flags & 0xFFFE))
+    return 0;
+
+  n_left = (u16) (txvq->avail->idx - txvq->last_avail_idx);
+
+  /* nothing to do */
+  if (PREDICT_FALSE (n_left == 0))
+    return 0;
+
+  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);
+      return 0;
+    }
+
+  if (PREDICT_FALSE (n_left == txvq->qsz))
+    {
+      /*
+       * 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);
+    }
+
+  qsz_mask = txvq->qsz - 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 yeld 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.
+   */
+  if (PREDICT_FALSE (vum->cpus[cpu_index].rx_buffers_len < n_left + 1))
+    {
+      u32 curr_len = vum->cpus[cpu_index].rx_buffers_len;
+      vum->cpus[cpu_index].rx_buffers_len +=
+	vlib_buffer_alloc_from_free_list (vm,
+					  vum->cpus[cpu_index].rx_buffers +
+					  curr_len,
+					  VHOST_USER_RX_BUFFERS_N - curr_len,
+					  VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);
+
+      if (PREDICT_FALSE
+	  (vum->cpus[cpu_index].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 > vum->cpus[cpu_index].rx_buffers_len) ?
+	    n_left + 1 - vum->cpus[cpu_index].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,
+					 os_get_cpu_number (),
+					 vui->sw_if_index, flush);
+
+	  vlib_error_count (vm, vhost_user_input_node.index,
+			    VHOST_USER_INPUT_FUNC_ERROR_NO_BUFFER, flush);
+	}
+    }
+
+  while (n_left > 0)
+    {
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      while (n_left > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t *b_head, *b_current;
+	  u32 bi_current;
+	  u16 desc_current;
+	  u32 desc_data_offset;
+	  vring_desc_t *desc_table = txvq->desc;
+
+	  if (PREDICT_FALSE (vum->cpus[cpu_index].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[txvq->last_avail_idx & qsz_mask];
+	  vum->cpus[cpu_index].rx_buffers_len--;
+	  bi_current = (vum->cpus[cpu_index].rx_buffers)
+	    [vum->cpus[cpu_index].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,
+					   (vum->cpus[cpu_index].rx_buffers)
+					   [vum->cpus[cpu_index].
+					    rx_buffers_len - 1], LOAD);
+
+	  /* Just preset the used descriptor id and length for later */
+	  txvq->used->ring[txvq->last_used_idx & qsz_mask].id = desc_current;
+	  txvq->used->ring[txvq->last_used_idx & qsz_mask].len = 0;
+	  vhost_user_log_dirty_ring (vui, txvq,
+				     ring[txvq->last_used_idx & qsz_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))
+	    {
+	      //TODO: next_index is not exactly known at that point
+	      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);
+	      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 & VIRTQ_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))
+		{
+		  //FIXME: Handle error by shutdown the queue
+		  goto out;
+		}
+	    }
+
+	  if (PREDICT_TRUE (vui->is_any_layout) ||
+	      (!(desc_table[desc_current].flags & VIRTQ_DESC_F_NEXT)))
+	    {
+	      /* ANYLAYOUT or single buffer */
+	      desc_data_offset = vui->virtio_net_hdr_sz;
+	    }
+	  else
+	    {
+	      /* CSR case without ANYLAYOUT, skip 1st buffer */
+	      desc_data_offset = desc_table[desc_current].len;
+	    }
+
+	  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 &
+				     VIRTQ_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 == VLIB_BUFFER_DATA_SIZE))
+		{
+		  if (PREDICT_FALSE
+		      (vum->cpus[cpu_index].rx_buffers_len == 0))
+		    {
+		      /*
+		       * 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,
+						       &vum->cpus[cpu_index],
+						       b_head);
+		      n_left = 0;
+		      goto stop;
+		    }
+
+		  /* Get next output */
+		  vum->cpus[cpu_index].rx_buffers_len--;
+		  u32 bi_next =
+		    (vum->cpus[cpu_index].rx_buffers)[vum->cpus
+						      [cpu_index].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 */
+	      vhost_copy_t *cpy = &vum->cpus[cpu_index].copy[copy_len];
+	      copy_len++;
+	      u32 desc_data_l =
+		desc_table[desc_current].len - desc_data_offset;
+	      cpy->len = VLIB_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);
+	      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:
+	  CLIB_PREFETCH (&n_left, sizeof (n_left), LOAD);
+
+	  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 */
+	  txvq->last_avail_idx++;
+	  txvq->last_used_idx++;
+
+	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b_head);
+
+	  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;
+
+	  {
+	    u32 next0 = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
+
+	    /* redirect if feature path enabled */
+	    vnet_feature_start_device_input_x1 (vui->sw_if_index, &next0,
+						b_head, 0);
+
+	    u32 bi = to_next[-1];	//Cannot use to_next[-1] in the macro
+	    vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					     to_next, n_left_to_next,
+					     bi, next0);
+	  }
+
+	  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, vum->cpus[cpu_index].copy,
+					  copy_len, &map_hint)))
+		{
+		  clib_warning
+		    ("Memory mapping error on interface hw_if_index=%d "
+		     "(Shutting down - Switch interface down and up to restart)",
+		     vui->hw_if_index);
+		  vui->admin_up = 0;
