#!/bin/bash
# libvirt qemu hook: turn GSO and GRO on for the guest's tap.
#
# QEMU leaves them off and sets the tap up after udev has run, so it has to
# happen here. Paired with MTU 9000 they are the difference between 2.5 and
# 14 Gbit/s into the guest; neither helps alone. Tap names come from the domain
# XML on stdin, so the hook never calls virsh, which would deadlock libvirtd.

[ "$2" = started ] || exit 0

for tap in $(grep -oE "<target dev='(vnet|tap|macvtap)[^']*'" | sed "s/.*dev='//; s/'$//"); do
    ethtool -K "$tap" gso on gro on 2>/dev/null
done

exit 0