Re: [PATCH v5 00/13] virtio: introduce support for GSO over UDP tunnel

[Paolo Abeni <pabeni@redhat.com>]

On 9/1/25 4:47 AM, Jason Wang wrote:
> On Thu, Aug 28, 2025 at 9:47 AM Akihiko Odaki
> <odaki@rsg.ci.i.u-tokyo.ac.jp> wrote:
>>
>> On 2025/08/13 19:28, Paolo Abeni wrote:
>>> Some virtualized deployments use UDP tunnel pervasively and are impacted
>>> negatively by the lack of GSO support for such kind of traffic in the
>>> virtual NIC driver.
>>>
>>> The virtio_net specification recently introduced support for GSO over
>>> UDP tunnel, and the kernel side of the implementation has been merged
>>> into the net-next tree; this series updates the virtio implementation to
>>> support such a feature.
>>>
>>> Currently the qemu virtio support limits the feature space to 64 bits,
>>> while the virtio specification allows for a larger number of features.
>>> Specifically the GSO-over-UDP-tunnel-related virtio features use bits
>>> 65-69; the larger part of this series (patches 4-12) actually deals with
>>> extending the features space.
>>>
>>> The extended features are carried by fixed size uint64_t arrays,
>>> bringing the current maximum features number to 128.
>>>
>>> The patches use some syntactic sugar to try to minimize the otherwise
>>> very large code churn. Specifically the extended features are boundled
>>> in an union with 'legacy' features definition, allowing no changes in
>>> the virtio devices not needing the extended features set.
>>>
>>> The actual offload implementation is in patches 13 and 14 and boils down
>>> to propagating the new offload to the tun devices and the vhost backend.
>>>
>>> Patch 1 is a small pre-req refactor that ideally could enter the
>>> tree separately; it's presented here in the same series to help
>>> reviewers more easily getting the full picture, patch 2 updates to
>>> linux headers update script to deal with annotations recently introduce
>>> in the kernel and patch 3 is a needed linux headers update.
>>>
>>> Tested with basic stream transfer with all the possible permutations of
>>> host kernel/qemu/guest kernel with/without GSO over UDP tunnel support,
>>> vs snapshots creation and restore and vs migration.
>>>
>>> The new features are disabled by default to avoid compatibilty issues.
>>> They could be enabled after that hw_compat_10_1 will be added, together
>>> with the related compatiblity entries.
>>>
>>> Based-on: 9d71108d7de139dd4f4e6efe6837cabb32bf5616.1755078918.git.pabeni@redhat.com
>>
>> Now everything looks good to me. For the whole series:
>>
>> Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
>>
>> Regards,
>> Akihiko Odaki
>>
> 
> Acked-by: Jason Wang <jasowang@redhat.com>

Thank you for the feedback. I guess this series will go through
Micheal's tree, am I correct?

Also I suspect/fear it could need rebasing due to some other patches
being applied meanwhile, please LMK if a repost is needed, thanks!

Paolo