Re: [dpdk-dev] [PATCH] vhost: fix zmbuf buffer id invalid

[Maxime Coquelin <maxime.coquelin@redhat.com>]

I would make the title a bit more generic, e.g.:

vhost: fix packed ring zero-copy

On 2/24/20 3:50 PM, Marvin Liu wrote:
> zc mbufs should record available buffer id when doing dequeue zcopy.

Available buffer ID should be stored in the mbuf in the packed-ring
dequeue path.

> There's no guarantee that local queue avail index equal to buffer index.
> 
> Fixes: d1eafb532268 ("vhost: add packed ring zcopy batch and single dequeue")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Marvin Liu <yong.liu@intel.com>
> Reported-by: Yinan Wang <yinan.wang@intel.com>
> 
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 37c47c7dc..210415904 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -2004,7 +2004,7 @@ virtio_dev_tx_batch_packed_zmbuf(struct virtio_net *dev,
>  
>  	vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
>  		zmbufs[i]->mbuf = pkts[i];
> -		zmbufs[i]->desc_idx = avail_idx + i;
> +		zmbufs[i]->desc_idx = ids[i];
>  		zmbufs[i]->desc_count = 1;
>  	}
>  
> @@ -2045,7 +2045,7 @@ virtio_dev_tx_single_packed_zmbuf(struct virtio_net *dev,
>  		return -1;
>  	}
>  	zmbuf->mbuf = *pkts;
> -	zmbuf->desc_idx = vq->last_avail_idx;
> +	zmbuf->desc_idx = buf_id;
>  	zmbuf->desc_count = desc_count;
>  
>  	rte_mbuf_refcnt_update(*pkts, 1);
> 

With the commit message fixed:
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime