Re: [PATCH net-next v5 11/15] virtio_net: xsk: tx: support xmit xsk buffer

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On Fri, Jun 14, 2024 at 2:40 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> The driver's tx napi is very important for XSK. It is responsible for
> obtaining data from the XSK queue and sending it out.
>
> At the beginning, we need to trigger tx napi.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
>  drivers/net/virtio_net.c | 121 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 119 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 2767338dc060..7e811f392768 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -535,10 +535,13 @@ enum virtnet_xmit_type {
>         VIRTNET_XMIT_TYPE_SKB,
>         VIRTNET_XMIT_TYPE_XDP,
>         VIRTNET_XMIT_TYPE_DMA,
> +       VIRTNET_XMIT_TYPE_XSK,
>  };
>
>  #define VIRTNET_XMIT_TYPE_MASK (VIRTNET_XMIT_TYPE_SKB | VIRTNET_XMIT_TYPE_XDP \
> -                               | VIRTNET_XMIT_TYPE_DMA)
> +                               | VIRTNET_XMIT_TYPE_DMA | VIRTNET_XMIT_TYPE_XSK)
> +
> +#define VIRTIO_XSK_FLAG_OFFSET 4
>
>  static enum virtnet_xmit_type virtnet_xmit_ptr_strip(void **ptr)
>  {
> @@ -768,6 +771,10 @@ static void __free_old_xmit(struct send_queue *sq, bool in_napi,
>                          * func again.
>                          */
>                         goto retry;
> +
> +               case VIRTNET_XMIT_TYPE_XSK:
> +                       /* Make gcc happy. DONE in subsequent commit */

This is probably a hint that the next patch should be squashed here.

> +                       break;
>                 }
>         }
>  }
> @@ -1265,6 +1272,102 @@ static void check_sq_full_and_disable(struct virtnet_info *vi,
>         }
>  }
>
> +static void *virtnet_xsk_to_ptr(u32 len)
> +{
> +       unsigned long p;
> +
> +       p = len << VIRTIO_XSK_FLAG_OFFSET;
> +
> +       return virtnet_xmit_ptr_mix((void *)p, VIRTNET_XMIT_TYPE_XSK);
> +}
> +
> +static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
> +{
> +       sg->dma_address = addr;
> +       sg->length = len;
> +}
> +
> +static int virtnet_xsk_xmit_one(struct send_queue *sq,
> +                               struct xsk_buff_pool *pool,
> +                               struct xdp_desc *desc)
> +{
> +       struct virtnet_info *vi;
> +       dma_addr_t addr;
> +
> +       vi = sq->vq->vdev->priv;
> +
> +       addr = xsk_buff_raw_get_dma(pool, desc->addr);
> +       xsk_buff_raw_dma_sync_for_device(pool, addr, desc->len);
> +
> +       sg_init_table(sq->sg, 2);
> +
> +       sg_fill_dma(sq->sg, sq->xsk.hdr_dma_address, vi->hdr_len);
> +       sg_fill_dma(sq->sg + 1, addr, desc->len);
> +
> +       return virtqueue_add_outbuf(sq->vq, sq->sg, 2,
> +                                   virtnet_xsk_to_ptr(desc->len), GFP_ATOMIC);
> +}
> +
> +static int virtnet_xsk_xmit_batch(struct send_queue *sq,
> +                                 struct xsk_buff_pool *pool,
> +                                 unsigned int budget,
> +                                 u64 *kicks)
> +{
> +       struct xdp_desc *descs = pool->tx_descs;
> +       bool kick = false;
> +       u32 nb_pkts, i;
> +       int err;
> +
> +       budget = min_t(u32, budget, sq->vq->num_free);
> +
> +       nb_pkts = xsk_tx_peek_release_desc_batch(pool, budget);
> +       if (!nb_pkts)
> +               return 0;
> +
> +       for (i = 0; i < nb_pkts; i++) {
> +               err = virtnet_xsk_xmit_one(sq, pool, &descs[i]);
> +               if (unlikely(err)) {
> +                       xsk_tx_completed(sq->xsk.pool, nb_pkts - i);
> +                       break;

Any reason we don't need a kick here?

> +               }
> +
> +               kick = true;
> +       }
> +
> +       if (kick && virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq))
> +               (*kicks)++;
> +
> +       return i;
> +}
> +
> +static bool virtnet_xsk_xmit(struct send_queue *sq, struct xsk_buff_pool *pool,
> +                            int budget)
> +{
> +       struct virtnet_info *vi = sq->vq->vdev->priv;
> +       struct virtnet_sq_free_stats stats = {};
> +       u64 kicks = 0;
> +       int sent;
> +
> +       __free_old_xmit(sq, true, &stats);
> +
> +       sent = virtnet_xsk_xmit_batch(sq, pool, budget, &kicks);
> +
> +       if (!is_xdp_raw_buffer_queue(vi, sq - vi->sq))
> +               check_sq_full_and_disable(vi, vi->dev, sq);
> +
> +       u64_stats_update_begin(&sq->stats.syncp);
> +       u64_stats_add(&sq->stats.packets, stats.packets);
> +       u64_stats_add(&sq->stats.bytes,   stats.bytes);
> +       u64_stats_add(&sq->stats.kicks,   kicks);
> +       u64_stats_add(&sq->stats.xdp_tx,  sent);
> +       u64_stats_update_end(&sq->stats.syncp);
> +
> +       if (xsk_uses_need_wakeup(pool))
> +               xsk_set_tx_need_wakeup(pool);
> +
> +       return sent == budget;
> +}
> +
>  static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
>                                    struct send_queue *sq,
>                                    struct xdp_frame *xdpf)
> @@ -2707,6 +2810,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
>         struct virtnet_info *vi = sq->vq->vdev->priv;
>         unsigned int index = vq2txq(sq->vq);
>         struct netdev_queue *txq;
> +       bool xsk_busy = false;
>         int opaque;
>         bool done;
>
> @@ -2719,7 +2823,11 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
>         txq = netdev_get_tx_queue(vi->dev, index);
>         __netif_tx_lock(txq, raw_smp_processor_id());
>         virtqueue_disable_cb(sq->vq);
> -       free_old_xmit(sq, true);
> +
> +       if (sq->xsk.pool)
> +               xsk_busy = virtnet_xsk_xmit(sq, sq->xsk.pool, budget);

How about rename this to "xsk_sent"?

> +       else
> +               free_old_xmit(sq, true);
>
>         if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) {
>                 if (netif_tx_queue_stopped(txq)) {
> @@ -2730,6 +2838,11 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
>                 netif_tx_wake_queue(txq);
>         }
>
> +       if (xsk_busy) {
> +               __netif_tx_unlock(txq);
> +               return budget;
> +       }
> +
>         opaque = virtqueue_enable_cb_prepare(sq->vq);
>
>         done = napi_complete_done(napi, 0);
> @@ -5715,6 +5828,10 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
>         case VIRTNET_XMIT_TYPE_DMA:
>                 virtnet_sq_unmap(sq, &buf);
>                 goto retry;
> +
> +       case VIRTNET_XMIT_TYPE_XSK:
> +               /* Make gcc happy. DONE in subsequent commit */
> +               break;
>         }
>  }
>
> --
> 2.32.0.3.g01195cf9f
>

Thanks






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