netdev - Re: [RFC PATCH 0/5] TUN/VirtioNet USO features support.

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Date:   Wed, 26 Jan 2022 15:52:17 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     Andrew Melnychenko <andrew@...nix.com>
Cc:     yan@...nix.com, yuri.benditovich@...nix.com, davem@...emloft.net,
        kuba@...nel.org, mst@...hat.com, jasowang@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [RFC PATCH 0/5] TUN/VirtioNet USO features support.

On Tue, 25 Jan 2022 10:46:57 +0200, Andrew Melnychenko <andrew@...nix.com> wrote:
> Added new offloads for TUN devices TUN_F_USO4 and TUN_F_USO6.
> Technically they enable NETIF_F_GSO_UDP_L4
> (and only if USO4 & USO6 are set simultaneously).
> It allows to transmission of large UDP packets.
>
> Different features USO4 and USO6 are required for qemu where Windows guests can
> enable disable USO receives for IPv4 and IPv6 separately.
> On the other side, Linux can't really differentiate USO4 and USO6, for now.
> For now, to enable USO for TUN it requires enabling USO4 and USO6 together.
> In the future, there would be a mechanism to control UDP_L4 GSO separately.
>
> Test it WIP Qemu https://github.com/daynix/qemu/tree/Dev_USOv2
>
> New types for VirtioNet already on mailing:
> https://lists.oasis-open.org/archives/virtio-comment/202110/msg00010.html

Seems like this hasn't been upvoted yet.

	https://github.com/oasis-tcs/virtio-spec#use-of-github-issues

Thanks.

>
> Also, there is a known issue with transmitting packages between two guests.
> Without hacks with skb's GSO - packages are still segmented on the host's postrouting.
>
> Andrew Melnychenko (5):
>   uapi/linux/if_tun.h: Added new ioctl for tun/tap.
>   driver/net/tun: Added features for USO.
>   uapi/linux/virtio_net.h: Added USO types.
>   linux/virtio_net.h: Added Support for GSO_UDP_L4 offload.
>   drivers/net/virtio_net.c: Added USO support.
>
>  drivers/net/tap.c               | 18 ++++++++++++++++--
>  drivers/net/tun.c               | 15 ++++++++++++++-
>  drivers/net/virtio_net.c        | 22 ++++++++++++++++++----
>  include/linux/virtio_net.h      | 11 +++++++++++
>  include/uapi/linux/if_tun.h     |  3 +++
>  include/uapi/linux/virtio_net.h |  4 ++++
>  6 files changed, 66 insertions(+), 7 deletions(-)
>
> --
> 2.34.1
>
> _______________________________________________
> Virtualization mailing list
> Virtualization@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

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