On Tue, May 24, 2022 at 7:07 PM Andrew Melnichenko <and...@daynix.com> wrote: > > Hi all, > > The issue is that host segments packets between guests on the same host. > Tests show that it happens because SKB_GSO_DODGY skb offload in > virtio_net_hdr_from_skb(). > To do segmentation you need to remove SKB_GSO_DODGY or add SKB_GSO_PARTIAL > The solution with DODGY/PARTIAL offload looks like a dirty hack, so > for now, I've lived it as it is for further investigation.
Ok, I managed to find the previous discussion. It looks to me the reason is that __udp_gso_segment will segment dodgy packets unconditionally. I wonder if the attached patch works? (compile test only). Thanks > > > On Tue, May 17, 2022 at 9:32 AM Jason Wang <jasow...@redhat.com> wrote: > > > > On Thu, May 12, 2022 at 7:33 PM Andrew Melnychenko <and...@daynix.com> > > wrote: > > > > > > Added new offloads for TUN devices TUN_F_USO4 and TUN_F_USO6. > > > Technically they enable NETIF_F_GSO_UDP_L4 > > > (and only if USO4 & USO6 are set simultaneously). > > > It allows to transmission of large UDP packets. > > > > > > Different features USO4 and USO6 are required for qemu where Windows > > > guests can > > > enable disable USO receives for IPv4 and IPv6 separately. > > > On the other side, Linux can't really differentiate USO4 and USO6, for > > > now. > > > For now, to enable USO for TUN it requires enabling USO4 and USO6 > > > together. > > > In the future, there would be a mechanism to control UDP_L4 GSO > > > separately. > > > > > > Test it WIP Qemu https://github.com/daynix/qemu/tree/Dev_USOv2 > > > > > > New types for VirtioNet already on mailing: > > > https://lists.oasis-open.org/archives/virtio-comment/202110/msg00010.html > > > > > > Also, there is a known issue with transmitting packages between two > > > guests. > > > > Could you explain this more? It looks like a bug. (Or any pointer to > > the discussion) > > > > Thanks > > > > > Without hacks with skb's GSO - packages are still segmented on the host's > > > postrouting. > > > > > > Andrew (5): > > > uapi/linux/if_tun.h: Added new offload types for USO4/6. > > > driver/net/tun: Added features for USO. > > > uapi/linux/virtio_net.h: Added USO types. > > > linux/virtio_net.h: Support USO offload in vnet header. > > > drivers/net/virtio_net.c: Added USO support. > > > > > > drivers/net/tap.c | 10 ++++++++-- > > > drivers/net/tun.c | 8 +++++++- > > > drivers/net/virtio_net.c | 19 +++++++++++++++---- > > > include/linux/virtio_net.h | 9 +++++++++ > > > include/uapi/linux/if_tun.h | 2 ++ > > > include/uapi/linux/virtio_net.h | 4 ++++ > > > 6 files changed, 45 insertions(+), 7 deletions(-) > > > > > > -- > > > 2.35.1 > > > > > >
0001-udp-allow-header-check-for-dodgy-GSO_UDP_L4-packets.patch
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