From 6d5c0e0e98907244d72e7828337d7ff6160b6b80 Mon Sep 17 00:00:00 2001 From: Ladi Prosek Date: Thu, 10 Nov 2016 23:00:51 +0100 Subject: [PATCH 8/8] virtio-balloon: fix stats vq migration RH-Author: Ladi Prosek Message-id: <1478797251-10302-2-git-send-email-lprosek@redhat.com> Patchwork-id: 72819 O-Subject: [PATCH v2 8/6] virtio-balloon: fix stats vq migration Bugzilla: 1393484 RH-Acked-by: Paolo Bonzini RH-Acked-by: Michael S. Tsirkin RH-Acked-by: Miroslav Rezanina The statistics virtqueue is not migrated properly because virtio-balloon does not include s->stats_vq_elem in the migration stream. After migration the statistics virtqueue hangs because the host never completes the last element (s->stats_vq_elem is NULL on the destination QEMU). Therefore the guest never submits new elements and the virtqueue is hung. Instead of changing the migration stream format in an incompatible way, detect the migration case and rewind the virtqueue so the last element can be completed. Cc: Michael S. Tsirkin Cc: Roman Kagan Cc: Stefan Hajnoczi Suggested-by: Roman Kagan Signed-off-by: Ladi Prosek Reviewed-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit 4a1e48becab81020adfb74b22c76a595f2d02a01) Signed-off-by: Ladi Prosek Signed-off-by: Miroslav Rezanina --- hw/virtio/virtio-balloon.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index faf93f7..1a60d3c 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -403,6 +403,18 @@ static void virtio_balloon_device_reset(VirtIODevice *vdev) } } +static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status) +{ + VirtIOBalloon *s = VIRTIO_BALLOON(vdev); + + if (!s->stats_vq_elem_pending && vdev->vm_running && + (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1)) { + /* poll stats queue for the element we have discarded when the VM + * was stopped */ + virtio_balloon_receive_stats(vdev, s->svq); + } +} + static Property virtio_balloon_properties[] = { DEFINE_PROP_END_OF_LIST(), }; @@ -419,6 +431,7 @@ static void virtio_balloon_class_init(ObjectClass *klass, void *data) vdc->get_config = virtio_balloon_get_config; vdc->set_config = virtio_balloon_set_config; vdc->get_features = virtio_balloon_get_features; + vdc->set_status = virtio_balloon_set_status; } static const TypeInfo virtio_balloon_info = { -- 1.8.3.1