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

From: David Ahern
Date: Fri Mar 14 2014 - 12:58:30 EST


On 3/14/14, 10:17 AM, Andi Kleen wrote:
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.

I believe ignore_msrs parameter to kvm handles that.

David

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