vhost-net: save & restore vring enable state

A driver may change the vring enable state at run time but vhost-user
backend may not be present (a contrived example is when the backend is
disconnected and the device is reconfigured after driver rebinding)

Restore the vring state when the vhost-user backend is started, so it
can process the ring.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Victor Kaplansky <victork@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/net.h b/include/net/net.h
index a69e382..a5c5095 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -99,6 +99,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
+    int vring_enable;
     QTAILQ_HEAD(NetFilterHead, NetFilterState) filters;
 };