Commit-ID: c9b08884c9c98929ec2d8abafd78e89062d01ee7 Gitweb: http://git.kernel.org/tip/c9b08884c9c98929ec2d8abafd78e89062d01ee7 Author: Peter Zijlstra <[email protected]> AuthorDate: Mon, 3 Feb 2014 14:29:03 +0100 Committer: Thomas Gleixner <[email protected]> CommitDate: Fri, 21 Feb 2014 22:09:01 +0100
perf/x86: Correctly use FEATURE_PDCM The current code simply assumes Intel Arch PerfMon v2+ to have the IA32_PERF_CAPABILITIES MSR; the SDM specifies that we should check CPUID[1].ECX[15] (aka, FEATURE_PDCM) instead. This was found by KVM which implements v2+ but didn't provide the capabilities MSR. Change the code to DTRT; KVM will also implement the MSR and return 0. Cc: [email protected] Reported-by: "Michael S. Tsirkin" <[email protected]> Suggested-by: Eduardo Habkost <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/kernel/cpu/perf_event_intel.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 698ae77..aa333d9 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -2308,10 +2308,7 @@ __init int intel_pmu_init(void) if (version > 1) x86_pmu.num_counters_fixed = max((int)edx.split.num_counters_fixed, 3); - /* - * v2 and above have a perf capabilities MSR - */ - if (version > 1) { + if (boot_cpu_has(X86_FEATURE_PDCM)) { u64 capabilities; rdmsrl(MSR_IA32_PERF_CAPABILITIES, capabilities); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
