Re: [PATCH 2/4] virtio-net: add support of UDP segmentation (USO) on the host

[Willem de Bruijn]

On Tue, May 11, 2021 at 12:43 AM Yuri Benditovich
<yuri.benditovich@xxxxxxxxxx> wrote:
>
> Large UDP packet provided by the guest with GSO type set to
> VIRTIO_NET_HDR_GSO_UDP_L4 will be divided to several UDP
> packets according to the gso_size field.
>
> Signed-off-by: Yuri Benditovich <yuri.benditovich@xxxxxxxxxx>
> ---
>  include/linux/virtio_net.h | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index b465f8f3e554..4ecf9a1ca912 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -51,6 +51,11 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
>                         ip_proto = IPPROTO_UDP;
>                         thlen = sizeof(struct udphdr);
>                         break;
> +               case VIRTIO_NET_HDR_GSO_UDP_L4:
> +                       gso_type = SKB_GSO_UDP_L4;
> +                       ip_proto = IPPROTO_UDP;
> +                       thlen = sizeof(struct udphdr);
> +                       break;

If adding a new VIRTIO_NET_HDR type I suggest adding separate IPv4 and
IPv6 variants, analogous to VIRTIO_NET_HDR_GSO_TCPV[46]. To avoid
having to infer protocol again, as for UDP fragmentation offload (the
retry case below this code).