Re: [RFC PATCH v2] perf: honouring the cpuid for number of fixed counters in hypervisors

[Peter Zijlstra]

On Fri, Oct 21, 2016 at 01:18:59AM -0700, Imre Palik wrote:
> +++ b/arch/x86/events/intel/core.c
> @@ -3607,10 +3607,14 @@ __init int intel_pmu_init(void)
>  
>       /*
>        * Quirk: v2 perfmon does not report fixed-purpose events, so
> +      * assume at least 3 events, when not running in a hypervisor:
>        */
> +     if (version > 1) {
> +             if (static_cpu_has(X86_FEATURE_HYPERVISOR))
> +                     x86_pmu.num_counters_fixed = 
> edx.split.num_counters_fixed;
> +             else
> +                     x86_pmu.num_counters_fixed = 
> max((int)edx.split.num_counters_fixed, 3);
> +     }


I made that:

        /*
         * Quirk: v2 perfmon does not report fixed-purpose events, so
+        * assume at least 3 events, when not running in a hypervisor:
         */
+       if (version > 1) {
+               int assume = 3 * !boot_cpu_has(X86_FEATURE_HYPERVISOR);
+
+               x86_pmu.num_counters_fixed =
+                       max((int)edx.split.num_counters_fixed, assume);
+       }
 

Thanks!