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, 328 insertions, 0 deletions

diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c
new file mode 100644
index 00000000000..275a3c74990
--- /dev/null
+++ b/src/vnet/devices/virtio/device.c
@@ -0,0 +1,328 @@
+/*
+ *------------------------------------------------------------------
+ * 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 <linux/virtio_net.h>
+#include <linux/vhost.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/devices/virtio/virtio.h>
+
+#define foreach_virtio_tx_func_error	       \
+_(NO_FREE_SLOTS, "no free tx slots")           \
+_(TRUNC_PACKET, "packet > buffer size -- truncated in tx ring") \
+_(PENDING_MSGS, "pending msgs in tx ring") \
+_(NO_TX_QUEUES, "no tx queues")
+
+typedef enum
+{
+#define _(f,s) TAP_TX_ERROR_##f,
+  foreach_virtio_tx_func_error
+#undef _
+    TAP_TX_N_ERROR,
+} virtio_tx_func_error_t;
+
+static char *virtio_tx_func_error_strings[] = {
+#define _(n,s) s,
+  foreach_virtio_tx_func_error
+#undef _
+};
+
+u8 *
+format_virtio_device_name (u8 * s, va_list * args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  virtio_main_t *mm = &virtio_main;
+  virtio_if_t *vif = pool_elt_at_index (mm->interfaces, dev_instance);
+
+  if (vif->type == VIRTIO_IF_TYPE_TAP)
+    {
+      s = format (s, "tap-%s", vif->name);
+    }
+  else
+    s = format (s, "virtio%lu", vif->dev_instance);
+
+  return s;
+}
+
+static u8 *
+format_virtio_device (u8 * s, va_list * args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  int verbose = va_arg (*args, int);
+  u32 indent = format_get_indent (s);
+
+  s = format (s, "VIRTIO interface");
+  if (verbose)
+    {
+      s = format (s, "\n%U instance %u", format_white_space, indent + 2,
+		  dev_instance);
+    }
+  return s;
+}
+
+static u8 *
+format_virtio_tx_trace (u8 * s, va_list * args)
+{
+  s = format (s, "Unimplemented...");
+  return s;
+}
+
+static_always_inline void
+virtio_free_used_desc (vlib_main_t * vm, virtio_vring_t * vring)
+{
+  u16 used = vring->desc_in_use;
+  u16 sz = vring->size;
+  u16 mask = sz - 1;
+  u16 last = vring->last_used_idx;
+  u16 n_left = vring->used->idx - last;
+
+  if (n_left == 0)
+    return;
+
+  while (n_left)
+    {
+      struct vring_used_elem *e = &vring->used->ring[last & mask];
+      u16 slot = e->id;
+      struct vring_desc *d = &vring->desc[slot];
+
+      if (PREDICT_FALSE (d->flags & VRING_DESC_F_INDIRECT))
+	{
+	  d = uword_to_pointer (d->addr, struct vring_desc *);
+	  vec_free (d);
+	}
+
+      vlib_buffer_free (vm, &vring->buffers[slot], 1);
+      used--;
+      last++;
+      n_left--;
+    }
+  vring->desc_in_use = used;
+  vring->last_used_idx = last;
+}
+
+static_always_inline u16
+add_buffer_to_slot (vlib_main_t * vm, virtio_vring_t * vring, u32 bi,
+		    u16 avail, u16 next, u16 mask)
+{
+  u16 n_added = 0;
+  const int hdr_sz = sizeof (struct virtio_net_hdr_v1);
+  struct vring_desc *d;
+  d = &vring->desc[next];
+  vlib_buffer_t *b = vlib_get_buffer (vm, bi);
+
+  if (PREDICT_TRUE ((b->flags & VLIB_BUFFER_NEXT_PRESENT) == 0))
+    {
+      d->addr = pointer_to_uword (vlib_buffer_get_current (b)) - hdr_sz;
+      d->len = b->current_length + hdr_sz;
+      d->flags = 0;
+    }
+  else
+    {
+      struct vring_desc *id, *descs = 0;
+
+      /* first buffer in chain */
+      vec_add2_aligned (descs, id, 1, CLIB_CACHE_LINE_BYTES);
+      id->addr = pointer_to_uword (vlib_buffer_get_current (b)) - hdr_sz;
+      id->len = b->current_length + hdr_sz;
+
+      while (b->flags & VLIB_BUFFER_NEXT_PRESENT)
+	{
+	  id->flags = VRING_DESC_F_NEXT;
+	  id->next = vec_len (descs);
+	  vec_add2_aligned (descs, id, 1, CLIB_CACHE_LINE_BYTES);
+	  b = vlib_get_buffer (vm, b->next_buffer);
+	  id->addr = pointer_to_uword (vlib_buffer_get_current (b));
+	  id->len = b->current_length;
+	}
+
+      d->addr = pointer_to_uword (descs);
+      d->len = vec_len (descs) * sizeof (struct vring_desc);
+      d->flags = VRING_DESC_F_INDIRECT;
+    }
+  vring->buffers[next] = bi;
+  vring->avail->ring[avail & mask] = next;
+  n_added++;
+  return n_added;
+}
+
+
+static_always_inline uword
+virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
+			    vlib_frame_t * frame, virtio_if_t * vif)
