virtio_balloon: enable VQs early on restore

virtio spec requires drivers to set DRIVER_OK before using VQs.
This is set automatically after resume returns, virtio balloon
violated this rule by adding bufs, which causes the VQ to be used
directly within restore.

To fix, call virtio_device_ready before using VQ.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 25ebe8eecdb7..f4a28af4865e 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -538,6 +538,8 @@ static int virtballoon_restore(struct virtio_device *vdev)
         if (ret)
                 return ret;
 
+        virtio_device_ready(vdev);
+
         fill_balloon(vb, towards_target(vb));
         update_balloon_size(vb);
         return 0;