+		  copy_len = 0;
+		  break;
+		}
+	      copy_len = 0;
+
+	      /* give buffers back to driver */
+	      CLIB_MEMORY_BARRIER ();
+	      txvq->used->idx = txvq->last_used_idx;
+	      vhost_user_log_dirty_ring (vui, txvq, idx);
+	    }
+	}
+    stop:
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  /* Do the memory copies */
+  if (PREDICT_FALSE
+      (vhost_user_input_copy (vui, vum->cpus[cpu_index].copy,
+			      copy_len, &map_hint)))
+    {
+      clib_warning ("Memory mapping error on interface hw_if_index=%d "
+		    "(Shutting down - Switch interface down and up to restart)",
+		    vui->hw_if_index);
+      vui->admin_up = 0;
+    }
+
+  /* give buffers back to driver */
+  CLIB_MEMORY_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 & 1))
+    {
+      txvq->n_since_last_int += n_rx_packets;
+
+      if (txvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, txvq);
+    }
+
+  /* increase rx counters */
+  vlib_increment_combined_counter
+    (vnet_main.interface_main.combined_sw_if_counters
+     + VNET_INTERFACE_COUNTER_RX,
+     os_get_cpu_number (), vui->sw_if_index, n_rx_packets, n_rx_bytes);
+
+  return n_rx_packets;
+}
+
+static uword
+vhost_user_input (vlib_main_t * vm,
+		  vlib_node_runtime_t * node, vlib_frame_t * f)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  uword n_rx_packets = 0;
+  u32 cpu_index = os_get_cpu_number ();
+
+
+  vhost_iface_and_queue_t *vhiq;
+  vec_foreach (vhiq, vum->cpus[cpu_index].rx_queues)
+  {
+    vhost_user_intf_t *vui =
+      &vum->vhost_user_interfaces[vhiq->vhost_iface_index];
+    n_rx_packets += vhost_user_if_input (vm, vum, vui, vhiq->qid, node);
+  }
+
+  return n_rx_packets;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (vhost_user_input_node) = {
+  .function = vhost_user_input,
+  .type = VLIB_NODE_TYPE_INPUT,
+  .name = "vhost-user-input",
+  .sibling_of = "device-input",
+
+  /* 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,
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (vhost_user_input_node, vhost_user_input)
+/* *INDENT-ON* */
+
+
+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 qsz_mask = rxvq->qsz - 1;
+  u32 last_avail_idx = rxvq->last_avail_idx;
+  u32 desc_current = rxvq->avail->ring[last_avail_idx & qsz_mask];
+  vring_desc_t *hdr_desc = 0;
+  u32 hint = 0;
+
+  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 & VIRTQ_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 & VIRTQ_DESC_F_NEXT)
+    {
+      t->virtio_ring_flags |= 1 << VIRTIO_TRACE_F_SIMPLE_CHAINED;
+    }
+  if (!(rxvq->desc[desc_current].flags & VIRTQ_DESC_F_NEXT) &&
+      !(rxvq->desc[desc_current].flags & VIRTQ_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 ((void *) cpy[2].src, 64, LOAD);
+	  CLIB_PREFETCH ((void *) cpy[3].src, 64, LOAD);
+
+	  clib_memcpy (dst0, (void *) cpy[0].src, cpy[0].len);
+	  clib_memcpy (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 (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 uword
+vhost_user_tx (vlib_main_t * vm,
+	       vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 *buffers = vlib_frame_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 = ~0;
+  vhost_user_vring_t *rxvq;
+  u16 qsz_mask;
+  u8 error;
+  u32 cpu_index = os_get_cpu_number ();
+  u32 map_hint = 0;
+  u8 retry = 8;
+  u16 copy_len;
+  u16 tx_headers_len;
+
+  if (PREDICT_FALSE (!vui->admin_up))
+    {
+      error = VHOST_USER_TX_FUNC_ERROR_DOWN;
+      goto done3;
+    }
+
+  if (PREDICT_FALSE (!vui->is_up))
+    {
+      error = VHOST_USER_TX_FUNC_ERROR_NOT_READY;
+      goto done3;
+    }
+
+  qid =
+    VHOST_VRING_IDX_RX (*vec_elt_at_index
+			(vui->per_cpu_tx_qid, os_get_cpu_number ()));
+  rxvq = &vui->vrings[qid];
+  if (PREDICT_FALSE (vui->use_tx_spinlock))
+    vhost_user_vring_lock (vui, qid);
+
+  qsz_mask = rxvq->qsz - 1;	/* qsz is always power of 2 */
+
+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;
+      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))
+	{
+	  vum->cpus[cpu_index].current_trace =
+	    vlib_add_trace (vm, node, b0,
+			    sizeof (*vum->cpus[cpu_index].current_trace));
+	  vhost_user_tx_trace (vum->cpus[cpu_index].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 & 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 & VIRTQ_DESC_F_INDIRECT))
+	{
+	  if (PREDICT_FALSE
+	      (rxvq->desc[desc_head].len < sizeof (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
+	virtio_net_hdr_mrg_rxbuf_t *hdr =
+	  &vum->cpus[cpu_index].tx_headers[tx_headers_len];
+	tx_headers_len++;
+	hdr->hdr.flags = 0;
+	hdr->hdr.gso_type = 0;
+	hdr->num_buffers = 1;	//This is local, no need to check
+
+	// Prepare a copy order executed later for the header
+	vhost_copy_t *cpy = &vum->cpus[cpu_index].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 & VIRTQ_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
+		{
+		  virtio_net_hdr_mrg_rxbuf_t *hdr =
+		    &vum->cpus[cpu_index].tx_headers[tx_headers_len - 1];
+
+		  //Move from available to used buffer
+		  rxvq->used->ring[rxvq->last_used_idx & qsz_mask].id =
+		    desc_head;
