On Wed, Feb 29, 2012 at 07:00:09PM +0200, Avi Kivity wrote: > On 02/29/2012 03:57 PM, Joerg Roedel wrote: > > It turned out that a performance counter on AMD does not > > count at all when the GO or HO bit is set in the control > > register and SVM is disabled in EFER. > > > > This patch works around this issue by masking out the HO bit > > in the performance counter control register when SVM is not > > enabled. > > > > The GO bit is not touched because it is only set when the > > user wants to count in guest-mode only. So when SVM is > > disabled the counter should not run at all and the > > not-counting is the intended behaviour. > > > > diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c > > index 0397b23..67250a5 100644 > > --- a/arch/x86/kernel/cpu/perf_event_amd.c > > +++ b/arch/x86/kernel/cpu/perf_event_amd.c > > @@ -1,4 +1,5 @@ > > #include <linux/perf_event.h> > > +#include <linux/export.h> > > #include <linux/types.h> > > #include <linux/init.h> > > #include <linux/slab.h> > > @@ -357,7 +358,9 @@ static void amd_pmu_cpu_starting(int cpu) > > struct amd_nb *nb; > > int i, nb_id; > > > > - if (boot_cpu_data.x86_max_cores < 2) > > + cpuc->perf_ctr_virt_mask = AMD_PERFMON_EVENTSEL_HOSTONLY; > > + > > + if (boot_cpu_data.x86_max_cores < 2 || boot_cpu_data.x86 == 0x15) > > return; > > Why this (boot_cpu_data.x86 == 0x15) change? > I think it is related to .cpu_starting callback now available in amd_pmu_f15h where previously it wasn't. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