+{
+  u8 qid = 0;
+  u16 n_left = frame->n_vectors;
+  virtio_vring_t *vring = vec_elt_at_index (vif->vrings, (qid << 1) + 1);
+  u16 used, next, avail;
+  u16 sz = vring->size;
+  u16 mask = sz - 1;
+  u32 *buffers = vlib_frame_args (frame);
+
+  /* free consumed buffers */
+  virtio_free_used_desc (vm, vring);
+
+  used = vring->desc_in_use;
+  next = vring->desc_next;
+  avail = vring->avail->idx;
+
+  while (n_left && used < sz)
+    {
+      u16 n_added;
+      n_added = add_buffer_to_slot (vm, vring, buffers[0], avail, next, mask);
+      avail += n_added;
+      next = (next + n_added) & mask;
+      used += n_added;
+      buffers++;
+      n_left--;
+    }
+
+  if (n_left != frame->n_vectors)
+    {
+      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 x = 1;
+	  CLIB_UNUSED (int r) = write (vring->kick_fd, &x, sizeof (x));
+	}
+    }
+
+
+  if (n_left)
+    {
+      vlib_error_count (vm, node->node_index, TAP_TX_ERROR_NO_FREE_SLOTS,
+			n_left);
+      vlib_buffer_free (vm, buffers, n_left);
+    }
+
+  return frame->n_vectors - n_left;
+}
+
+static uword
+virtio_interface_tx (vlib_main_t * vm,
+		     vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  virtio_main_t *nm = &virtio_main;
+  vnet_interface_output_runtime_t *rund = (void *) node->runtime_data;
+  virtio_if_t *vif = pool_elt_at_index (nm->interfaces, rund->dev_instance);
+
+  return virtio_interface_tx_inline (vm, node, frame, vif);
+}
+
+static void
+virtio_set_interface_next_node (vnet_main_t * vnm, u32 hw_if_index,
+				u32 node_index)
+{
+  virtio_main_t *apm = &virtio_main;
+  vnet_hw_interface_t *hw = vnet_get_hw_interface (vnm, hw_if_index);
+  virtio_if_t *vif = pool_elt_at_index (apm->interfaces, hw->dev_instance);
+
+  /* Shut off redirection */
+  if (node_index == ~0)
+    {
+      vif->per_interface_next_index = node_index;
+      return;
+    }
+
+  vif->per_interface_next_index =
+    vlib_node_add_next (vlib_get_main (), virtio_input_node.index,
+			node_index);
+}
+
+static void
+virtio_clear_hw_interface_counters (u32 instance)
+{
+  /* Nothing for now */
+}
+
+static clib_error_t *
+virtio_interface_rx_mode_change (vnet_main_t * vnm, u32 hw_if_index, u32 qid,
+				 vnet_hw_interface_rx_mode mode)
+{
+  virtio_main_t *mm = &virtio_main;
+  vnet_hw_interface_t *hw = vnet_get_hw_interface (vnm, hw_if_index);
+  virtio_if_t *vif = pool_elt_at_index (mm->interfaces, hw->dev_instance);
+  virtio_vring_t *vring = vec_elt_at_index (vif->vrings, qid);
+
+  if (mode == VNET_HW_INTERFACE_RX_MODE_POLLING)
+    vring->avail->flags |= VIRTIO_RING_FLAG_MASK_INT;
+  else
+    vring->avail->flags &= ~VIRTIO_RING_FLAG_MASK_INT;
+
+  return 0;
+}
+
+static clib_error_t *
+virtio_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index, u32 flags)
+{
+  virtio_main_t *mm = &virtio_main;
+  vnet_hw_interface_t *hw = vnet_get_hw_interface (vnm, hw_if_index);
+  virtio_if_t *vif = pool_elt_at_index (mm->interfaces, hw->dev_instance);
+  static clib_error_t *error = 0;
+
+  if (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
+    vif->flags |= VIRTIO_IF_FLAG_ADMIN_UP;
+  else
+    vif->flags &= ~VIRTIO_IF_FLAG_ADMIN_UP;
+
+  return error;
+  return 0;
+}
+
+static clib_error_t *
+virtio_subif_add_del_function (vnet_main_t * vnm,
+			       u32 hw_if_index,
+			       struct vnet_sw_interface_t *st, int is_add)
+{
+  /* Nothing for now */
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VNET_DEVICE_CLASS (virtio_device_class) = {
+  .name = "virtio",
+  .tx_function = virtio_interface_tx,
+  .format_device_name = format_virtio_device_name,
+  .format_device = format_virtio_device,
+  .format_tx_trace = format_virtio_tx_trace,
+  .tx_function_n_errors = TAP_TX_N_ERROR,
+  .tx_function_error_strings = virtio_tx_func_error_strings,
+  .rx_redirect_to_node = virtio_set_interface_next_node,
+  .clear_counters = virtio_clear_hw_interface_counters,
+  .admin_up_down_function = virtio_interface_admin_up_down,
+  .subif_add_del_function = virtio_subif_add_del_function,
+  .rx_mode_change_function = virtio_interface_rx_mode_change,
+};
+
+VLIB_DEVICE_TX_FUNCTION_MULTIARCH(virtio_device_class,
+				  virtio_interface_tx)
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */