We call tap_enable() even if for multiqueue is not enabled. This is
wrong since it should be used for multiqueue codes to enable a
disabled queue. Fixing this by only calling this when multiqueue is
used.

Fixes: 16dbaf905b72 ("tap: support enabling or disabling a queue")
Reported-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
Tested-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index c321680..7d091c9 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -510,6 +510,10 @@ static int peer_attach(VirtIONet *n, int index)
         return 0;
     }
 
+    if (n->max_queues == 1) {
+        return 0;
+    }
+
     return tap_enable(nc->peer);
 }
 
-- 
2.7.4