[qemu-xen stable-4.14] virtio-balloon: fix free page hinting check on unrealize

[patchbot@xxxxxxx]

commit 945d9273c8234dcc2f301059fe294df5e722b055
Author:     David Hildenbrand <david@xxxxxxxxxx>
AuthorDate: Wed May 20 12:04:38 2020 +0200
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Aug 24 18:56:15 2020 -0500

    virtio-balloon: fix free page hinting check on unrealize
    
    Checking against guest features is wrong. We allocated data structures
    based on host features. We can rely on "free_page_bh" as an indicator
    whether to un-do stuff instead.
    
    Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
    Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
    Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
    Cc: qemu-stable@xxxxxxxxxx
    Cc: Wei Wang <wei.w.wang@xxxxxxxxx>
    Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
    Cc: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
    Cc: Alexander Duyck <alexander.duyck@xxxxxxxxx>
    Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
    Message-Id: <20200520100439.19872-3-david@xxxxxxxxxx>
    Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    (cherry picked from commit 49b01711b8eb3796c6904c7f85d2431572cfe54f)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 hw/virtio/virtio-balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index ef499e1b3b..3e3b5ff0f8 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -818,7 +818,7 @@ static void virtio_balloon_device_unrealize(DeviceState 
*dev, Error **errp)
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOBalloon *s = VIRTIO_BALLOON(dev);
 
-    if (virtio_balloon_free_page_support(s)) {
+    if (s->free_page_bh) {
         qemu_bh_delete(s->free_page_bh);
         virtio_balloon_free_page_stop(s);
         precopy_remove_notifier(&s->free_page_report_notify);
--
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