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

KY Srinivasan
2014-09-18T17:20:47Z

> -----Original Message-----
> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo
> Bonzini
> Sent: Thursday, September 18, 2014 10:18 AM
> To: Nakajima, Jun; KY Srinivasan
> Cc: Mathew John; Theodore Ts'o; John Starks; kvm list; Gleb Natapov; Niels
> Ferguson; Andy Lutomirski; David Hepkin; H. Peter Anvin; Jake Oshins; Linux
> Virtualization
> Subject: Re: Standardizing an MSR or other hypercall to get an RNG seed?
>
> Il 18/09/2014 19:13, Nakajima, Jun ha scritto:
> > In terms of the address for the MSR, I suggest that you choose one
> > from the range between 40000000H - 400000FFH. The SDM (35.1
> > ARCHITECTURAL MSRS) says "All existing and future processors will not
> > implement any features using any MSR in this range." Hyper-V already
> > defines many synthetic MSRs in this range, and I think it would be
> > reasonable for you to pick one for this to avoid a conflict?
>
> KVM is not using any MSR in that range.
>
> However, I think it would be better to have the MSR (and perhaps CPUID)
> outside the hypervisor-reserved ranges, so that it becomes architecturally
> defined. In some sense it is similar to the HYPERVISOR CPUID feature.

Yes, given that we want this to be hypervisor agnostic.

K. Y