RHEL 9 are being compiled for the x86_64-v2 architecture which is
newer than the qemu default of qemu64. Nehalem is apparently the
oldest model that works for x86_64-v2 and is expected to work on
Intel and AMD cpus with kvm or qemu.
See devstack change [0].
[0]: Ibd6e11b59f3c8655bc60ace7383a08458b2177f2
Change-Id: Ia0a3620bae21984933756331bb5937ce681d3237