On Thu, Dec 20, 2018 at 01:30:15PM -0500, Willem de Bruijn wrote: > On Wed, Dec 19, 2018 at 5:44 PM Willem de Bruijn > <willemdebruijn.ker...@gmail.com> wrote: > > > > 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. > > I was wrong. This was a deliberate choice. See below. Will leave as is. > > The other change is not really important enough on its, so I'll just > send a v2 of this patch. > > One additional change, show LRO as enabled if it is active for any protocol > (as opposed to only for all protocols), so that we can truly disable it in all > cases.
That makes sense. > " > commit e59ff2c49ae16e1d179de679aca81405829aee6c > Author: Jason Wang <jasow...@redhat.com> > Date: Thu Nov 22 14:36:30 2018 +0800 > > virtio-net: disable guest csum during XDP set > > We don't disable VIRTIO_NET_F_GUEST_CSUM if XDP was set. This means we > can receive partial csumed packets with metadata kept in the > vnet_hdr. This may have several side effects: > > - It could be overridden by header adjustment, thus is might be not > correct after XDP processing. > - There's no way to pass such metadata information through > XDP_REDIRECT to another driver. > - XDP does not support checksum offload right now. > > So simply disable guest csum if possible in this the case of XDP. > "
