If the avail ring index is bogus virtqueue_num_heads() must return
-EINVAL.
The only caller is virtqueue_get_avail_bytes(). Return saying no bytes
are available when virtqueue_num_heads() fails.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>