[Qemu-devel] [PATCH-for-4.1 v2 3/3] virtio-balloon: reset pbp on device resets

[David Hildenbrand <david@redhat.com>]

When a guest reboots (ordinary reboots, but also via kexec), it will
happily reuse any system memory, including previously inflated memory.

We could have tracking data for a pbp (PartiallyBalloonedPage). It could
happen that a new inflation request from the guest will result in a
discard of such a pbp, although the guest is (again) reusing some
memory.

We should reset the pbp on any device resets.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE <
                     host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/virtio/virtio-balloon.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 84d01bceb3..9de3c030bf 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -847,6 +847,7 @@ static void virtio_balloon_device_reset(VirtIODevice *vdev)
     if (virtio_balloon_free_page_support(s)) {
         virtio_balloon_free_page_stop(s);
     }
+    virtio_balloon_reset_pbp(s);
 
     if (s->stats_vq_elem != NULL) {
         virtqueue_unpop(s->svq, s->stats_vq_elem, 0);
-- 
2.21.0