On Tue, Jul 08, 2025 at 09:08:56AM +0200, 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, this series updates the virtio implementation to support > such a feature. > > Currently the kernel virtio support limits the feature space to 64, > 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 first four patches in this series rework the virtio and vhost > feature support to cope with up to 128 bits. The limit is set by > a define and could be easily raised in future, as needed. > > This implementation choice is aimed at keeping the code churn as > limited as possible. For the same reason, only the virtio_net driver is > reworked to leverage the extended feature space; all other > virtio/vhost drivers are unaffected, but could be upgraded to support > the extended features space in a later time. > > The last four patches bring in the actual GSO over UDP tunnel support. > As per specification, some additional fields are introduced into the > virtio net header to support the new offload. The presence of such > fields depends on the negotiated features. > > New helpers are introduced to convert the UDP-tunneled skb metadata to > an extended virtio net header and vice versa. Such helpers are used by > the tun and virtio_net driver to cope with the newly supported offloads. > > Tested with basic stream transfer with all the possible permutations of > host kernel/qemu/guest kernel with/without GSO over UDP tunnel support. > --- > WRT the merge plan, this is also are available in the Git repository at > [1]: > > git@xxxxxxxxxx:pabeni/linux-devel.git virtio_udp_tunnel_07_07_2025 > > The first 5 patches in this series, that is, the virtio features > extension bits are also available at [2]: > > git@xxxxxxxxxx:pabeni/linux-devel.git virtio_features_extension_07_07_2025 > > Ideally the virtio features extension bit should go via the virtio tree > and the virtio_net/tun patches via the net-next tree. The latter have > a dependency in the first and will cause conflicts if merged via the > virtio tree, both when applied and at merge window time - inside Linus > tree. > > To avoid such conflicts and duplicate commits I think the net-next > could pull from [1], while the virtio tree could pull from [2]. Or I could just merge all of this in my tree, if that's ok with others? Willem/Jason ok with you? > --- > v6 -> v7: > - avoid warning in csky build > - rebased > v6: https://lore.kernel.org/netdev/cover.1750753211.git.pabeni@xxxxxxxxxx/ > > v5 -> v6: > - fix integer overflow in patch 4/9 > v5: https://lore.kernel.org/netdev/cover.1750436464.git.pabeni@xxxxxxxxxx/ > > v4 -> v5: > - added new patch 1/9 to avoid kdoc issues > - encapsulate guest features guessing in new tap helper > - cleaned-up SET_FEATURES_ARRAY > - a few checkpatch fixes > v4: https://lore.kernel.org/netdev/cover.1750176076.git.pabeni@xxxxxxxxxx/ > > v3 -> v4: > - vnet sockopt cleanup > - fixed offset for UDP-tunnel related field > - use dev->features instead of flags > v3: https://lore.kernel.org/netdev/cover.1749210083.git.pabeni@xxxxxxxxxx/ > > v2 -> v3: > - uint128_t -> u64[2] > - dropped related ifdef > - define and use vnet_hdr with tunnel layouts > v2: https://lore.kernel.org/netdev/cover.1748614223.git.pabeni@xxxxxxxxxx/ > > v1 -> v2: > - fix build failures > - many comment clarification > - changed the vhost_net ioctl API > - fixed some hdr <> skb helper bugs > v1: https://lore.kernel.org/netdev/cover.1747822866.git.pabeni@xxxxxxxxxx/ > > Paolo Abeni (9): > scripts/kernel_doc.py: properly handle VIRTIO_DECLARE_FEATURES > virtio: introduce extended features > virtio_pci_modern: allow configuring extended features > vhost-net: allow configuring extended features > virtio_net: add supports for extended offloads > net: implement virtio helpers to handle UDP GSO tunneling. > virtio_net: enable gso over UDP tunnel support. > tun: enable gso over UDP tunnel support. > vhost/net: enable gso over UDP tunnel support. > > drivers/net/tun.c | 58 ++++++-- > drivers/net/tun_vnet.h | 101 +++++++++++-- > drivers/net/virtio_net.c | 110 +++++++++++--- > drivers/vhost/net.c | 95 +++++++++--- > drivers/vhost/vhost.c | 2 +- > drivers/vhost/vhost.h | 4 +- > drivers/virtio/virtio.c | 43 +++--- > drivers/virtio/virtio_debug.c | 27 ++-- > drivers/virtio/virtio_pci_modern.c | 10 +- > drivers/virtio/virtio_pci_modern_dev.c | 69 +++++---- > include/linux/virtio.h | 9 +- > include/linux/virtio_config.h | 43 +++--- > include/linux/virtio_features.h | 88 +++++++++++ > include/linux/virtio_net.h | 197 ++++++++++++++++++++++++- > include/linux/virtio_pci_modern.h | 43 +++++- > include/uapi/linux/if_tun.h | 9 ++ > include/uapi/linux/vhost.h | 7 + > include/uapi/linux/vhost_types.h | 5 + > include/uapi/linux/virtio_net.h | 33 +++++ > scripts/lib/kdoc/kdoc_parser.py | 1 + > 20 files changed, 790 insertions(+), 164 deletions(-) > create mode 100644 include/linux/virtio_features.h > > -- > 2.49.0