+		  rxvq->used->ring[rxvq->last_used_idx & qsz_mask].len =
+		    desc_len;
+		  vhost_user_log_dirty_ring (vui, rxvq,
+					     ring[rxvq->last_used_idx &
+						  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 & qsz_mask];
+		  if (PREDICT_FALSE
+		      (rxvq->desc[desc_head].flags & VIRTQ_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 (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;
+		}
+	    }
+
+	  {
+	    vhost_copy_t *cpy = &vum->cpus[cpu_index].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 (&rxvq->desc, CLIB_CACHE_LINE_BYTES, LOAD);
+	  }
+
+	  // 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 & qsz_mask].id = desc_head;
+      rxvq->used->ring[rxvq->last_used_idx & qsz_mask].len = desc_len;
+      vhost_user_log_dirty_ring (vui, rxvq,
+				 ring[rxvq->last_used_idx & qsz_mask]);
+      rxvq->last_avail_idx++;
+      rxvq->last_used_idx++;
+
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+	{
+	  vum->cpus[cpu_index].current_trace->hdr =
+	    vum->cpus[cpu_index].tx_headers[tx_headers_len - 1];
+	}
+
+      n_left--;			//At the end for error counting when 'goto done' is invoked
+      buffers++;
+    }
+
+done:
+  //Do the memory copies
+  if (PREDICT_FALSE
+      (vhost_user_tx_copy (vui, vum->cpus[cpu_index].copy,
+			   copy_len, &map_hint)))
+    {
+      clib_warning ("Memory mapping error on interface hw_if_index=%d "
+		    "(Shutting down - Switch interface down and up to restart)",
+		    vui->hw_if_index);
+      vui->admin_up = 0;
+    }
+
+  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 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;
+    }
+
+  /* interrupt (call) handling */
+  if ((rxvq->callfd_idx != ~0) && !(rxvq->avail->flags & 1))
+    {
+      rxvq->n_since_last_int += frame->n_vectors - n_left;
+
+      if (rxvq->n_since_last_int > vum->coalesce_frames)
+	vhost_user_send_call (vm, rxvq);
+    }
+
+  vhost_user_vring_unlock (vui, qid);
+
+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,
+	 os_get_cpu_number (), vui->sw_if_index, n_left);
+    }
+
+  vlib_buffer_free (vm, vlib_frame_args (frame), frame->n_vectors);
+  return frame->n_vectors;
+}
+
+static 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);
+  uword is_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
+  vhost_user_main_t *vum = &vhost_user_main;
+  vhost_user_intf_t *vui =
+    pool_elt_at_index (vum->vhost_user_interfaces, hif->dev_instance);
+
+  vui->admin_up = is_up;
+
+  if (is_up)
+    vnet_hw_interface_set_flags (vnm, vui->hw_if_index,
+				 VNET_HW_INTERFACE_FLAG_LINK_UP);
+
+  return /* no error */ 0;
+}
+
+/* *INDENT-OFF* */
+VNET_DEVICE_CLASS (vhost_user_dev_class,static) = {
+  .name = "vhost-user",
+  .tx_function = vhost_user_tx,
+  .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,
+  .format_tx_trace = format_vhost_trace,
+};
+
+VLIB_DEVICE_TX_FUNCTION_MULTIARCH (vhost_user_dev_class,
+				   vhost_user_tx)
+/* *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;
+  unix_file_t template = { 0 };
+  f64 timeout = 3153600000.0 /* 100 years */ ;
+  uword *event_data = 0;
+
+  sockfd = socket (AF_UNIX, SOCK_STREAM, 0);
+  sun.sun_family = AF_UNIX;
+  template.read_function = vhost_user_socket_read;
+  template.error_function = vhost_user_socket_error;
+
+  if (sockfd < 0)
+    return 0;
+
+  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->unix_file_index == ~0)
+		{
+		  /* try to connect */
+		  strncpy (sun.sun_path, (char *) vui->sock_filename,
+			   sizeof (sun.sun_path) - 1);
+
+		  if (connect (sockfd, (struct sockaddr *) &sun,
+			       sizeof (struct sockaddr_un)) == 0)
+		    {
+		      vui->sock_errno = 0;
+		      template.file_descriptor = sockfd;
+		      template.private_data =
+			  vui - vhost_user_main.vhost_user_interfaces;
+		      vui->unix_file_index = unix_file_add (&unix_main, &template);
+
+		      //Re-open for next connect
+		      if ((sockfd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0) {
+			  clib_warning("Critical: Could not open unix socket");
+			  return 0;
+		      }
+		    }
+		  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->unix_file_index);
+		  int retval =
+		      getsockopt (fd, SOL_SOCKET, SO_ERROR, &error, &len);
+
+		  if (retval)
+		    {
+		      DBG_SOCK ("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)
+{
+  // Delete configured thread pinning
+  vec_reset_length (vui->workers);
+  // disconnect interface sockets
+  vhost_user_if_disconnect (vui);
+  vhost_user_update_iface_state (vui);
+
+  if (vui->unix_server_index != ~0)
+    {
+      //Close server socket
+      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+					   vui->unix_server_index);
+      unix_file_del (&unix_main, uf);
+      vui->unix_server_index = ~0;
+    }
+}
+
+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;
+
+  if (!(hwif = vnet_get_sup_hw_interface (vnm, sw_if_index)) ||
+      hwif->dev_class_index != vhost_user_dev_class.index)
+    return VNET_API_ERROR_INVALID_SW_IF_INDEX;
+
+  DBG_SOCK ("Deleting vhost-user interface %s (instance %d)",
+	    hwif->name, hwif->dev_instance);
+
