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virtio-net: build xdp_buff with multi buffers

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Support xdp for multi buffer packets in mergeable mode.

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.

Let 'truesize' return to its literal meaning, that is, when
xdp is set, it includes the length of headroom and tailroom.

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Heng Qi 2023-01-14 16:22:24 +08:00 committed by David S. Miller
parent 50bd14bc98
commit ef75cb51f1
1 changed files with 100 additions and 8 deletions
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108
drivers/net/virtio_net.c
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@ -938,6 +938,91 @@ err:
return NULL;
}
/* TODO: build xdp in big mode */
static int virtnet_build_xdp_buff_mrg(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)
{
struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
unsigned int headroom, tailroom, room;
unsigned int truesize, cur_frag_size;
struct skb_shared_info *shinfo;
unsigned int xdp_frags_truesz = 0;
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);
if (*num_buf > 1) {
/* If we want to build multi-buffer xdp, we need
* to specify that the flags of xdp_buff have the
* XDP_FLAGS_HAS_FRAG bit.
*/
if (!xdp_buff_has_frags(xdp))
xdp_buff_set_frags_flag(xdp);
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);
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;
}
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);
tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
room = SKB_DATA_ALIGN(headroom + tailroom);
cur_frag_size = truesize;
xdp_frags_truesz += cur_frag_size;
if (unlikely(len > truesize - room || cur_frag_size > PAGE_SIZE)) {
put_page(page);
pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
dev->name, len, (unsigned long)(truesize - room));
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,
@ -956,15 +1041,17 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
unsigned int truesize = mergeable_ctx_to_truesize(ctx);
unsigned int headroom = mergeable_ctx_to_headroom(ctx);
unsigned int metasize = 0;
unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
unsigned int frame_sz;
int err;
head_skb = NULL;
stats->bytes += len - vi->hdr_len;
if (unlikely(len > truesize)) {
if (unlikely(len > truesize - room)) {
pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
dev->name, len, (unsigned long)ctx);
dev->name, len, (unsigned long)(truesize - room));
dev->stats.rx_length_errors++;
goto err_skb;
}
@ -990,10 +1077,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
if (unlikely(hdr->hdr.gso_type))
goto err_xdp;
/* Buffers with headroom use PAGE_SIZE as alloc size,
* see add_recvbuf_mergeable() + get_mergeable_buf_len()
/* Now XDP core assumes frag size is PAGE_SIZE, but buffers
* with headroom may add hole in truesize, which
* make their length exceed PAGE_SIZE. So we disabled the
* hole mechanism for xdp. See add_recvbuf_mergeable().
*/
frame_sz = headroom ? PAGE_SIZE : truesize;
frame_sz = truesize;
/* This happens when rx buffer size is underestimated
* or headroom is not enough because of the buffer
@ -1146,9 +1235,12 @@ skip_xdp:
page = virt_to_head_page(buf);
truesize = mergeable_ctx_to_truesize(ctx);
if (unlikely(len > truesize)) {
headroom = mergeable_ctx_to_headroom(ctx);
tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
room = SKB_DATA_ALIGN(headroom + tailroom);
if (unlikely(len > truesize - room)) {
pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
dev->name, len, (unsigned long)ctx);
dev->name, len, (unsigned long)(truesize - room));
dev->stats.rx_length_errors++;
goto err_skb;
}
@ -1435,7 +1527,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
}
sg_init_one(rq->sg, buf, len);
ctx = mergeable_len_to_ctx(len, headroom);
ctx = mergeable_len_to_ctx(len + room, headroom);
err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
if (err < 0)
put_page(virt_to_head_page(buf));