virtio_blk: enable VQs early on restore

virtio spec requires drivers to set DRIVER_OK before using VQs.
This is set automatically after restore returns, virtio block violated
this rule on restore by restarting queues, which might in theory
cause the VQ to be used directly within restore.

To fix, call virtio_device_ready before using starting queues.

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

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 34ec273b1d46..930fee886917 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -804,10 +804,13 @@ static int virtblk_restore(struct virtio_device *vdev)
         int ret;
 
         ret = init_vq(vdev->priv);
-        if (!ret)
-                blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
+        if (ret)
+                return ret;
+
+        virtio_device_ready(vdev);
 
-        return ret;
+        blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
+        return 0;
 }
 #endif