[PATCH v2 9/9] virtio_net: support multi-buffer xdp

Heng Qi
2022-12-20T14:15:17Z

Driver can pass the skb to stack by build_skb_from_xdp_buff().

Driver forwards multi-buffer packets using the send queue
when XDP_TX and XDP_REDIRECT, and clears the reference of multi
pages when XDP_DROP.

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
drivers/net/virtio_net.c | 65 ++++++----------------------------------
1 file changed, 9 insertions(+), 56 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 398ffe2a5084..daa380b9d1cc 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1074,7 +1074,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
struct bpf_prog *xdp_prog;
unsigned int truesize = mergeable_ctx_to_truesize(ctx);
unsigned int headroom = mergeable_ctx_to_headroom(ctx);
- unsigned int metasize = 0;
unsigned int frame_sz;
int err;

@@ -1165,63 +1164,22 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,

switch (act) {
case XDP_PASS:
- metasize = xdp.data - xdp.data_meta;
-
- /* recalculate offset to account for any header
- * adjustments and minus the metasize to copy the
- * metadata in page_to_skb(). Note other cases do not
- * build an skb and avoid using offset
- */
- offset = xdp.data - page_address(xdp_page) -
- vi->hdr_len - metasize;
-
- /* recalculate len if xdp.data, xdp.data_end or
- * xdp.data_meta were adjusted
- */
- len = xdp.data_end - xdp.data + vi->hdr_len + metasize;
-
- /* recalculate headroom if xdp.data or xdp_data_meta
- * were adjusted, note that offset should always point
- * to the start of the reserved bytes for virtio_net
- * header which are followed by xdp.data, that means
- * that offset is equal to the headroom (when buf is
- * starting at the beginning of the page, otherwise
- * there is a base offset inside the page) but it's used
- * with a different starting point (buf start) than
- * xdp.data (buf start + vnet hdr size). If xdp.data or
- * data_meta were adjusted by the xdp prog then the
- * headroom size has changed and so has the offset, we
- * can use data_hard_start, which points at buf start +
- * vnet hdr size, to calculate the new headroom and use
- * it later to compute buf start in page_to_skb()
- */
- headroom = xdp.data - xdp.data_hard_start - metasize;
-
- /* We can only create skb based on xdp_page. */
- if (unlikely(xdp_page != page)) {
- rcu_read_unlock();
- put_page(page);
- head_skb = page_to_skb(vi, rq, xdp_page, offset,
- len, PAGE_SIZE);
- return head_skb;
- }
- break;
+ head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
+ rcu_read_unlock();
+ return head_skb;
case XDP_TX:
stats->xdp_tx++;
xdpf = xdp_convert_buff_to_frame(&xdp);
if (unlikely(!xdpf)) {
- if (unlikely(xdp_page != page))
- put_page(xdp_page);
- goto err_xdp;
+ netdev_dbg(dev, "convert buff to frame failed for xdp\n");
+ goto err_xdp_frags;
}
err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
if (unlikely(!err)) {
xdp_return_frame_rx_napi(xdpf);
} else if (unlikely(err < 0)) {
trace_xdp_exception(vi->dev, xdp_prog, act);
- if (unlikely(xdp_page != page))
- put_page(xdp_page);
- goto err_xdp;
+ goto err_xdp_frags;
}
*xdp_xmit |= VIRTIO_XDP_TX;
if (unlikely(xdp_page != page))
@@ -1231,11 +1189,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
case XDP_REDIRECT:
stats->xdp_redirects++;
err = xdp_do_redirect(dev, &xdp, xdp_prog);
- if (err) {
- if (unlikely(xdp_page != page))
- put_page(xdp_page);
- goto err_xdp;
- }
+ if (err)
+ goto err_xdp_frags;
*xdp_xmit |= VIRTIO_XDP_REDIR;
if (unlikely(xdp_page != page))
put_page(page);
@@ -1248,9 +1203,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
trace_xdp_exception(vi->dev, xdp_prog, act);
fallthrough;
case XDP_DROP:
- if (unlikely(xdp_page != page))
- __free_pages(xdp_page, 0);
- goto err_xdp;
+ goto err_xdp_frags;
}
err_xdp_frags:
shinfo = xdp_get_shared_info_from_buff(&xdp);
--
2.19.1.6.gb485710b