On Wed, Dec 19, 2018 at 5:32 PM Willem de Bruijn <willemdebruijn.ker...@gmail.com> wrote: > > From: Willem de Bruijn <will...@google.com> > > Virtio-net devices negotiate LRO support with the host. > Display the initially negotiated state with ethtool -k. > > Also allow configuring it with ethtool -K, reusing the existing > virtnet_set_guest_offloads helper that disables LRO for XDP. > > Virtio-net negotiates TSO4 and TSO6 separately, but ethtool does not > distinguish between the two. In the unlikely legacy case where the > host only supports one of the two, maintain the current state. > > RTNL is held while calling virtnet_set_features, same as on the path > from virtnet_xdp_set. > > Tested: > Verified that large-receive-offload is "off [fixed]" when not > negotiated during initial probe and "on" otherwise. > > Measured packet size when scp-ing a large file to the guest with > nstat (IpExtInOctets / IpInDelivers). Verified that packet size > exceeds MTU only if ethtool -k shows LRO and/or GRO as enabled. > > Signed-off-by: Willem de Bruijn <will...@google.com>
Two comments for the review: 1. Current drivers show LRO as disabled even if it is negotiated at probe. That is arguably a bug. In which case I can split this patch into - a net patch to advertise the initially negotiated value through dev->feature - a net-next patch to configure it with ndo_set_features. 2. virtnet_clear_guest_offloads disables all guest_offloads, including VIRTIO_NET_F_GUEST_CSUM. That seems undesirable? The feature is a prerequisite for LRO, but not the other way around. This applies equally to the xdp and ethtool paths, so would be another separate net patch.
