Nova is assuming 'host-model' for KVM/QEMU setup.
On AArch64 it results in "libvirtError: unsupported configuration: CPU
mode 'host-model' for aarch64 kvm domain on aarch64 host is not
supported by hypervisor" message.
AArch64 lacks 'host-model' support because neither libvirt nor QEMU
are able to tell what the host CPU model exactly is. And there is no
CPU description code for ARM(64) at this point.
So instead we fallback to 'host-passthrough' to get VM instances
running. This will completely break live migration, *unless* all the
Compute nodes (running libvirtd) have *identical* CPUs.
Small summary: https://marcin.juszkiewicz.com.pl/2018/01/04/today-i-was-fighting-with-nova-no-idea-who-won/
Closes-bug: #1741230
Co-authored-by: Kevin Zhao <Kevin.Zhao@arm.com>
Co-authored-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Change-Id: Iafb5f1790d68489db73b9f0549333108c6426a00