[dpdk-stable] [PATCH] vhost: fix interrupt suppression for the split ring
Jiayu Hu
jiayu.hu at intel.com
Fri Feb 22 09:13:50 CET 2019
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: stable at dpdk.org
Signed-off-by: Jiayu Hu <jiayu.hu at 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
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