vhost: fix packed ring zero-copy

  Available buffer ID should be stored in the zmbuf in the packed-ring
dequeue path. There's no guarantee that local queue avail index is
equal to buffer ID.

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>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
  

Tested-by: Xiao, QimaiX <qimaix.xiao@intel.com>

Regards,
Xiao Qimai

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Marvin Liu
> Sent: Monday, March 16, 2020 11:38 PM
> To: maxime.coquelin@redhat.com; Wang, Zhihong
> <zhihong.wang@intel.com>; Ye, Xiaolong <xiaolong.ye@intel.com>
> Cc: dev@dpdk.org; stable@dpdk.org; Liu, Yong <yong.liu@intel.com>
> Subject: [dpdk-dev] [PATCH] vhost: fix packed ring zero-copy
> 
> Available buffer ID should be stored in the zmbuf in the packed-ring
> dequeue path. There's no guarantee that local queue avail index is equal to
> buffer ID.
> 
> 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>
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.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);
> --
> 2.17.1
  

On 3/16/20 4:38 PM, Marvin Liu wrote:
> Available buffer ID should be stored in the zmbuf in the packed-ring
> dequeue path. There's no guarantee that local queue avail index is
> equal to buffer ID.
> 
> 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>
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Applied to dpdk-next-virtio/master.

Thanks,
Maxime