On 30/06/2016 09:31, Liang Li wrote:
> After live migration, 'guest-stats' can't get the expected memory
> status in the guest. This issue is caused by commit 4eae2a657d.
> The value of 's->stats_vq_elem' will be NULL after live migration,
> and the check in the function 'balloon_stats_poll_cb()' will
> prevent the 'virtio_notify()' from executing. So guest will not
> update the memory status.
>
> Signed-off-by: Liang Li <liang.z...@intel.com>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Cc: Ladi Prosek <lpro...@redhat.com>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> ---
> hw/virtio/virtio-balloon.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 557d3f9..cc6947f 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -98,13 +98,19 @@ static void balloon_stats_poll_cb(void *opaque)
> {
> VirtIOBalloon *s = opaque;
> VirtIODevice *vdev = VIRTIO_DEVICE(s);
> + VirtQueueElement elem = {0};
>
> - if (s->stats_vq_elem == NULL || !balloon_stats_supported(s)) {
> + if (!balloon_stats_supported(s)) {
> /* re-schedule */
> balloon_stats_change_timer(s, s->stats_poll_interval);
> return;
> }
>
> + if (s->stats_vq_elem == NULL) {
> + virtqueue_push(s->svq, &elem, 0);
> + virtio_notify(vdev, s->svq);
> + return;
> + }
> virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
> virtio_notify(vdev, s->svq);
> g_free(s->stats_vq_elem);
>
Hi, the right fix is to migrate s->stats_vq_elem if it is not NULL. See
how it's done in hw/char/virtio-serial.c's virtio_serial_save_device
(save) and fetch_active_ports_list (load).
Paolo
