linux-kernel - Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP

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Message-ID: <1706087654.2583706-2-xuanzhuo@linux.alibaba.com>
Date: Wed, 24 Jan 2024 17:14:14 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: Liang Chen <liangchen.linux@...il.com>
Cc: virtualization@...ts.linux-foundation.org,
 linux-kernel@...r.kernel.org,
 liangchen.linux@...il.com,
 mst@...hat.com,
 jasowang@...hat.com,
 hengqi@...ux.alibaba.com
Subject: Re: [PATCH v2 2/3] virtio_net: Add missing virtio header in skb for XDP_PASS

On Wed, 24 Jan 2024 16:57:20 +0800, Liang Chen <liangchen.linux@...il.com> wrote:
> 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.linux@...il.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);

About this, a spec is waiting for voting.

This may change the logic of the csum offset and so on.

Please not do this.

Thanks.


> +
>  	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:
> --
> 2.40.1
>