在 2022/12/6 下午2:14, Jason Wang 写道:
On Tue, Nov 22, 2022 at 3:44 PM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote:Support xdp for multi buffer packets. Putting the first buffer as the linear part for xdp_buff, and the rest of the buffers as non-linear fragments to struct skb_shared_info in the tailroom belonging to xdp_buff. Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> Reviewed-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> --- drivers/net/virtio_net.c | 74 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index cd65f85d5075..20784b1d8236 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -911,6 +911,80 @@ static struct sk_buff *receive_big(struct net_device *dev, return NULL; } +static int virtnet_build_xdp_buff(struct net_device *dev, + struct virtnet_info *vi, + struct receive_queue *rq, + struct xdp_buff *xdp, + void *buf, + unsigned int len, + unsigned int frame_sz, + u16 *num_buf, + unsigned int *xdp_frags_truesize, + struct virtnet_rq_stats *stats) +{ + unsigned int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + struct virtio_net_hdr_mrg_rxbuf *hdr = buf; + unsigned int truesize, headroom; + struct skb_shared_info *shinfo; + unsigned int xdp_frags_truesz = 0; + unsigned int cur_frag_size; + struct page *page; + skb_frag_t *frag; + int offset; + void *ctx; + + xdp_init_buff(xdp, frame_sz, &rq->xdp_rxq); + xdp_prepare_buff(xdp, buf - VIRTIO_XDP_HEADROOM, + VIRTIO_XDP_HEADROOM + vi->hdr_len, len - vi->hdr_len, true); + shinfo = xdp_get_shared_info_from_buff(xdp); + shinfo->nr_frags = 0; + shinfo->xdp_frags_size = 0; + + if ((*num_buf - 1) > MAX_SKB_FRAGS) + return -EINVAL; + + while ((--*num_buf) >= 1) { + buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);So this works only for a mergeable buffer, I wonder if it's worth it to make it work for big mode as well. Or at least we can mention it as a TODO somewhere and rename this function (with mergeable suffix).
Yes, I'm leaning towards the latter, I'll rename it with a mergeable suffix in the next version.
Thanks.
Others look good. Thanks+ if (unlikely(!buf)) { + pr_debug("%s: rx error: %d buffers out of %d missing\n", + dev->name, *num_buf, + virtio16_to_cpu(vi->vdev, hdr->num_buffers)); + dev->stats.rx_length_errors++; + return -EINVAL; + } + + if (!xdp_buff_has_frags(xdp)) + xdp_buff_set_frags_flag(xdp); + + stats->bytes += len; + page = virt_to_head_page(buf); + offset = buf - page_address(page); + truesize = mergeable_ctx_to_truesize(ctx); + headroom = mergeable_ctx_to_headroom(ctx); + + cur_frag_size = truesize + (headroom ? (headroom + tailroom) : 0); + xdp_frags_truesz += cur_frag_size; + if (unlikely(len > truesize || cur_frag_size > PAGE_SIZE)) { + pr_debug("%s: rx error: len %u exceeds truesize %lu\n", + dev->name, len, (unsigned long)ctx); + dev->stats.rx_length_errors++; + return -EINVAL; + } + + frag = &shinfo->frags[shinfo->nr_frags++]; + __skb_frag_set_page(frag, page); + skb_frag_off_set(frag, offset); + skb_frag_size_set(frag, len); + if (page_is_pfmemalloc(page)) + xdp_buff_set_frag_pfmemalloc(xdp); + + shinfo->xdp_frags_size += len; + } + + *xdp_frags_truesize = xdp_frags_truesz; + return 0; +} + static struct sk_buff *receive_mergeable(struct net_device *dev, struct virtnet_info *vi, struct receive_queue *rq, -- 2.19.1.6.gb485710b
