From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: linux 3.13 guest crash with -cpu host
Date: Mon, 03 Feb 2014 15:07:33 +0100
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References: <20140202205930.GA2157@redhat.com> <20140203125828.GH2221@otherpad.lan.raisama.net> <20140203140601.GA24944@redhat.com>
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Cc: kvm@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Eduardo Habkost <ehabkost@redhat.com>
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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