static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
VirtQueueElement *elem = &s->stats_vq_elem;
VirtIOBalloonStat stat;
size_t offset = 0;
if (!virtqueue_pop(vq, elem)) {
return;
}
/* Initialize the stats to get rid of any stale values. This is only
* needed to handle the case where a guest supports fewer stats than it
* used to (ie. it has booted into an old kernel).
*/
reset_stats(s);
while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))
== sizeof(stat)) {
uint16_t tag = tswap16(stat.tag);
uint64_t val = tswap64(stat.val);
offset += sizeof(stat);
if (tag < VIRTIO_BALLOON_S_NR)
s->stats[tag] = val;
}
s->stats_vq_offset = offset;
complete_stats_request(s);
}
static void virtio_balloon_stat(void *opaque, MonitorCompletion cb,
void *cb_data)
{
VirtIOBalloon *dev = opaque;
/* For now, only allow one request at a time. This restriction can be
* removed later by queueing callback and data pairs.
*/
if (dev->stats_callback != NULL) {
return;
}
dev->stats_callback = cb;
dev->stats_opaque_callback_data = cb_data;
if (ENABLE_GUEST_STATS
&& (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ))) {
virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
virtio_notify(&dev->vdev, dev->svq);
return;
}
/* Stats are not supported. Clear out any stale values that might
* have been set by a more featureful guest kernel.
*/
reset_stats(dev);
complete_stats_request(dev);
}
