Re: [PATCH v2 6/9] virtio_net: transmit the multi-buffer xdp

Jason Wang
2022-12-27T07:13:08Z

在 2022/12/20 22:14, Heng Qi 写道:
> This serves as the basis for XDP_TX and XDP_REDIRECT
> to send a multi-buffer xdp_frame.
>
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> drivers/net/virtio_net.c | 27 ++++++++++++++++++++++-----
> 1 file changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 40bc58fa57f5..9f31bfa7f9a6 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -563,22 +563,39 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
> struct xdp_frame *xdpf)
> {
> struct virtio_net_hdr_mrg_rxbuf *hdr;
> - int err;
> + struct skb_shared_info *shinfo;
> + u8 nr_frags = 0;
> + int err, i;
>
> if (unlikely(xdpf->headroom < vi->hdr_len))
> return -EOVERFLOW;
>
> - /* Make room for virtqueue hdr (also change xdpf->headroom?) */
> + if (unlikely(xdp_frame_has_frags(xdpf))) {
> + shinfo = xdp_get_shared_info_from_frame(xdpf);
> + nr_frags = shinfo->nr_frags;
> + }
> +
> + /* Need to adjust this to calculate the correct postion
> + * for shinfo of the xdpf.
> + */
> + xdpf->headroom -= vi->hdr_len;

Any reason we need to do this here? (Or if it is, is it only needed for
multibuffer XDP?)

Other looks good.

Thanks

> xdpf->data -= vi->hdr_len;
> /* Zero header and leave csum up to XDP layers */
> hdr = xdpf->data;
> memset(hdr, 0, vi->hdr_len);
> xdpf->len += vi->hdr_len;
>
> - sg_init_one(sq->sg, xdpf->data, xdpf->len);
> + sg_init_table(sq->sg, nr_frags + 1);
> + sg_set_buf(sq->sg, xdpf->data, xdpf->len);
> + for (i = 0; i < nr_frags; i++) {
> + skb_frag_t *frag = &shinfo->frags[i];
> +
> + sg_set_page(&sq->sg[i + 1], skb_frag_page(frag),
> + skb_frag_size(frag), skb_frag_off(frag));
> + }
>
> - err = virtqueue_add_outbuf(sq->vq, sq->sg, 1, xdp_to_ptr(xdpf),
> - GFP_ATOMIC);
> + err = virtqueue_add_outbuf(sq->vq, sq->sg, nr_frags + 1,
> + xdp_to_ptr(xdpf), GFP_ATOMIC);
> if (unlikely(err))
> return -ENOSPC; /* Caller handle free/refcnt */
>