Re: GPF in intel_pmu_lbr_reset() with qemu -cpu host

Gleb Natapov
2014-03-22T08:50:54Z

On Fri, Mar 21, 2014 at 12:04:32PM -0700, Venkatesh Srinivas wrote:
> On Fri, Mar 21, 2014 at 10:46 AM, Peter Wu <peter@lekensteyn.nl> wrote:
[skip]

> When -cpu host is used, qemu/kvm passed the host CPUID F/M/S to the
> guest. intel_pmu_cpu_*() -> intel_pmu_lbr_reset() uses rdmsr() /
> wrmsr(), rather than the safe variants; if KVM does not support the
> particular MSRs in question, you will see a #GP(0) there. See
> https://lkml.org/lkml/2014/3/13/453 for a similar bug other PMU code.
>
When kernel is compiled with guest support all rdmsr()/wrmsr() become _safe(),
so the question for Peter is if his guest kernel has guest support enabled?

--
Gleb.