Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

[Heng Qi]

在 2024/1/24 下午4:57, Liang Chen 写道:
For the XDP_PASS scenario of the XDP path, the skb constructed with
xdp_buff does not include the virtio header. Adding the virtio header
information back when creating the skb.

Signed-off-by: Liang Chen <liangchen.li...@gmail.com>
---
  drivers/net/virtio_net.c | 6 ++++++
  1 file changed, 6 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b56828804e5f..2de46eb4c661 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1270,6 +1270,9 @@ static struct sk_buff *receive_small_xdp(struct 
net_device *dev,
        if (unlikely(!skb))
                goto err;
  
+	/* Store the original virtio header for subsequent use by the driver. */
+       memcpy(skb_vnet_common_hdr(skb), &virtnet_xdp.hdr, vi->hdr_len);

If xdp push or xdp pull modifies xdp_buff, will the original header 
still apply to the modified data?

Thanks,
Heng

+
        if (metasize)
                skb_metadata_set(skb, metasize);
  
@@ -1635,6 +1638,9 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
                head_skb = build_skb_from_xdp_buff(dev, vi, xdp, 
xdp_frags_truesz);
                if (unlikely(!head_skb))
                        break;
+               /* Store the original virtio header for subsequent use by the 
driver. */
+               memcpy(skb_vnet_common_hdr(head_skb), &virtnet_xdp.hdr, 
vi->hdr_len);
+
                return head_skb;
  
  	case XDP_TX: