From: Gleb Natapov Date: Thu, 9 Aug 2012 08:52:34 +0000 (+0300) Subject: perf/x86: disable PEBS on a guest entry. X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=26a4f3c08de4;p=openwrt%2Fstaging%2Fblogic.git perf/x86: disable PEBS on a guest entry. If PMU counter has PEBS enabled it is not enough to disable counter on a guest entry since PEBS memory write can overshoot guest entry and corrupt guest memory. Disabling PEBS during guest entry solves the problem. Tested-by: David Ahern Signed-off-by: Gleb Natapov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20120809085234.GI3341@redhat.com Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 382366977d4c..7f2739e03e79 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1522,8 +1522,16 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr) arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL; arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask; arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask; + /* + * If PMU counter has PEBS enabled it is not enough to disable counter + * on a guest entry since PEBS memory write can overshoot guest entry + * and corrupt guest memory. Disabling PEBS solves the problem. + */ + arr[1].msr = MSR_IA32_PEBS_ENABLE; + arr[1].host = cpuc->pebs_enabled; + arr[1].guest = 0; - *nr = 1; + *nr = 2; return arr; }