1 files changed, 22 insertions, 3 deletions

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index dff6623804c2..332954cccece 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -1945,6 +1945,14 @@ static __initconst const u64 knl_hw_cache_extra_regs
  * intel_bts events don't coexist with intel PMU's BTS events because of
  * x86_add_exclusive(x86_lbr_exclusive_lbr); there's no need to keep them
  * disabled around intel PMU's event batching etc, only inside the PMI handler.
+ *
+ * Avoid PEBS_ENABLE MSR access in PMIs.
+ * The GLOBAL_CTRL has been disabled. All the counters do not count anymore.
+ * It doesn't matter if the PEBS is enabled or not.
+ * Usually, the PEBS status are not changed in PMIs. It's unnecessary to
+ * access PEBS_ENABLE MSR in disable_all()/enable_all().
+ * However, there are some cases which may change PEBS status, e.g. PMI
+ * throttle. The PEBS_ENABLE should be updated where the status changes.
  */
 static void __intel_pmu_disable_all(void)
 {
@@ -1954,13 +1962,12 @@ static void __intel_pmu_disable_all(void)
 
 	if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask))
 		intel_pmu_disable_bts();
-
-	intel_pmu_pebs_disable_all();
 }
 
 static void intel_pmu_disable_all(void)
 {
 	__intel_pmu_disable_all();
+	intel_pmu_pebs_disable_all();
 	intel_pmu_lbr_disable_all();
 }
 
@@ -1968,7 +1975,6 @@ static void __intel_pmu_enable_all(int added, bool pmi)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 
-	intel_pmu_pebs_enable_all();
 	intel_pmu_lbr_enable_all(pmi);
 	wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL,
 			x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask);
@@ -1986,6 +1992,7 @@ static void __intel_pmu_enable_all(int added, bool pmi)
 
 static void intel_pmu_enable_all(int added)
 {
+	intel_pmu_pebs_enable_all();
 	__intel_pmu_enable_all(added, false);
 }
 
@@ -2374,9 +2381,21 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 * PEBS overflow sets bit 62 in the global status register
 	 */
 	if (__test_and_clear_bit(62, (unsigned long *)&status)) {
+		u64 pebs_enabled = cpuc->pebs_enabled;
+
 		handled++;
 		x86_pmu.drain_pebs(regs);
 		status &= x86_pmu.intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI;
+
+		/*
+		 * PMI throttle may be triggered, which stops the PEBS event.
+		 * Although cpuc->pebs_enabled is updated accordingly, the
+		 * MSR_IA32_PEBS_ENABLE is not updated. Because the
+		 * cpuc->enabled has been forced to 0 in PMI.
+		 * Update the MSR if pebs_enabled is changed.
+		 */
+		if (pebs_enabled != cpuc->pebs_enabled)
+			wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled);
 	}
 
 	/*