Merge branch 'veth-gro'

Paolo Abeni  says:

====================
veth: allow GRO even without XDP

This series allows the user-space to enable GRO/NAPI on a veth
device even without attaching an XDP program.

It does not change the default veth behavior (no NAPI, no GRO),
except that the GRO feature bit on top of this series will be
effectively off by default on veth devices. Note that currently
the GRO bit is on by default, but GRO never takes place in
absence of XDP.

On top of this series, setting the GRO feature bit enables NAPI
and allows the GRO to take place. The TSO features on the peer
device are preserved.

The main goal is improving UDP forwarding performances for
containers in a typical virtual network setup:

(container) veth -> veth peer -> bridge/ovs -> vxlan -> NIC

Enabling the NAPI threaded mode, GRO the NETIF_F_GRO_UDP_FWD
feature on the veth peer improves the UDP stream performance
with not void netfilter configuration by 2x factor with no
measurable overhead for TCP traffic: some heuristic ensures
that TCP will not go through the additional NAPI/GRO layer.

Some self-tests are added to check the expected behavior in
the default configuration, with XDP and with plain GRO enabled.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>