+  vui = pool_elt_at_index (vum->vhost_user_interfaces, hwif->dev_instance);
+
+  // Disable and reset interface
+  vhost_user_term_if (vui);
+
+  // Back to pool
+  pool_put (vum->vhost_user_interfaces, 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);
+  return rv;
+}
+
+/**
+ * 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, u8 * hwaddress)
+{
+  vhost_user_main_t *vum = &vhost_user_main;
+  u8 hwaddr[6];
+  clib_error_t *error;
+
+  /* create hw and sw interface */
+  if (hwaddress)
+    {
+      clib_memcpy (hwaddr, hwaddress, 6);
+    }
+  else
+    {
+      random_u32 (&vum->random);
+      clib_memcpy (hwaddr + 2, &vum->random, sizeof (vum->random));
+      hwaddr[0] = 2;
+      hwaddr[1] = 0xfe;
+    }
+
+  error = ethernet_register_interface
+    (vnm,
+     vhost_user_dev_class.index,
+     vui - vum->vhost_user_interfaces /* device instance */ ,
+     hwaddr /* ethernet address */ ,
+     &vui->hw_if_index, 0 /* flag change */ );
+
+  if (error)
+    clib_error_report (error);
+
+  vnet_hw_interface_t *hi = vnet_get_hw_interface (vnm, vui->hw_if_index);
+  hi->max_l3_packet_bytes[VLIB_RX] = hi->max_l3_packet_bytes[VLIB_TX] = 9000;
+}
+
+/*
+ *  Initialize vui with specified attributes
+ */
+static void
+vhost_user_vui_init (vnet_main_t * vnm,
+		     vhost_user_intf_t * vui,
+		     int server_sock_fd,
+		     const char *sock_filename,
+		     u64 feature_mask, u32 * sw_if_index)
+{
+  vnet_sw_interface_t *sw;
+  sw = vnet_get_hw_sw_interface (vnm, vui->hw_if_index);
+  int q;
+
+  if (server_sock_fd != -1)
+    {
+      unix_file_t template = { 0 };
+      template.read_function = vhost_user_socksvr_accept_ready;
+      template.file_descriptor = server_sock_fd;
+      template.private_data = vui - vhost_user_main.vhost_user_interfaces;	//hw index
+      vui->unix_server_index = unix_file_add (&unix_main, &template);
+    }
+  else
+    {
+      vui->unix_server_index = ~0;
+    }
+
+  vui->sw_if_index = sw->sw_if_index;
+  strncpy (vui->sock_filename, sock_filename,
+	   ARRAY_LEN (vui->sock_filename) - 1);
+  vui->sock_errno = 0;
+  vui->is_up = 0;
+  vui->feature_mask = feature_mask;
+  vui->unix_file_index = ~0;
+  vui->log_base_addr = 0;
+
+  for (q = 0; q < VHOST_VRING_MAX_N; q++)
+    vhost_user_vring_init (vui, q);
+
+  vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
+
+  if (sw_if_index)
+    *sw_if_index = vui->sw_if_index;
+
+  for (q = 0; q < VHOST_VRING_MAX_N; q++)
+    {
+      vui->vring_locks[q] = clib_mem_alloc_aligned (CLIB_CACHE_LINE_BYTES,
+						    CLIB_CACHE_LINE_BYTES);
+      memset ((void *) vui->vring_locks[q], 0, CLIB_CACHE_LINE_BYTES);
+    }
+
+  vec_validate (vui->per_cpu_tx_qid,
+		vlib_get_thread_main ()->n_vlib_mains - 1);
+  vhost_user_tx_thread_placement (vui);
+}
+
+int
+vhost_user_create_if (vnet_main_t * vnm, vlib_main_t * vm,
+		      const char *sock_filename,
+		      u8 is_server,
+		      u32 * sw_if_index,
+		      u64 feature_mask,
+		      u8 renumber, u32 custom_dev_instance, u8 * hwaddr)
+{
+  vhost_user_intf_t *vui = NULL;
+  u32 sw_if_idx = ~0;
+  int rv = 0;
+  int server_sock_fd = -1;
+
+  if (is_server)
+    {
+      if ((rv =
+	   vhost_user_init_server_sock (sock_filename, &server_sock_fd)) != 0)
+	{
+	  return rv;
+	}
+    }
+
+  pool_get (vhost_user_main.vhost_user_interfaces, vui);
+
+  vhost_user_create_ethernet (vnm, vm, vui, hwaddr);
+  vhost_user_vui_init (vnm, vui, server_sock_fd, sock_filename,
+		       feature_mask, &sw_if_idx);
+
+  if (renumber)
+    vnet_interface_name_renumber (sw_if_idx, custom_dev_instance);
+
+  if (sw_if_index)
+    *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,
+		      const char *sock_filename,
+		      u8 is_server,
+		      u32 sw_if_index,
+		      u64 feature_mask, u8 renumber, u32 custom_dev_instance)
+{
+  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;
+
+  if (!(hwif = vnet_get_sup_hw_interface (vnm, sw_if_index)) ||
+      hwif->dev_class_index != vhost_user_dev_class.index)
+    return VNET_API_ERROR_INVALID_SW_IF_INDEX;
+
+  vui = vec_elt_at_index (vum->vhost_user_interfaces, hwif->dev_instance);
+
+  // First try to open server socket
+  if (is_server)
+    if ((rv = vhost_user_init_server_sock (sock_filename,
+					   &server_sock_fd)) != 0)
+      return rv;
+
+  vhost_user_term_if (vui);
+  vhost_user_vui_init (vnm, vui, server_sock_fd,
+		       sock_filename, feature_mask, &sw_if_idx);
+
+  if (renumber)
+    vnet_interface_name_renumber (sw_if_idx, 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)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  u8 *sock_filename = NULL;
+  u32 sw_if_index;
+  u8 is_server = 0;
+  u64 feature_mask = (u64) ~ (0ULL);
+  u8 renumber = 0;
+  u32 custom_dev_instance = ~0;
+  u8 hwaddr[6];
+  u8 *hw = 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, "socket %s", &sock_filename))
+	;
+      else if (unformat (line_input, "server"))
+	is_server = 1;
+      else if (unformat (line_input, "feature-mask 0x%llx", &feature_mask))
+	;
+      else
+	if (unformat
+	    (line_input, "hwaddr %U", unformat_ethernet_address, hwaddr))
