Qemu 8.0 and libvirt 9.3.0 added support for qemu emulated igb network device. So we can  extend the hw_vif_model image property to support the igb value. Then we can add a conditional support for that vif model in the libvirt driver.

This emulated NIC model actually supports SR-IOV, so it is super useful for functional testing openstack SR-IOV support without the need for real hardware e.g. PCI passthrough in nova, SR-IOV ports support in nova and neutron, SR-IOV backed load balancer in octavia.

[1]https://blueprints.launchpad.net/nova/+spec/igb-vif-model

[2]https://review.opendev.org/q/topic:%22bp/igb-vif-model%22