Re: linux 3.13 guest crash with -cpu host

Peter Zijlstra
2014-02-03T14:28:50Z

On Mon, Feb 03, 2014 at 03:26:42PM +0100, Peter Zijlstra wrote:
> On Mon, Feb 03, 2014 at 03:19:18PM +0100, Paolo Bonzini wrote:
> > Il 03/02/2014 15:12, Peter Zijlstra ha scritto:
> > >>> But why doesn't it crash on baremetal?
> > >>> Probably baremetal simply returns 0 or something.
> > >>> Let me try ..
> > >The claim "v2 and above have FEATURE_PDCM" is in fact true for real
> > >hardware.
> > >
> > >If it didn't the rdmsr() would have generated an exception and we'd have
> > >crashed just like your virtual thingy did.
> >
> > Right, and the virt thingy has no PEBS, so there is no correct value that we
> > could return from the MSR. That's why the CPUID bit is zero.
>
> There's more than PEBS in there, there's also the LBR format (which you
> obviously also don't have)

On that.. LBR is purely model based, what do you guys do with those
MSRs?