Re: [PATCH 1/2] perf: ignore LBR and offcore_rsp.

Peter Zijlstra
2014-06-23T09:19:57Z

On Thu, Jun 19, 2014 at 10:52:52AM -0700, Andi Kleen wrote:
> Andi Kleen <andi@firstfloor.org> writes:
> >>
> >>> Signed-off-by: Kan Liang <kan.liang@intel.com>
> >>
> >> And here I thought that Andi was of the opinion that if you set CPUID to
> >> indicate a particular CPU you had better also handle all its MSRs.
> >
> > Yes, philosophically that would be the right way,
> > but we needed a short term fix to stop things from crashing, and that
> > was the simplest.
>
> I should add there is another reason for this patch now,
> and doing it in perf instead of somewhere else
> (this should probably go into the description).
>
> With PT on enabling LBR can #GP. So perf needs to handle
> this case without crashing. This can happen independently
> of any hypervisors.

WTH is a PT?