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

[Yuri Benditovich]

On Wed, Jan 26, 2022 at 9:54 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, 25 Jan 2022 10:46:57 +0200, Andrew Melnychenko <andrew@xxxxxxxxxx> 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

Yes, correct. This is a reason why this series of patches is RFC.

>
> 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
> >
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