[PATCH net] vhost: correctly check the iova range when waking virtqueue

[PATCH net] vhost: correctly check the iova range when waking virtqueue

[Jason Wang]

We don't wakeup the virtqueue if the first byte of pending iova range
is the last byte of the range we just got updated. This will lead a
virtqueue to wait for IOTLB updating forever. Fixing by correct the
check and wake up the virtqueue in this case.

Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
Reported-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
The patch is needed for -stable.
---
 drivers/vhost/vhost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 96c1d8400822..b13c6b4b2c66 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -952,7 +952,7 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
 	list_for_each_entry_safe(node, n, &d->pending_list, node) {
 		struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
 		if (msg->iova <= vq_msg->iova &&
-		    msg->iova + msg->size - 1 > vq_msg->iova &&
+		    msg->iova + msg->size - 1 >= vq_msg->iova &&
 		    vq_msg->type == VHOST_IOTLB_MISS) {
 			vhost_poll_queue(&node->vq->poll);
 			list_del(&node->node);
-- 
2.17.1

Re: [PATCH net] vhost: correctly check the iova range when waking virtqueue

[Peter Xu]

On Fri, Aug 24, 2018 at 04:53:13PM +0800, Jason Wang wrote:
> We don't wakeup the virtqueue if the first byte of pending iova range
> is the last byte of the range we just got updated. This will lead a
> virtqueue to wait for IOTLB updating forever. Fixing by correct the
> check and wake up the virtqueue in this case.
> 
> Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
> Reported-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Without this patch, this command will trigger the IO hang merely every
time from host to guest:

  netperf -H 1.2.3.4 -l 5 -t TCP_RR -- -b 100

After applying, I can run it 10 times continuously without a problem.

Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: Peter Xu <peterx@redhat.com>

Thanks,

-- 
Peter Xu

Re: [PATCH net] vhost: correctly check the iova range when waking virtqueue

[Michael S. Tsirkin]

On Fri, Aug 24, 2018 at 04:53:13PM +0800, Jason Wang wrote:
> We don't wakeup the virtqueue if the first byte of pending iova range
> is the last byte of the range we just got updated. This will lead a
> virtqueue to wait for IOTLB updating forever. Fixing by correct the
> check and wake up the virtqueue in this case.
> 
> Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
> Reported-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
> The patch is needed for -stable.
> ---
>  drivers/vhost/vhost.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 96c1d8400822..b13c6b4b2c66 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -952,7 +952,7 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
>  	list_for_each_entry_safe(node, n, &d->pending_list, node) {
>  		struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
>  		if (msg->iova <= vq_msg->iova &&
> -		    msg->iova + msg->size - 1 > vq_msg->iova &&
> +		    msg->iova + msg->size - 1 >= vq_msg->iova &&
>  		    vq_msg->type == VHOST_IOTLB_MISS) {
>  			vhost_poll_queue(&node->vq->poll);
>  			list_del(&node->node);
> -- 
> 2.17.1

Re: [PATCH net] vhost: correctly check the iova range when waking virtqueue

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Fri, 24 Aug 2018 16:53:13 +0800

> We don't wakeup the virtqueue if the first byte of pending iova range
> is the last byte of the range we just got updated. This will lead a
> virtqueue to wait for IOTLB updating forever. Fixing by correct the
> check and wake up the virtqueue in this case.
> 
> Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
> Reported-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> The patch is needed for -stable.

Applied and queued up for -stable, thanks Jason.