vhost-net: save & restore vhost-user acked features

The initial vhost-user connection sets the features to be negotiated
with the driver. Renegotiation isn't possible without device reset.

To handle reconnection of vhost-user backend, ensure the same set of
features are provided, and reuse already acked features.

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, 10 insertions, 0 deletions

diff --git a/net/vhost-user.c b/net/vhost-user.c
index 41ddb4b..d72ce9b 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -23,6 +23,7 @@ typedef struct VhostUserState {
     CharDriverState *chr;
     VHostNetState *vhost_net;
     int watch;
+    uint64_t acked_features;
 } VhostUserState;
 
 typedef struct VhostUserChardevProps {
@@ -37,6 +38,13 @@ VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
     return s->vhost_net;
 }
 
+uint64_t vhost_user_get_acked_features(NetClientState *nc)
+{
+    VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
+    assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+    return s->acked_features;
+}
+
 static int vhost_user_running(VhostUserState *s)
 {
     return (s->vhost_net) ? 1 : 0;
@@ -56,6 +64,8 @@ static void vhost_user_stop(int queues, NetClientState *ncs[])
         }
 
         if (s->vhost_net) {
+            /* save acked features */
+            s->acked_features = vhost_net_get_acked_features(s->vhost_net);
             vhost_net_cleanup(s->vhost_net);
             s->vhost_net = NULL;
         }