+	hw = hwaddr;
+      else if (unformat (line_input, "renumber %d", &custom_dev_instance))
+	{
+	  renumber = 1;
+	}
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+  unformat_free (line_input);
+
+  vnet_main_t *vnm = vnet_get_main ();
+
+  int rv;
+  if ((rv = vhost_user_create_if (vnm, vm, (char *) sock_filename,
+				  is_server, &sw_if_index, feature_mask,
+				  renumber, custom_dev_instance, hw)))
+    {
+      vec_free (sock_filename);
+      return clib_error_return (0, "vhost_user_create_if returned %d", rv);
+    }
+
+  vec_free (sock_filename);
+  vlib_cli_output (vm, "%U\n", format_vnet_sw_if_index_name, vnet_get_main (),
+		   sw_if_index);
+  return 0;
+}
+
+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 ();
+
+  /* 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 (vnm, sw_if_index);
+	  if (hwif == NULL ||
+	      vhost_user_dev_class.index != hwif->dev_class_index)
+	    return clib_error_return (0, "Not a vhost interface");
+	}
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+  unformat_free (line_input);
+  vhost_user_delete_if (vnm, vm, sw_if_index);
+  return 0;
+}
+
+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;
+  u8 *s = NULL;
+  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->sock_errno = vui->sock_errno;
+      strncpy ((char *) vuid->sock_filename, (char *) vui->sock_filename,
+	       ARRAY_LEN (vuid->sock_filename) - 1);
+
+      s = format (s, "%v%c", hi->name, 0);
+
+      strncpy ((char *) vuid->if_name, (char *) s,
+	       ARRAY_LEN (vuid->if_name) - 1);
+      _vec_len (s) = 0;
+    }
+
+  vec_free (s);
+  vec_free (hw_if_indices);
+
+  *out_vuids = r_vuids;
+
+  return rv;
+}
+
+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;
+  vhost_cpu_t *vhc;
+  vhost_iface_and_queue_t *vhiq;
+  u32 ci;
+
+  int i, j, q;
+  int show_descr = 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_feature
+#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))
+	{
+	  vec_add1 (hw_if_indices, hw_if_index);
+	}
+      else if (unformat (input, "descriptors") || unformat (input, "desc"))
+	show_descr = 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);
+
+  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: %s (ifindex %d)",
+		       hi->name, hw_if_indices[i]);
+
+      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: ");
+      vec_foreach (vhc, vum->cpus)
+      {
+	vec_foreach (vhiq, vhc->rx_queues)
+	{
+	  if (vhiq->vhost_iface_index == vui - vum->vhost_user_interfaces)
+	    vlib_cli_output (vm, "   thread %d on vring %d\n",
+			     vhc - vum->cpus, VHOST_VRING_IDX_TX (vhiq->qid));
+	}
+      }
+
+      vlib_cli_output (vm, " tx placement: %s\n",
+		       vui->use_tx_spinlock ? "spin-lock" : "lock-free");
+
+      vec_foreach_index (ci, vui->per_cpu_tx_qid)
+      {
+	vlib_cli_output (vm, "   thread %d on vring %d\n", ci,
+			 VHOST_VRING_IDX_RX (vui->per_cpu_tx_qid[ci]));
+      }
+
+      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 (q = 0; q < VHOST_VRING_MAX_N; q++)
+	{
+	  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,
+			   "  qsz %d last_avail_idx %d last_used_idx %d\n",
+			   vui->vrings[q].qsz, vui->vrings[q].last_avail_idx,
+			   vui->vrings[q].last_used_idx);
+
+	  if (vui->vrings[q].avail && vui->vrings[q].used)
+	    vlib_cli_output (vm,
+			     "  avail.flags %x avail.idx %d used.flags %x used.idx %d\n",
+			     vui->vrings[q].avail->flags,
+			     vui->vrings[q].avail->idx,
+			     vui->vrings[q].used->flags,
+			     vui->vrings[q].used->idx);
+
+	  int kickfd = UNIX_GET_FD (vui->vrings[q].kickfd_idx);
+	  int callfd = UNIX_GET_FD (vui->vrings[q].callfd_idx);
+	  vlib_cli_output (vm, "  kickfd %d callfd %d errfd %d\n",
+			   kickfd, callfd, vui->vrings[q].errfd);
+
+	  if (show_descr)
+	    {
+	      vlib_cli_output (vm, "\n  descriptor table:\n");
+	      vlib_cli_output (vm,
+			       "   id          addr         len  flags  next      user_addr\n");
+	      vlib_cli_output (vm,
+			       "  ===== ================== ===== ====== ===== ==================\n");
+	      for (j = 0; j < vui->vrings[q].qsz; j++)
+		{
+		  u32 mem_hint = 0;
+		  vlib_cli_output (vm,
+				   "  %-5d 0x%016lx %-5d 0x%04x %-5d 0x%016lx\n",
+				   j, vui->vrings[q].desc[j].addr,
+				   vui->vrings[q].desc[j].len,
+				   vui->vrings[q].desc[j].flags,
+				   vui->vrings[q].desc[j].next,
+				   pointer_to_uword (map_guest_mem
+						     (vui,
+						      vui->vrings[q].desc[j].
+						      addr, &mem_hint)));
+		}
+	    }
+	}
+      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 QEMU/VM and
+ * VPP to manage the vHost interface. If socket does not already exist, VPP will
+ * create the socket.
+ *
+ * - <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.
+ *
+ * - <b>feature-mask <hex></b> - Optional virtio/vhost feature set negotiated at
+ * startup. 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 /tmp/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 /tmp/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>]",
+    .function = vhost_user_connect_command_fn,
+};
+/* *INDENT-ON* */
+
+/*?
