Re: linux 3.13 guest crash with -cpu host

Paolo Bonzini
2014-02-03T14:07:41Z

Il 03/02/2014 15:06, Michael S. Tsirkin ha scritto:
>> Linux seems to be trying to read IA32_PERF_CAPABILITIES without checking the
>> PDCM flag (CPUID[1].ECX[15]).
>>
>> I can't see why this wasn't crashing before, though. That code seems to be old.
>>
>> * v2 and above have a perf capabilities MSR
>> */
>> if (version > 1) {
>> u64 capabilities;
>>
>> rdmsrl(MSR_IA32_PERF_CAPABILITIES, capabilities);
>> x86_pmu.intel_cap.capabilities = capabilities;
>> }
>>
>> Where does the "v2 and above have a perf capabilities MSR" claim in the code
>> come from?
>
>
> But why doesn't it crash on baremetal?
> Probably baremetal simply returns 0 or something.
> Let me try ..

Because KVM doesn't implement the MSR, but your baremetal likely does.

Paolo