libvirt users - Jul 2017 - How to make gic_version=3 as defailt to qemu on arm64

Hi

   I'm running Openstack which is installed by using devstack. But it is
not launching VMs.
>From command line with gic_version=3 option it is running. But openstack
glance doesn't have any privilege to specify gic version.

On my ARM64 board gicv2 is not supported, so i want to make gicv3 as
default one to pass to qemu.
Kindly suggest any specific version of vibvirt or patch such that libvirt
should pass gicv3 as default one.

Thanks in Advance
-Vishnu.