The VIRTIO_RING_F_EVENT_IDX feature of split ring might be broken, as the value of signalled_used is unpredictable after live migration or start up. This patch fixes it by using signalled_used_valid.
In addition, this patch makes the VIRTIO_RING_F_EVENT_IDX implementation of split ring match kernel backend to suppress more interrupts. Fixes: e37ff954405a ("vhost: support virtqueue interrupt/notification suppression") Cc: sta...@dpdk.org Signed-off-by: Jiayu Hu <jiayu...@intel.com> --- lib/librte_vhost/vhost.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index fc31796..c4e5e34 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -633,16 +633,20 @@ vhost_vring_call_split(struct virtio_net *dev, struct vhost_virtqueue *vq) if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) { uint16_t old = vq->signalled_used; uint16_t new = vq->last_used_idx; + bool signalled_used_valid = vq->signalled_used_valid; + + vq->signalled_used = new; + vq->signalled_used_valid = true; VHOST_LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n", __func__, vhost_used_event(vq), old, new); - if (vhost_need_event(vhost_used_event(vq), new, old) - && (vq->callfd >= 0)) { - vq->signalled_used = vq->last_used_idx; + + if ((vhost_need_event(vhost_used_event(vq), new, old) && + (vq->callfd >= 0)) || + unlikely(!signalled_used_valid)) eventfd_write(vq->callfd, (eventfd_t) 1); - } } else { /* Kick the guest if necessary. */ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT) -- 2.7.4