virtio: fast TAP interfaces with vhost-net backend

Change-Id: Ided667356d5c6fb9648eb34685aabd6b16a598b7
Signed-off-by: Damjan Marion <damarion@cisco.com>
Signed-off-by: Steven Luong <sluong@cisco.com>

1 files changed, 302 insertions, 0 deletions

diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
new file mode 100644
index 00000000000..f746ada7326
--- /dev/null
+++ b/src/vnet/devices/virtio/node.c
@@ -0,0 +1,302 @@
+/*
+ *------------------------------------------------------------------
+ * 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 <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+#include <sys/ioctl.h>
+#include <linux/virtio_net.h>
+#include <linux/vhost.h>
+#include <sys/eventfd.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/devices.h>
+#include <vnet/feature/feature.h>
+#include <vnet/devices/virtio/virtio.h>
+
+
+#define foreach_virtio_input_error \
+  _(UNKNOWN, "unknown")
+
+typedef enum
+{
+#define _(f,s) TAP_INPUT_ERROR_##f,
+  foreach_virtio_input_error
+#undef _
+    TAP_INPUT_N_ERROR,
+} virtio_input_error_t;
+
+static char *virtio_input_error_strings[] = {
+#define _(n,s) s,
+  foreach_virtio_input_error
+#undef _
+};
+
+typedef struct
+{
+  u32 next_index;
+  u32 hw_if_index;
+  u16 ring;
+  u16 len;
+  struct virtio_net_hdr_v1 hdr;
+} virtio_input_trace_t;
+
+static u8 *
+format_virtio_input_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  virtio_input_trace_t *t = va_arg (*args, virtio_input_trace_t *);
+  u32 indent = format_get_indent (s);
+
+  s = format (s, "virtio: hw_if_index %d next-index %d vring %u len %u",
+	      t->hw_if_index, t->next_index, t->ring, t->len);
+  s = format (s, "\n%Uhdr: flags 0x%02x gso_type 0x%02x hdr_len %u "
+	      "gso_size %u csum_start %u csum_offset %u num_buffers %u",
+	      format_white_space, indent + 2,
+	      t->hdr.flags, t->hdr.gso_type, t->hdr.hdr_len, t->hdr.gso_size,
+	      t->hdr.csum_start, t->hdr.csum_offset, t->hdr.num_buffers);
+  return s;
+}
+
+static_always_inline void
+virtio_refill_vring (vlib_main_t * vm, virtio_vring_t * vring)
+{
+  const int hdr_sz = sizeof (struct virtio_net_hdr_v1);
+  u16 used, next, avail, n_slots, n_alloc;
+  u16 sz = vring->size;
+  u16 mask = sz - 1;
+  int i;
+
+  used = vring->desc_in_use;
+
+  if (sz - used < sz / 8)
+    return;
+
+  n_slots = sz - used;
+  next = vring->desc_next;
+  avail = vring->avail->idx;
+  n_alloc = vlib_buffer_alloc (vm, &vring->buffers[next], n_slots);
+
+  if (PREDICT_FALSE (n_alloc < n_slots))
+    n_slots = n_alloc;
+
+  i = next + n_slots - sz;
+  if (PREDICT_FALSE (i > 0))
+    clib_memcpy (vring->buffers, &vring->buffers[sz], i * sizeof (u32));
+
+  while (n_slots)
+    {
+      struct vring_desc *d = &vring->desc[next];;
+      vlib_buffer_t *b = vlib_get_buffer (vm, vring->buffers[next]);
+      d->addr = pointer_to_uword (vlib_buffer_get_current (b)) - hdr_sz;
+      d->len = VLIB_BUFFER_DATA_SIZE + hdr_sz;
+      d->flags = VRING_DESC_F_WRITE;
+      vring->avail->ring[avail & mask] = next;
+      avail++;
+      next = (next + 1) & mask;
+      n_slots--;
+      used++;
+    }
+  CLIB_MEMORY_STORE_BARRIER ();
+  vring->avail->idx = avail;
+  vring->desc_next = next;
+  vring->desc_in_use = used;
+
+  if ((vring->used->flags & VIRTIO_RING_FLAG_MASK_INT) == 0)
+    {
+      u64 b = 1;
+      CLIB_UNUSED (int r) = write (vring->kick_fd, &b, sizeof (b));
+    }
+}
+
+static_always_inline uword
+virtio_device_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
+			    vlib_frame_t * frame, virtio_if_t * vif, u16 qid)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 thread_index = vlib_get_thread_index ();
+  uword n_trace = vlib_get_trace_count (vm, node);
+  virtio_vring_t *vring = vec_elt_at_index (vif->vrings, 0);
+  u32 next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
+  const int hdr_sz = sizeof (struct virtio_net_hdr_v1);
+  u32 *to_next = 0;
+  u32 n_rx_packets = 0;
+  u32 n_rx_bytes = 0;
+  u16 mask = vring->size - 1;
+  u16 last = vring->last_used_idx;
