From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756371Ab0ICJOG (ORCPT ); Fri, 3 Sep 2010 05:14:06 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:35530 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756283Ab0ICJOC convert rfc822-to-8bit (ORCPT ); Fri, 3 Sep 2010 05:14:02 -0400 Subject: [PATCH] perf, x86: Disable perf if the BIOS got its grubby paws on the PMU From: Peter Zijlstra To: Ingo Molnar , Stephane Eranian , "robert.richter" Cc: Linus Torvalds , LKML , Arjan Van De Ven , "H. Peter Anvin" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Fri, 03 Sep 2010 11:13:47 +0200 Message-ID: <1283505227.1783.224.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Disable all of perf if we find any active PMCs on boot. It has been reported that some BIOSes access the PMU, for obscure things better done by the OS. Come down hard on this practice and fully disable the PMU. [ Boot tested on a westmere system with a sane BIOS -- I don't actually have an affected system to test this on. ] Signed-off-by: Peter Zijlstra --- Robert, do you know if any AMD system BIOSes carry similar Feat^H^H^H^HFailureAdd? arch/x86/kernel/cpu/perf_event_intel.c | 35 ++++++++++++++++++++++++++++++++ 1 files changed, 35 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index ee05c90..6849653 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -923,6 +923,19 @@ static void intel_clovertown_quirks(void) x86_pmu.pebs_constraints = NULL; } +static void print_BIOS_fail(void) +{ + printk(KERN_ERR "\n"); + printk(KERN_ERR "=============================================\n"); + printk(KERN_ERR "It appears the BIOS is actively using the PMU\n"); + printk(KERN_ERR "this avoids Linux from using it, please de- \n"); + printk(KERN_ERR "activate this BIOS feature or request a BIOS \n"); + printk(KERN_ERR "update from your vendor. \n"); + printk(KERN_ERR "=============================================\n"); + + memset(&x86_pmu, 0, sizeof(x86_pmu)); +} + static __init int intel_pmu_init(void) { union cpuid10_edx edx; @@ -930,6 +943,8 @@ static __init int intel_pmu_init(void) unsigned int unused; unsigned int ebx; int version; + u64 val; + int i; if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) { switch (boot_cpu_data.x86) { @@ -968,6 +983,26 @@ static __init int intel_pmu_init(void) x86_pmu.num_counters_fixed = max((int)edx.split.num_counters_fixed, 3); /* + * Check to see if the BIOS enabled any of the counters, if so + * complain and bail. + */ + for (i = 0; i < x86_pmu.num_counters; i++) { + rdmsrl(x86_pmu.eventsel + i, val); + if (val & ARCH_PERFMON_EVENTSEL_ENABLE) { + print_BIOS_fail(); + return -EBUSY; + } + } + + for (i = 0; i < x86_pmu.num_counters_fixed; i++) { + rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR_CTRL, val); + if (val & (0x03 << i*4)) { + print_BIOS_fail(); + return -EBUSY; + } + } + + /* * v2 and above have a perf capabilities MSR */ if (version > 1) {