[Qemu-devel] [PATCH 3/3] virtio-balloon: fix stats vq migration
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
---
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 ad4189a..49a2f4a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -469,6 +469,18 @@ 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 && 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 void virtio_balloon_instance_init(Object *obj)
{
VirtIOBalloon *s = VIRTIO_BALLOON(obj);
@@ -506,6 +518,7 @@ static void virtio_balloon_class_init(ObjectClass *klass,
void *data)
vdc->get_features = virtio_balloon_get_features;
vdc->save = virtio_balloon_save_device;
vdc->load = virtio_balloon_load_device;
+vdc->set_status = virtio_balloon_set_status;
}
static const TypeInfo virtio_balloon_info = {
--
2.5.5
Re: [Qemu-devel] [PATCH 3/3] virtio-balloon: fix stats vq migration
On Wed, Sep 07, 2016 at 05:20:49PM +0200, Ladi Prosek wrote: > 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 > --- > hw/virtio/virtio-balloon.c | 13 + > 1 file changed, 13 insertions(+) Reviewed-by: Stefan Hajnoczi signature.asc Description: PGP signature
Re: [Qemu-devel] [PATCH 3/3] virtio-balloon: fix stats vq migration
On Wed, Sep 07, 2016 at 05:20:49PM +0200, Ladi Prosek wrote: > 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 > --- > hw/virtio/virtio-balloon.c | 13 + > 1 file changed, 13 insertions(+) Reviewed-by: Roman Kagan
