Re: [PATCH 08/17] net/virtio: implement receive path for packed queues

[Tiwei Bie <tiwei.bie@intel.com>]

On Fri, Mar 16, 2018 at 04:21:11PM +0100, Jens Freimann wrote:
[...]
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 722a2cd..888cc49 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -1352,6 +1352,8 @@ static int virtio_dev_xstats_get_names(struct rte_eth_dev *dev,
>  		PMD_INIT_LOG(INFO, "virtio: using simple Rx path on port %u",
>  			eth_dev->data->port_id);
>  		eth_dev->rx_pkt_burst = virtio_recv_pkts_vec;
> +	} else if (vtpci_packed_queue(hw)) {
> +		eth_dev->rx_pkt_burst = &virtio_recv_pkts_packed;

If MRG_RXBUF isn't supported at this point, then we will
need to make sure that RING_PACKED and MRG_RXBUF won't be
negotiated at the same time. Otherwise this commit will
break the driver.

>  	} else if (vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF)) {
>  		PMD_INIT_LOG(INFO,
>  			"virtio: using mergeable buffer Rx path on port %u",
> @@ -1507,7 +1509,8 @@ static int virtio_dev_xstats_get_names(struct rte_eth_dev *dev,
>  
>  	/* Setting up rx_header size for the device */
>  	if (vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF) ||
> -	    vtpci_with_feature(hw, VIRTIO_F_VERSION_1))
> +	    vtpci_with_feature(hw, VIRTIO_F_VERSION_1) ||
> +	    vtpci_with_feature(hw, VIRTIO_F_RING_PACKED))
>  		hw->vtnet_hdr_size = sizeof(struct virtio_net_hdr_mrg_rxbuf);
>  	else
>  		hw->vtnet_hdr_size = sizeof(struct virtio_net_hdr);
[...]
>  #ifdef RTE_LIBRTE_VIRTIO_DEBUG_DUMP
>  #define VIRTIO_DUMP_PACKET(m, len) rte_pktmbuf_dump(stdout, m, len)
> @@ -428,6 +429,34 @@
>  
>  	PMD_INIT_FUNC_TRACE();
>  
> +	if (vtpci_packed_queue(hw)) {
> +		struct vring_desc_packed *desc;
> +		struct vq_desc_extra *dxp;
> +
> +		for (desc_idx = 0; desc_idx < vq->vq_nentries;
> +				desc_idx++) {
> +			m = rte_mbuf_raw_alloc(rxvq->mpool);
> +			if (unlikely(m == NULL))
> +				return -ENOMEM;
> +
> +			dxp = &vq->vq_descx[desc_idx];
> +			dxp->cookie = m;
> +			dxp->ndescs = 1;
> +
> +			desc = &vq->vq_ring.desc_packed[desc_idx];
> +			desc->addr = VIRTIO_MBUF_ADDR(m, vq) +
> +				RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
> +			desc->len = m->buf_len - RTE_PKTMBUF_HEADROOM +
> +				hw->vtnet_hdr_size;
> +			desc->flags |= VRING_DESC_F_WRITE;
> +			rte_smp_wmb();
> +			set_desc_avail(&vq->vq_ring, desc);
> +		}
> +		toggle_wrap_counter(&vq->vq_ring);
> +
> +		return 0;

Maybe it's better to give the debug code (which is at the
end of this function) a chance to run.

Thanks