Re: [PATCH] perf/x86/intel: Use rdmsrl_safe when initializing RAPL PMU.

From: Andi Kleen
Date: Fri Mar 14 2014 - 12:18:22 EST


> The Intel ISR section for RDMSR seems to say: "Specifying a reserved
> or unimplemented
> MSR address in ECX will also cause a general protection exception".
>
> From a guest's perspective, MSR_RAPL_POWER_UNIT is unimplemented; kvm matches
> this behavior.

MSRs are model specific and defined per model number. If you report a model
number you're expected to implement the MSRs defined for that model number.

AFAIK Xen just reports 0 for unknown MSRs (and I'm surprised KVM doesn't too)

I would suggest to fix KVM.

-Andi
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