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

Andi Kleen
2014-03-14T13:56:54Z

On Fri, Mar 14, 2014 at 09:44:29AM +0100, Peter Zijlstra wrote:
> On Thu, Mar 13, 2014 at 12:36:26PM -0700, Venkatesh Srinivas wrote:
> > CPUs which should support the RAPL counters according to
> > Family/Model/Stepping may still issue #GP when attempting to access
> > the RAPL MSRs. This may happen when Linux is running under KVM and
> > we are passing-through host F/M/S data, for example. Use rdmsrl_safe
> > to first access the RAPL_POWER_UNIT MSR; if this fails, do not
> > attempt to use this PMU.
>
> This kvm thing is getting tedious :-(

It sounds bogus to me too, VMs are supposed to return 0
on reading unknown MSRs, no #GP.

-Andi

--
ak@linux.intel.com -- Speaking for myself only