Re: [dpdk-dev] [PATCH v1 3/4] vhost: fix async vec buf overrun

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

s/buf/buffer/

On 9/11/20 3:53 AM, Patrick Fu wrote:
> Add check on the async vec buffer usage to prevent the buf overrun.

s/vec/vector/

s/buf/buffer/


> If vec buf is not sufficient to prepare for next packet's iov

same here

> creation, an async transfer will be triggered immediately to free
> the vec buf.
> 
> Fixes: 78639d54563a ("vhost: introduce async enqueue registration API")
> 
> Signed-off-by: Patrick Fu <patrick.fu@intel.com>
> ---
>  lib/librte_vhost/vhost.h      | 2 +-
>  lib/librte_vhost/virtio_net.c | 7 ++++++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 0af0ac23d..5e669e28f 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -47,7 +47,7 @@
>  #define MAX_PKT_BURST 32
>  
>  #define VHOST_MAX_ASYNC_IT (MAX_PKT_BURST * 2)
> -#define VHOST_MAX_ASYNC_VEC (BUF_VECTOR_MAX * 2)
> +#define VHOST_MAX_ASYNC_VEC (BUF_VECTOR_MAX * 4)
>  
>  #define PACKED_DESC_ENQUEUE_USED_FLAG(w)	\
>  	((w) ? (VRING_DESC_F_AVAIL | VRING_DESC_F_USED | VRING_DESC_F_WRITE) : \
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 70c3377fb..18b91836a 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -1492,6 +1492,7 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
>  	struct rte_vhost_iov_iter *dst_it = it_pool + 1;
>  	uint16_t n_free_slot, slot_idx;
>  	uint16_t pkt_err = 0;
> +	uint16_t segs_await = 0;
>  	struct async_inflight_info *pkts_info = vq->async_pkts_info;
>  	int n_pkts = 0;
>  
> @@ -1540,6 +1541,7 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
>  			dst_iovec += dst_it->nr_segs;
>  			src_it += 2;
>  			dst_it += 2;
> +			segs_await += src_it->nr_segs;
>  		} else {
>  			pkts_info[slot_idx].info = num_buffers;
>  			vq->async_pkts_inflight_n++;
> @@ -1548,13 +1550,16 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
>  		vq->last_avail_idx += num_buffers;
>  
>  		if (pkt_burst_idx >= VHOST_ASYNC_BATCH_THRESHOLD ||
> -				(pkt_idx == count - 1 && pkt_burst_idx)) {
> +				(pkt_idx == count - 1 && pkt_burst_idx) ||
> +				VHOST_MAX_ASYNC_VEC / 2 - segs_await <
> +				BUF_VECTOR_MAX) {

Parenthesis may help.

Or better to refactor the code for better readability.

>  			n_pkts = vq->async_ops.transfer_data(dev->vid,
>  					queue_id, tdes, 0, pkt_burst_idx);
>  			src_iovec = vec_pool;
>  			dst_iovec = vec_pool + (VHOST_MAX_ASYNC_VEC >> 1);
>  			src_it = it_pool;
>  			dst_it = it_pool + 1;
> +			segs_await = 0;
>  			vq->async_pkts_inflight_n += n_pkts;
>  
>  			if (unlikely(n_pkts < (int)pkt_burst_idx)) {
>