[net-next,0/4] virtio-net: avoid XDP and _F_GUEST_CSUM

Message

Heng Qi June 19, 2023, 10:57 a.m. UTC

virtio-net needs to clear the VIRTIO_NET_F_GUEST_CSUM feature when
loading XDP. The main reason for doing this is because
VIRTIO_NET_F_GUEST_CSUM allows to receive packets marked as
VIRTIO_NET_HDR_F_NEEDS_CSUM. Such packets are not compatible with
XDP programs, because we cannot guarantee that the csum_{start, offset}
fields are correct after XDP modifies the packets.

There is also an existing problem, in the same host vm-vm (eg
[vm]<->[ovs vhost-user]<->[vm]) scenario, loading XDP will cause packet loss.

To solve the above problems, we have discussed in the [1] proposal, and
now try to solve it through the method of reprobing fields suggested
by Jason.

[1] https://lists.oasis-open.org/archives/virtio-dev/202305/msg00318.html

Heng Qi (4):
  virtio-net: a helper for probing the pseudo-header checksum
  virtio-net: reprobe csum related fields for skb passed by XDP
  virtio-net: virtio-net: support coexistence of XDP and _F_GUEST_CSUM
  virtio-net: remove F_GUEST_CSUM check for XDP loading

 drivers/net/virtio_net.c | 173 +++++++++++++++++++++++++++++++++++----
 1 file changed, 158 insertions(+), 15 deletions(-)