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]. --- 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
