Re: [PATCH net v4 3/4] virtio-net: correct hdr_len handling for VIRTIO_NET_F_GUEST_HDRLEN

[Jason Wang]

On Mon, Nov 10, 2025 at 5:41 AM Michael S. Tsirkin <m...@redhat.com> wrote:
>
> On Thu, Oct 30, 2025 at 10:53:01AM +0800, Jason Wang wrote:
> > On Wed, Oct 29, 2025 at 11:09 AM Xuan Zhuo <xuanz...@linux.alibaba.com> 
> > wrote:
> > >
> > > The commit be50da3e9d4a ("net: virtio_net: implement exact header length
> > > guest feature") introduces support for the VIRTIO_NET_F_GUEST_HDRLEN
> > > feature in virtio-net.
> > >
> > > This feature requires virtio-net to set hdr_len to the actual header
> > > length of the packet when transmitting, the number of
> > > bytes from the start of the packet to the beginning of the
> > > transport-layer payload.
> > >
> > > However, in practice, hdr_len was being set using skb_headlen(skb),
> > > which is clearly incorrect. This commit fixes that issue.
> >
> > I still think it would be more safe to check the feature
>
> which feature VIRTIO_NET_F_GUEST_HDRLEN ?
>

Yes.

Thanks