+ * Delete a vHost User interface using the interface name or the
+ * software interface index. Use the '<em>show interfaces</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 seperated
+ * 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 /tmp/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    0x0000000000000000 0x00000000000a0000 0x00002aaaaac00000 0x0000000000000000 0x00002aab2b400000
+ *   1     61    0x00000000000c0000 0x000000003ff40000 0x00002aaaaacc0000 0x00000000000c0000 0x00002aababcc0000
+ *
+ *  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]",
+    .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);
+	);
+    }
+}
+
+static clib_error_t *
+vhost_thread_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 worker_thread_index;
+  u32 sw_if_index;
+  u8 del = 0;
+  int rv;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  if (!unformat
+      (line_input, "%U %d", unformat_vnet_sw_interface, vnet_get_main (),
+       &sw_if_index, &worker_thread_index))
+    {
+      unformat_free (line_input);
+      return clib_error_return (0, "unknown input `%U'",
+				format_unformat_error, input);
+    }
+
+  if (unformat (line_input, "del"))
+    del = 1;
+
+  if ((rv =
+       vhost_user_thread_placement (sw_if_index, worker_thread_index, del)))
+    return clib_error_return (0, "vhost_user_thread_placement returned %d",
+			      rv);
+  return 0;
+}
+
+
+/*?
+ * This command is used to move the RX processing for the given
+ * interfaces to the provided thread. If the '<em>del</em>' option is used,
+ * the forced thread assignment is removed and the thread assigment is
+ * reassigned automatically. Use '<em>show vhost-user <interface></em>'
+ * to see the thread assignment.
+ *
+ * @cliexpar
+ * Example of how to move the RX processing for a given interface to a given thread:
+ * @cliexcmd{vhost thread VirtualEthernet0/0/0 1}
+ * Example of how to remove the forced thread assignment for a given interface:
+ * @cliexcmd{vhost thread VirtualEthernet0/0/0 1 del}
+?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (vhost_user_thread_command, static) = {
+    .path = "vhost thread",
+    .short_help = "vhost thread <iface> <worker-index> [del]",
+    .function = vhost_thread_command_fn,
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/devices/virtio/vhost-user.h b/src/vnet/devices/virtio/vhost-user.h
new file mode 100644
index 00000000000..3083b614016
--- /dev/null
+++ b/src/vnet/devices/virtio/vhost-user.h
@@ -0,0 +1,350 @@
+/*
+ * 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__
+/* vhost-user data structures */
+
+#define VHOST_MEMORY_MAX_NREGIONS       8
+#define VHOST_USER_MSG_HDR_SZ           12
+#define VHOST_VRING_MAX_SIZE            32768
+#define VHOST_VRING_MAX_N               16	//8TX + 8RX
+#define VHOST_VRING_IDX_RX(qid)         (2*qid)
+#define VHOST_VRING_IDX_TX(qid)         (2*qid + 1)
+
+#define VIRTQ_DESC_F_NEXT               1
+#define VIRTQ_DESC_F_INDIRECT           4
+#define VHOST_USER_REPLY_MASK       (0x1 << 2)
+
+#define VHOST_USER_PROTOCOL_F_MQ   0
+#define VHOST_USER_PROTOCOL_F_LOG_SHMFD	1
+#define VHOST_VRING_F_LOG 0
+
+#define VHOST_USER_F_PROTOCOL_FEATURES  30
+#define VHOST_USER_PROTOCOL_FEATURES   ((1ULL << VHOST_USER_PROTOCOL_F_MQ) |	\
+					(1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD))
+
+/* If multiqueue is provided by host, then we suppport it. */
+#define VIRTIO_NET_CTRL_MQ   4
+#define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET        0
+#define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        1
+#define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        0x8000
+
+#define VRING_USED_F_NO_NOTIFY  1
+
+#define foreach_virtio_net_feature      \
+ _ (VIRTIO_NET_F_MRG_RXBUF, 15)         \
+ _ (VIRTIO_NET_F_CTRL_VQ, 17)           \
+ _ (VIRTIO_NET_F_GUEST_ANNOUNCE, 21)    \
+ _ (VIRTIO_NET_F_MQ, 22)                \
+ _ (VHOST_F_LOG_ALL, 26)                \
+ _ (VIRTIO_F_ANY_LAYOUT, 27)            \
+ _ (VIRTIO_F_INDIRECT_DESC, 28)         \
+ _ (VHOST_USER_F_PROTOCOL_FEATURES, 30) \
+ _ (VIRTIO_F_VERSION_1, 32)
+
+
+typedef enum
+{
+#define _(f,n) FEAT_##f = (n),
+  foreach_virtio_net_feature
+#undef _
+} virtio_net_feature_t;
+
+int vhost_user_create_if (vnet_main_t * vnm, vlib_main_t * vm,
+			  const char *sock_filename, u8 is_server,
+			  u32 * sw_if_index, u64 feature_mask,
+			  u8 renumber, u32 custom_dev_instance, u8 * hwaddr);
+int vhost_user_modify_if (vnet_main_t * vnm, vlib_main_t * vm,
+			  const char *sock_filename, u8 is_server,
+			  u32 sw_if_index, u64 feature_mask,
+			  u8 renumber, u32 custom_dev_instance);
+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 struct
+{
+  u32 index, num;
+} __attribute ((packed)) vhost_vring_state_t;
+
+typedef struct
+{
+  u32 index, flags;
+  u64 desc_user_addr, used_user_addr, avail_user_addr, log_guest_addr;
+} __attribute ((packed)) vhost_vring_addr_t;
+
+typedef struct vhost_user_log
+{
+  u64 size;
+  u64 offset;
+} __attribute ((packed)) vhost_user_log_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;
+
+// vring_desc I/O buffer descriptor
+typedef struct
+{
+  uint64_t addr;  // packet data buffer address
+  uint32_t len;   // packet data buffer size
+  uint16_t flags; // (see below)