+  u16 n_left = vring->used->idx - last;
+
+  if (n_left == 0)
+    goto refill;
+
+  while (n_left)
+    {
+      u32 n_left_to_next;
+      u32 next0 = next_index;
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      while (n_left && n_left_to_next)
+	{
+	  u16 num_buffers;
+	  struct vring_used_elem *e = &vring->used->ring[last & mask];
+	  struct virtio_net_hdr_v1 *hdr;
+	  u16 slot = e->id;
+	  u16 len = e->len - hdr_sz;
+	  u32 bi0 = vring->buffers[slot];
+	  vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
+	  hdr = vlib_buffer_get_current (b0) - hdr_sz;
+	  num_buffers = hdr->num_buffers;
+
+	  b0->current_data = 0;
+	  b0->current_length = len;
+	  b0->total_length_not_including_first_buffer = 0;
+	  b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
+	  vnet_buffer (b0)->sw_if_index[VLIB_RX] = vif->sw_if_index;
+	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+
+	  /* if multisegment packet */
+	  if (PREDICT_FALSE (num_buffers > 1))
+	    {
+	      vlib_buffer_t *pb, *cb;
+	      pb = b0;
+	      while (num_buffers > 1)
+		{
+		  last++;
+		  e = &vring->used->ring[last & mask];
+		  u32 cbi = vring->buffers[e->id];
+		  cb = vlib_get_buffer (vm, cbi);
+
+		  /* current buffer */
+		  cb->current_data = -hdr_sz;
+		  cb->current_length = e->len;
+
+		  /* previous buffer */
+		  pb->next_buffer = cbi;
+		  pb->flags |= VLIB_BUFFER_NEXT_PRESENT;
+
+		  /* first buffer */
+		  b0->total_length_not_including_first_buffer += e->len;
+
+		  pb = cb;
+		  vring->desc_in_use--;
+		  num_buffers--;
+		  n_left--;
+		}
+	    }
+
+	  if (PREDICT_FALSE (vif->per_interface_next_index != ~0))
+	    next0 = vif->per_interface_next_index;
+	  else
+	    /* redirect if feature path enabled */
+	    vnet_feature_start_device_input_x1 (vif->sw_if_index, &next0, b0);
+	  /* trace */
+	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
+
+	  if (PREDICT_FALSE (n_trace > 0))
+	    {
+	      virtio_input_trace_t *tr;
+	      vlib_trace_buffer (vm, node, next0, b0,
+				 /* follow_chain */ 0);
+	      vlib_set_trace_count (vm, node, --n_trace);
+	      tr = vlib_add_trace (vm, node, b0, sizeof (*tr));
+	      tr->next_index = next0;
+	      tr->hw_if_index = vif->hw_if_index;
+	      tr->len = len;
+	      clib_memcpy (&tr->hdr, hdr, hdr_sz);
+	    }
+
+	  /* enqueue buffer */
+	  to_next[0] = bi0;
+	  vring->desc_in_use--;
+	  to_next += 1;
+	  n_left_to_next--;
+	  n_left--;
+	  last++;
+
+	  /* enqueue */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, bi0, next0);
+
+	  /* next packet */
+	  n_rx_packets++;
+	  n_rx_bytes += len;
+	}
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+  vring->last_used_idx = last;
+
+  vlib_increment_combined_counter (vnm->interface_main.combined_sw_if_counters
+				   + VNET_INTERFACE_COUNTER_RX, thread_index,
+				   vif->hw_if_index, n_rx_packets,
+				   n_rx_bytes);
+
+refill:
+  virtio_refill_vring (vm, vring);
+
+  return n_rx_packets;
+}
+
+static uword
+virtio_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
+		 vlib_frame_t * frame)
+{
+  u32 n_rx = 0;
+  virtio_main_t *nm = &virtio_main;
+  vnet_device_input_runtime_t *rt = (void *) node->runtime_data;
+  vnet_device_and_queue_t *dq;
+
+  foreach_device_and_queue (dq, rt->devices_and_queues)
+  {
+    virtio_if_t *mif;
+    mif = vec_elt_at_index (nm->interfaces, dq->dev_instance);
+    if (mif->flags & VIRTIO_IF_FLAG_ADMIN_UP)
+      {
+	n_rx += virtio_device_input_inline (vm, node, frame, mif,
+					    dq->queue_id);
+      }
+  }
+
+  return n_rx;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (virtio_input_node) = {
+  .function = virtio_input_fn,
+  .name = "virtio-input",
+  .sibling_of = "device-input",
+  .format_trace = format_virtio_input_trace,
+  .type = VLIB_NODE_TYPE_INPUT,
+  .state = VLIB_NODE_STATE_INTERRUPT,
+  .n_errors = TAP_INPUT_N_ERROR,
+  .error_strings = virtio_input_error_strings,
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (virtio_input_node, virtio_input_fn)
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */