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authorGleb Natapov <gleb@redhat.com>2012-08-09 11:52:34 +0300
committerThomas Gleixner <tglx@linutronix.de>2012-08-13 19:01:04 +0200
commit26a4f3c08de49c1437a7b7f97693cf22d8c31656 (patch)
tree3f1bafcd6e9cac2dfb0d26236d79fcc9ba970938 /arch
parentcb37af77124e8532e6ae3f9ca332593ba423b5f8 (diff)
downloadlinux-26a4f3c08de49c1437a7b7f97693cf22d8c31656.tar.bz2
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 <dsahern@gmail.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120809085234.GI3341@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel.c10
1 files changed, 9 insertions, 1 deletions
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;
}