vhost: add vhost_net_set_backend()

Not all vhost-user backends support ops->vhost_net_set_backend(). It is
a nicer to provide an assert/error than to crash trying to
call. Furthermore, it improves a bit the code by hiding vhost_ops
details.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2d0d1d1ba9..b0e8ecce60 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1369,3 +1369,13 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
     vhost_log_put(hdev, true);
     hdev->started = false;
 }
+
+int vhost_net_set_backend(struct vhost_dev *hdev,
+                          struct vhost_vring_file *file)
+{
+    if (hdev->vhost_ops->vhost_net_set_backend) {
+        return hdev->vhost_ops->vhost_net_set_backend(hdev, file);
+    }
+
+    return -1;
+}