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

Paolo Bonzini
2014-09-18T15:58:25Z

Il 18/09/2014 17:44, Andy Lutomirski ha scritto:
> Slight correction: QEMU/KVM has optional support for Hyper-V feature
> enumeration. Ideally the RNG seed mechanism would be enabled by
> default, but I don't know whether the QEMU maintainers would be okay
> with enabling the Hyper-V cpuid mechanism in a default configuration.

Some guests cannot find the KVM leaves at 0x40000100, so it wouldn't be
great. And I also don't know what VMware folks would think, but I think
they would be even less thrilled than me.

Note that even if there is no well-defined CPUID leaf, and the main
detection mechanism is #GP, each hypervisor is free to define a CPUID
bit of its own.

However, if it's going to be an architectural (Intel-defined) MSR, I
think the right place for a feature bit is in the low leaves (like
EAX=7, ECX=0).

Paolo