[PULL 12/31] vhost-user-blk: fix blkcfg->num_queues endianness

[Kevin Wolf <kwolf@redhat.com>]

From: Stefan Hajnoczi <stefanha@redhat.com>

Treat the num_queues field as virtio-endian. On big-endian hosts the
vhost-user-blk num_queues field was in the wrong endianness.

Move the blkcfg.num_queues store operation from realize to
vhost_user_blk_update_config() so feature negotiation has finished and
we know the endianness of the device. VIRTIO 1.0 devices are
little-endian, but in case someone wants to use legacy VIRTIO we support
all endianness cases.

Cc: qemu-stable@nongnu.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20210223144653.811468-2-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/block/vhost-user-blk.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index da4fbf9084..b870a50e6b 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -54,6 +54,9 @@ static void vhost_user_blk_update_config(VirtIODevice *vdev, uint8_t *config)
 {
     VHostUserBlk *s = VHOST_USER_BLK(vdev);
 
+    /* Our num_queues overrides the device backend */
+    virtio_stw_p(vdev, &s->blkcfg.num_queues, s->num_queues);
+
     memcpy(config, &s->blkcfg, sizeof(struct virtio_blk_config));
 }
 
@@ -491,10 +494,6 @@ reconnect:
         goto reconnect;
     }
 
-    if (s->blkcfg.num_queues != s->num_queues) {
-        s->blkcfg.num_queues = s->num_queues;
-    }
-
     return;
 
 virtio_err:
-- 
2.29.2