tap: add check for vhost-net backend

Type: feature

Change-Id: I402f4c88dee70fbb0b3b61dc4e0a4034d24d8b56
Signed-off-by: Damjan Marion <damarion@cisco.com>

diff --git a/src/vnet/devices/tap/tap.c b/src/vnet/devices/tap/tap.c
index bc790ad..a1d5981 100644 (file)
--- a/src/vnet/devices/tap/tap.c
+++ b/src/vnet/devices/tap/tap.c
@@ -94,6 +94,7 @@ tap_create_if (vlib_main_t * vm, tap_create_if_args_t * args)
   struct vhost_memory *vhost_mem = 0;
   virtio_if_t *vif = 0;
   clib_error_t *err = 0;
+  unsigned int tap_features;
   int fd = -1;
   char *host_if_name = 0;
 
@@ -173,6 +174,14 @@ tap_create_if (vlib_main_t * vm, tap_create_if_args_t * args)
       goto error;
     }
 
+  _IOCTL (vif->tap_fd, TUNGETFEATURES, &tap_features);
+  if ((tap_features & IFF_VNET_HDR) == 0)
+    {
+      args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
+      args->error = clib_error_return (0, "vhost-net backend not available");
+      goto error;
+    }
+
   ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR;
   _IOCTL (vif->tap_fd, TUNSETIFF, (void *) &ifr);
   vif->ifindex = if_nametoindex (ifr.ifr_ifrn.ifrn_name);