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, 159 insertions, 0 deletions

diff --git a/src/vnet/devices/virtio/virtio.c b/src/vnet/devices/virtio/virtio.c
new file mode 100644
index 00000000000..63ca6011a9e
--- /dev/null
+++ b/src/vnet/devices/virtio/virtio.c
@@ -0,0 +1,159 @@
+/*
+ *------------------------------------------------------------------
+ * Copyright (c) 2017 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/virtio/virtio.h>
+
+virtio_main_t virtio_main;
+
+#define _IOCTL(fd,a,...) \
+  if (ioctl (fd, a, __VA_ARGS__) < 0) \
+    { \
+      err = clib_error_return_unix (0, "ioctl(" #a ")"); \
+      goto error; \
+    }
+
+static clib_error_t *
+call_read_ready (clib_file_t * uf)
+{
+  virtio_main_t *nm = &virtio_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  u16 qid = uf->private_data & 0xFFFF;
+  virtio_if_t *vif =
+    vec_elt_at_index (nm->interfaces, uf->private_data >> 16);
+  u64 b;
+
+  CLIB_UNUSED (ssize_t size) = read (uf->file_descriptor, &b, sizeof (b));
+  if ((qid & 1) == 0)
+    vnet_device_input_set_interrupt_pending (vnm, vif->hw_if_index, qid);
+
+  return 0;
+}
+
+
+clib_error_t *
+virtio_vring_init (vlib_main_t * vm, virtio_if_t * vif, u16 idx, u16 sz)
+{
+  clib_error_t *err = 0;
+  virtio_vring_t *vring;
+  struct vhost_vring_state state;
+  struct vhost_vring_addr addr;
+  struct vhost_vring_file file;
+  clib_file_t t = { 0 };
+  int i;
+
+  if (!is_pow2 (sz))
+    return clib_error_return (0, "ring size must be power of 2");
+
+  if (sz > 32768)
+    return clib_error_return (0, "ring size must be 32768 or lower");
+
+  if (sz == 0)
+    sz = 256;
+
+  vec_validate_aligned (vif->vrings, idx, CLIB_CACHE_LINE_BYTES);
+  vring = vec_elt_at_index (vif->vrings, idx);
+
+  i = sizeof (struct vring_desc) * sz;
+  i = round_pow2 (i, CLIB_CACHE_LINE_BYTES);
+  vring->desc = clib_mem_alloc_aligned (i, CLIB_CACHE_LINE_BYTES);
+  memset (vring->desc, 0, i);
+
+  i = sizeof (struct vring_avail) + sz * sizeof (vring->avail->ring[0]);
+  i = round_pow2 (i, CLIB_CACHE_LINE_BYTES);
+  vring->avail = clib_mem_alloc_aligned (i, CLIB_CACHE_LINE_BYTES);
+  memset (vring->avail, 0, i);
+  // tell kernel that we don't need interrupt
+  vring->avail->flags = VIRTIO_RING_FLAG_MASK_INT;
+
+  i = sizeof (struct vring_used) + sz * sizeof (struct vring_used_elem);
+  i = round_pow2 (i, CLIB_CACHE_LINE_BYTES);
+  vring->used = clib_mem_alloc_aligned (i, CLIB_CACHE_LINE_BYTES);
+  memset (vring->used, 0, i);
+
+  ASSERT (vring->buffers == 0);
+  vec_validate_aligned (vring->buffers, sz * 2, CLIB_CACHE_LINE_BYTES);
+
+  vring->size = sz;
+  vring->call_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
+  vring->kick_fd = eventfd (0, EFD_CLOEXEC);
+
+  t.read_function = call_read_ready;
+  t.file_descriptor = vring->call_fd;
+  t.private_data = vif->dev_instance << 16 | idx;
+  vring->call_file_index = clib_file_add (&file_main, &t);
+
+  state.index = idx;
+  state.num = sz;
+  _IOCTL (vif->fd, VHOST_SET_VRING_NUM, &state);
+
+  addr.index = idx;
+  addr.flags = 0;
+  addr.desc_user_addr = pointer_to_uword (vring->desc);
+  addr.avail_user_addr = pointer_to_uword (vring->avail);
+  addr.used_user_addr = pointer_to_uword (vring->used);
+  _IOCTL (vif->fd, VHOST_SET_VRING_ADDR, &addr);
+
+  file.index = idx;
+  file.fd = vring->kick_fd;
+  _IOCTL (vif->fd, VHOST_SET_VRING_KICK, &file);
+  file.fd = vring->call_fd;
+  _IOCTL (vif->fd, VHOST_SET_VRING_CALL, &file);
+  file.fd = vif->tap_fd;
+  _IOCTL (vif->fd, VHOST_NET_SET_BACKEND, &file);
+
+error:
+  return err;
+}
+
+clib_error_t *
+virtio_vring_free (virtio_if_t * vif, u32 idx)
+{
+  //TODO free buffers and indirect descriptor allocs
+  virtio_vring_t *vring = vec_elt_at_index (vif->vrings, idx);
+  if (vring->desc)
+    clib_mem_free (vring->desc);
+  if (vring->avail)
+    clib_mem_free (vring->avail);
+  if (vring->used)
+    clib_mem_free (vring->used);
+  clib_file_del_by_index (&file_main, vring->call_file_index);
+  close (vring->kick_fd);
+  close (vring->call_fd);
+  vec_free (vring->buffers);
+  return 0;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */