Re: Standardizing an MSR or other hypercall to get an RNG seed?

H. Peter Anvin
2014-09-18T14:43:09Z

On 09/18/2014 07:40 AM, KY Srinivasan wrote:
>>
>> The main questions are what MSR index to use and how to detect the
>> presence of the MSR. I've played with two approaches:
>>
>> 1. Use CPUID to detect the presence of this feature. This is very easy for
>> KVM to implement by using a KVM-specific CPUID feature. The problem is
>> that this will necessarily be KVM-specific, as the guest must first probe for
>> KVM and then probe for the KVM feature. I doubt that Hyper-V, for
>> example, wants to claim to be KVM. If we could standardize a non-
>> hypervisor-specific CPUID feature, then this problem would go away.
>
> We would prefer a CPUID feature bit to detect this feature.
>

I guess if we're introducing the concept of pan-OS MSRs we could also
have pan-OS CPUID. The real issue is to get a single non-conflicting
standard.

-hpa