On Thu, Nov 27, 2025 at 12:12 AM Jon Kohler <[email protected]> wrote: > > > > > On Nov 26, 2025, at 1:29 AM, Jason Wang <[email protected]> wrote: > > > > On Wed, Nov 26, 2025 at 5:46 AM Jon Kohler <[email protected]> wrote: > >> > >> Commit a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP > >> GSO tunneling.") inadvertently altered checksum offload behavior > >> for guests not using UDP GSO tunneling. > >> > >> Before, tun_put_user called tun_vnet_hdr_from_skb, which passed > >> has_data_valid = true to virtio_net_hdr_from_skb. > >> > >> After, tun_put_user began calling tun_vnet_hdr_tnl_from_skb instead, > >> which passes has_data_valid = false into both call sites. > >> > >> This caused virtio hdr flags to not include VIRTIO_NET_HDR_F_DATA_VALID > >> for SKBs where skb->ip_summed == CHECKSUM_UNNECESSARY. As a result, > >> guests are forced to recalculate checksums unnecessarily. > >> > >> Restore the previous behavior by ensuring has_data_valid = true is > >> passed in the !tnl_gso_type case, but only from tun side, as > >> virtio_net_hdr_tnl_from_skb() is used also by the virtio_net driver, > >> which in turn must not use VIRTIO_NET_HDR_F_DATA_VALID on tx. > >> > >> Cc: Paolo Abeni <[email protected]> > >> Fixes: a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP GSO > >> tunneling.") > >> Signed-off-by: Jon Kohler <[email protected]> > >> --- > > > > Acked-by: Jason Wang <[email protected]> > > > > (Should this go -stable?) > > > > Thanks > > It could, sure. This made it into 6.17 branch. > > Would you like me to send a separate patch with a Cc: stable > or could someone just edit the commit msg when they queue > this?
I think a new version might be better. Thanks
