Re: [tip:perf/core] perf/x86: Add an MSR PMU driver

Andy Lutomirski
2015-08-06T15:30:31Z

On Thu, Aug 6, 2015 at 8:21 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Aug 04, 2015 at 08:39:27PM +0000, Liang, Kan wrote:
> - default:
> - err = -ENOTSUPP;
> + if (!msr[i].test() || rdmsrl_safe(msr[i].msr, &val))
> + msr[i].attr = NULL;

IIRC rdmsrl_safe literally never fails under QEMU TCG, and I'm not
entirely sure what happens under KVM if emulation kicks in. It might
pay to keep the model check for the non-architectural stuff, or at
least check for a nonzero return value.

--Andy