I think the right place for this question is the ovirt users mailing list. Added.
Hi All
We are looking into setting up a highly scalable and HA Ovirt infrastructure but I see only some CPU's are supported. Is this only for th Hypervisors or for the entire cluster?
Not sure what difference you have in mind. In general those are for guest CPUs, in general KVM capabilities are a bit behind the real hardware and gets added to oVirt as we add the relevant qemu-kvm having them, e.g. right now the “best” x86_64 Intel CPU is Skylake-Server and you can run it on any RHEL/CentOS 7.6 supported hw capable of at least that, e.g. any Cascade Lake.