Re: [RFC] virtio-net: AF_XDP zero-copy TX checksum offload

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Mon, 5 Oct 2026 17:28:35 -0500, Azadeh Aftahi <aftahi334@gmail.com> wrote:
> Hi all,
>
> I'm planning to work on single-buffer AF_XDP zero-copy TX checksum offload for virtio-net.
>
> Current net-next's virtnet_xsk_xmit_one() does not consume XSK TX checksum metadata and uses the shared zeroed virtio header.
>
> I found Xuan's 2021 proposal anticipating separate headers for checksum support, and the merged 2024 zero-copy TX series, but I couldn't find a checksum-specific follow-up implementation.
>
> The proposed scope is to map the existing XSK checksum metadata API to VIRTIO_NET_F_CSUM, using a DMA-safe per-packet virtio header whose lifetime extends until TX completion, with corresponding completion, reset, and unbind cleanup.
>
> I would keep the initial scope limited to single-buffer TX: no multi-buffer RX, timestamps, launch time, or GSO.
>
> I'd also add checksum and header-lifetime coverage using the existing XSK selftest framework with QEMU/TAP.
>
> Is anyone already working on this? If not, does this scope and per-packet-header approach sound reasonable for a follow-up patch?

It seems no one has taken this work forward yet; I would welcome it if you were
to do so.

Thanks.


>
> Thanks,
> Azadeh