rr optionally uses CPUID faulting to mask off RDRAND, but this is completely non-critical issue. If this is not available then libraries just need to have envvar switch to disable RDRAND usage. It also uses CPUID faulting for makes traces portable between systems. (if you really need that you can run rr inside VM, and it will work fine)
But core rr functionality works just fine on Zen CPUs, after MSR to disable some determinism-breaking speculations was discovered. These problems were not related to CPUID.
