> 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?