+  uint16_t next;  // optional index next descriptor in chain
+} __attribute ((packed)) vring_desc_t;
+
+typedef struct
+{
+  uint16_t flags;
+  volatile uint16_t idx;
+  uint16_t ring[VHOST_VRING_MAX_SIZE];
+} __attribute ((packed)) vring_avail_t;
+
+typedef struct
+{
+  uint16_t flags;
+  uint16_t idx;
+  struct /* vring_used_elem */
+    {
+      uint32_t id;
+      uint32_t len;
+    } ring[VHOST_VRING_MAX_SIZE];
+} __attribute ((packed)) vring_used_t;
+
+typedef struct
+{
+  u8 flags;
+  u8 gso_type;
+  u16 hdr_len;
+  u16 gso_size;
+  u16 csum_start;
+  u16 csum_offset;
+} __attribute ((packed)) virtio_net_hdr_t;
+
+typedef struct  {
+  virtio_net_hdr_t hdr;
+  u16 num_buffers;
+} __attribute ((packed)) virtio_net_hdr_mrg_rxbuf_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;
+  u16 last_avail_idx;
+  u16 last_used_idx;
+  u16 n_since_last_int;
+  vring_desc_t *desc;
+  vring_avail_t *avail;
+  vring_used_t *used;
+  f64 int_deadline;
+  u8 started;
+  u8 enabled;
+  u8 log_used;
+  //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;
+} vhost_user_vring_t;
+
+typedef struct
+{
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+  u32 is_up;
+  u32 admin_up;
+  u32 unix_server_index;
+  u32 unix_file_index;
+  char sock_filename[256];
+  int sock_errno;
+  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[VHOST_VRING_MAX_N];
+  volatile u32 *vring_locks[VHOST_VRING_MAX_N];
+
+  int virtio_net_hdr_sz;
+  int is_any_layout;
+
+  void *log_base_addr;
+  u64 log_size;
+
+  /* Whether to use spinlock or per_cpu_tx_qid assignment */
+  u8 use_tx_spinlock;
+  u16 *per_cpu_tx_qid;
+
+  /* Vector of workers for this interface */
+  u32 *workers;
+} vhost_user_intf_t;
+
+typedef struct
+{
+  u16 vhost_iface_index;
+  u16 qid;
+} vhost_iface_and_queue_t;
+
+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 **/
+  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
+{
+  vhost_iface_and_queue_t *rx_queues;
+  u32 rx_buffers_len;
+  u32 rx_buffers[VHOST_USER_RX_BUFFERS_N];
+
+  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;
+} vhost_cpu_t;
+
+typedef struct
+{
+  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;
+
+  /** first cpu index */
+  u32 input_cpu_first_index;
+
+  /** total cpu count */
+  u32 input_cpu_count;
+
+  /** Per-CPU data for vhost-user */
+  vhost_cpu_t *cpus;
+
+  /** Pseudo random iterator */
+  u32 random;
+} 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);
+
+// CLI commands to be used from dpdk
+clib_error_t *vhost_user_connect_command_fn (vlib_main_t * vm,
+					     unformat_input_t * input,
+					     vlib_cli_command_t * cmd);
+clib_error_t *vhost_user_delete_command_fn (vlib_main_t * vm,
+					    unformat_input_t * input,
+					    vlib_cli_command_t * cmd);
+clib_error_t *show_vhost_user_command_fn (vlib_main_t * vm,
+					  unformat_input_t * input,
+					  vlib_cli_command_t * cmd);
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/devices/virtio/vhost_user.api b/src/vnet/devices/virtio/vhost_user.api
new file mode 100644
index 00000000000..21e42298361
--- /dev/null
+++ b/src/vnet/devices/virtio/vhost_user.api
@@ -0,0 +1,125 @@
+/*
+ * 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.
+ */
+
+/** \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 mac_address - hardware address to use if 'use_custom_mac' is set
+*/
+define create_vhost_user_if
+{
+  u32 client_index;
+  u32 context;
+  u8 is_server;
+  u8 sock_filename[256];
+  u8 renumber;
+  u32 custom_dev_instance;
+  u8 use_custom_mac;
+  u8 mac_address[6];
+  u8 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
+{
+  u32 context;
+  i32 retval;
+  u32 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
+*/
+define modify_vhost_user_if
+{
+  u32 client_index;
+  u32 context;
+  u32 sw_if_index;
+  u8 is_server;
+  u8 sock_filename[256];
+  u8 renumber;
+  u32 custom_dev_instance;
+};
+
+/** \brief vhost-user interface modify response
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+*/
+define modify_vhost_user_if_reply
+{
+  u32 context;
+  i32 retval;
+};
+
+/** \brief vhost-user interface delete request
+    @param client_index - opaque cookie to identify the sender
+*/
+define delete_vhost_user_if
+{
+  u32 client_index;
+  u32 context;
+  u32 sw_if_index;
+};
+
+/** \brief vhost-user interface delete response
+    @param context - sender context, to match reply w/ request
+    @param retval - return code for the request
+*/
+define delete_vhost_user_if_reply
+{
+  u32 context;
+  i32 retval;
+};
+
+/** \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 - interface features
+    @param is_server - vhost-user server socket
+    @param sock_filename - socket filename
+    @param num_regions - number of used memory regions
+*/
+define sw_interface_vhost_user_details
+{
+  u32 context;
+  u32 sw_if_index;
+  u8 interface_name[64];
+  u32 virtio_net_hdr_sz;
+  u64 features;
+  u8 is_server;
+  u8 sock_filename[256];
+  u32 num_regions;
+  i32 sock_errno;
+};
+
+define sw_interface_vhost_user_dump
+{
+  u32 client_index;
+  u32 context;
+};
+/*
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/devices/virtio/vhost_user_api.c b/src/vnet/devices/virtio/vhost_user_api.c
new file mode 100644
index 00000000000..dd517c26f55
