Re: [PATCH net-next v2 16/21] virtio_net: xsk: rx: introduce add_recvbuf_xsk()

Michael S. Tsirkin
2023-11-09T08:12:41Z

On Tue, Nov 07, 2023 at 11:12:22AM +0800, Xuan Zhuo wrote:
> Implement the logic of filling rq with XSK buffers.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> drivers/net/virtio/main.c | 4 ++-
> drivers/net/virtio/virtio_net.h | 5 ++++
> drivers/net/virtio/xsk.c | 49 ++++++++++++++++++++++++++++++++-
> drivers/net/virtio/xsk.h | 2 ++
> 4 files changed, 58 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> index 6210a6e37396..15943a22e17d 100644
> --- a/drivers/net/virtio/main.c
> +++ b/drivers/net/virtio/main.c
> @@ -1798,7 +1798,9 @@ static bool try_fill_recv(struct virtnet_info *vi, struct virtnet_rq *rq,
> bool oom;
>
> do {
> - if (vi->mergeable_rx_bufs)
> + if (rq->xsk.pool)
> + err = virtnet_add_recvbuf_xsk(vi, rq, rq->xsk.pool, gfp);
> + else if (vi->mergeable_rx_bufs)
> err = add_recvbuf_mergeable(vi, rq, gfp);
> else if (vi->big_packets)
> err = add_recvbuf_big(vi, rq, gfp);

I'm not sure I understand. How does this handle mergeable flag still being set?

> diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
> index a13d6d301fdb..1242785e311e 100644
> --- a/drivers/net/virtio/virtio_net.h
> +++ b/drivers/net/virtio/virtio_net.h
> @@ -140,6 +140,11 @@ struct virtnet_rq {
>
> /* xdp rxq used by xsk */
> struct xdp_rxq_info xdp_rxq;
> +
> + struct xdp_buff **xsk_buffs;
> + u32 nxt_idx;
> + u32 num;
> + u32 size;
> } xsk;
> };
>
> diff --git a/drivers/net/virtio/xsk.c b/drivers/net/virtio/xsk.c
> index ea5804ddd44e..e737c3353212 100644
> --- a/drivers/net/virtio/xsk.c
> +++ b/drivers/net/virtio/xsk.c
> @@ -38,6 +38,41 @@ static void virtnet_xsk_check_queue(struct virtnet_sq *sq)
> netif_stop_subqueue(dev, qnum);
> }
>
> +int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct virtnet_rq *rq,
> + struct xsk_buff_pool *pool, gfp_t gfp)
> +{
> + struct xdp_buff **xsk_buffs;
> + dma_addr_t addr;
> + u32 len, i;
> + int err = 0;
> +
> + xsk_buffs = rq->xsk.xsk_buffs;
> +
> + if (rq->xsk.nxt_idx >= rq->xsk.num) {
> + rq->xsk.num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->xsk.size);
> + if (!rq->xsk.num)
> + return -ENOMEM;
> + rq->xsk.nxt_idx = 0;
> + }

Another manually rolled linked list implementation.
Please, don't.

> +
> + i = rq->xsk.nxt_idx;
> +
> + /* use the part of XDP_PACKET_HEADROOM as the virtnet hdr space */
> + addr = xsk_buff_xdp_get_dma(xsk_buffs[i]) - vi->hdr_len;
> + len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len;
> +
> + sg_init_table(rq->sg, 1);
> + sg_fill_dma(rq->sg, addr, len);
> +
> + err = virtqueue_add_inbuf(rq->vq, rq->sg, 1, xsk_buffs[i], gfp);
> + if (err)
> + return err;
> +
> + rq->xsk.nxt_idx++;
> +
> + return 0;
> +}
> +
> static int virtnet_xsk_xmit_one(struct virtnet_sq *sq,
> struct xsk_buff_pool *pool,
> struct xdp_desc *desc)
> @@ -213,7 +248,7 @@ static int virtnet_xsk_pool_enable(struct net_device *dev,
> struct virtnet_sq *sq;
> struct device *dma_dev;
> dma_addr_t hdr_dma;
> - int err;
> + int err, size;
>
> /* In big_packets mode, xdp cannot work, so there is no need to
> * initialize xsk of rq.
> @@ -249,6 +284,16 @@ static int virtnet_xsk_pool_enable(struct net_device *dev,
> if (!dma_dev)
> return -EPERM;
>
> + size = virtqueue_get_vring_size(rq->vq);
> +
> + rq->xsk.xsk_buffs = kcalloc(size, sizeof(*rq->xsk.xsk_buffs), GFP_KERNEL);
> + if (!rq->xsk.xsk_buffs)
> + return -ENOMEM;
> +
> + rq->xsk.size = size;
> + rq->xsk.nxt_idx = 0;
> + rq->xsk.num = 0;
> +
> hdr_dma = dma_map_single(dma_dev, &xsk_hdr, vi->hdr_len, DMA_TO_DEVICE);
> if (dma_mapping_error(dma_dev, hdr_dma))
> return -ENOMEM;
> @@ -307,6 +352,8 @@ static int virtnet_xsk_pool_disable(struct net_device *dev, u16 qid)
>
> dma_unmap_single(dma_dev, sq->xsk.hdr_dma_address, vi->hdr_len, DMA_TO_DEVICE);
>
> + kfree(rq->xsk.xsk_buffs);
> +
> return err1 | err2;
> }
>
> diff --git a/drivers/net/virtio/xsk.h b/drivers/net/virtio/xsk.h
> index 7ebc9bda7aee..bef41a3f954e 100644
> --- a/drivers/net/virtio/xsk.h
> +++ b/drivers/net/virtio/xsk.h
> @@ -23,4 +23,6 @@ int virtnet_xsk_pool_setup(struct net_device *dev, struct netdev_bpf *xdp);
> bool virtnet_xsk_xmit(struct virtnet_sq *sq, struct xsk_buff_pool *pool,
> int budget);
> int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag);
> +int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct virtnet_rq *rq,
> + struct xsk_buff_pool *pool, gfp_t gfp);
> #endif
> --
> 2.32.0.3.g01195cf9f