Nakajima, Jun
2014-Sep-18 17:13 UTC
Standardizing an MSR or other hypercall to get an RNG seed?
On Thu, Sep 18, 2014 at 9:36 AM, KY Srinivasan <kys at microsoft.com> wrote:> > I am copying other Hyper-V engineers to this discussion. >Thanks, K.Y. 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? -- Jun Intel Open Source Technology Center
Paolo Bonzini
2014-Sep-18 17:17 UTC
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. Paolo
Jake Oshins
2014-Sep-18 17:20 UTC
Standardizing an MSR or other hypercall to get an RNG seed?
That certainly sound reasonable to me. How do you see discovery of that working? Thanks, Jake Oshins -----Original Message----- From: Paolo Bonzini [mailto:paolo.bonzini at 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. Paolo
KY Srinivasan
2014-Sep-18 17:20 UTC
Standardizing an MSR or other hypercall to get an RNG seed?
> -----Original Message----- > From: Paolo Bonzini [mailto:paolo.bonzini at 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
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