--- /dev/null
+++ b/src/vnet/devices/virtio/vhost_user_api.c
@@ -0,0 +1,262 @@
+/*
+ *------------------------------------------------------------------
+ * 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 <vnet/devices/virtio/vhost-user.h>
+
+#include <vnet/vnet_msg_enum.h>
+
+#define vl_typedefs		/* define message structures */
+#include <vnet/vnet_all_api_h.h>
+#undef vl_typedefs
+
+#define vl_endianfun		/* define message structures */
+#include <vnet/vnet_all_api_h.h>
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+#define vl_printfun
+#include <vnet/vnet_all_api_h.h>
+#undef vl_printfun
+
+#include <vlibapi/api_helper_macros.h>
+
+#define foreach_vpe_api_msg                                             \
+_(CREATE_VHOST_USER_IF, create_vhost_user_if)                           \
+_(MODIFY_VHOST_USER_IF, modify_vhost_user_if)                           \
+_(DELETE_VHOST_USER_IF, delete_vhost_user_if)                           \
+_(SW_INTERFACE_VHOST_USER_DUMP, sw_interface_vhost_user_dump)           \
+_(SW_INTERFACE_VHOST_USER_DETAILS, sw_interface_vhost_user_details)
+
+/*
+ * WARNING: replicated pending api refactor completion
+ */
+static void
+send_sw_interface_flags_deleted (vpe_api_main_t * am,
+				 unix_shared_memory_queue_t * q,
+				 u32 sw_if_index)
+{
+  vl_api_sw_interface_set_flags_t *mp;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (VL_API_SW_INTERFACE_SET_FLAGS);
+  mp->sw_if_index = ntohl (sw_if_index);
+
+  mp->admin_up_down = 0;
+  mp->link_up_down = 0;
+  mp->deleted = 1;
+  vl_msg_api_send_shmem (q, (u8 *) & mp);
+}
+
+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;
+  u32 sw_if_index = (u32) ~ 0;
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  rv = vhost_user_create_if (vnm, vm, (char *) mp->sock_filename,
+			     mp->is_server, &sw_if_index, (u64) ~ 0,
+			     mp->renumber, ntohl (mp->custom_dev_instance),
+			     (mp->use_custom_mac) ? mp->mac_address : NULL);
+
+  /* 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, sw_if_index);
+	}
+    }
+
+  /* *INDENT-OFF* */
+  REPLY_MACRO2(VL_API_CREATE_VHOST_USER_IF_REPLY,
+  ({
+    rmp->sw_if_index = ntohl (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;
+  u32 sw_if_index = ntohl (mp->sw_if_index);
+
+  vnet_main_t *vnm = vnet_get_main ();
+  vlib_main_t *vm = vlib_get_main ();
+
+  rv = vhost_user_modify_if (vnm, vm, (char *) mp->sock_filename,
+			     mp->is_server, sw_if_index, (u64) ~ 0,
+			     mp->renumber, ntohl (mp->custom_dev_instance));
+
+  REPLY_MACRO (VL_API_MODIFY_VHOST_USER_IF_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;
+  vpe_api_main_t *vam = &vpe_api_main;
+  u32 sw_if_index = ntohl (mp->sw_if_index);
+
+  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)
+    {
+      unix_shared_memory_queue_t *q =
+	vl_api_client_index_to_input_queue (mp->client_index);
+      if (!q)
+	return;
+
+      vnet_clear_sw_interface_tag (vnm, sw_if_index);
+      send_sw_interface_flags_deleted (vam, q, sw_if_index);
+    }
+}
+
+static void
+  vl_api_sw_interface_vhost_user_details_t_handler
+  (vl_api_sw_interface_vhost_user_details_t * mp)
+{
+  clib_warning ("BUG");
+}
+
+static void
+send_sw_interface_vhost_user_details (vpe_api_main_t * am,
+				      unix_shared_memory_queue_t * q,
+				      vhost_user_intf_details_t * vui,
+				      u32 context)
+{
+  vl_api_sw_interface_vhost_user_details_t *mp;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (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);
+  mp->features = clib_net_to_host_u64 (vui->features);
+  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_msg_api_send_shmem (q, (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;
+  unix_shared_memory_queue_t *q;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  rv = vhost_user_dump_ifs (vnm, vm, &ifaces);
+  if (rv)
+    return;
+
+  vec_foreach (vuid, ifaces)
+  {
+    send_sw_interface_vhost_user_details (am, q, vuid, mp->context);
+  }
+  vec_free (ifaces);
+}
+
+/*
+ * vhost-user_api_hookup
+ * Add vpe's API message handlers to the table.
+ * vlib has alread mapped shared memory and
+ * added the client registration handlers.
+ * See .../vlib-api/vlibmemory/memclnt_vlib.c:memclnt_process()
+ */
+#define vl_msg_name_crc_list
+#include <vnet/vnet_all_api_h.h>
+#undef vl_msg_name_crc_list
+
+static void
+setup_message_id_table (api_main_t * am)
+{
+#define _(id,n,crc) vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id);
+  foreach_vl_msg_name_crc_vhost_user;
+#undef _
+}
+
+static clib_error_t *
+vhost_user_api_hookup (vlib_main_t * vm)
+{
+  api_main_t *am = &api_main;
+
+#define _(N,n)                                                  \
+    vl_msg_api_set_handlers(VL_API_##N, #n,                     \
+                           vl_api_##n##_t_handler,              \
+                           vl_noop_handler,                     \
+                           vl_api_##n##_t_endian,               \
+                           vl_api_##n##_t_print,                \
+                           sizeof(vl_api_##n##_t), 1);
+  foreach_vpe_api_msg;
+#undef _
+
+  /*
+   * Set up the (msg_name, crc, message-id) table
+   */
+  setup_message_id_table (am);
+
+  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:
+ */