linux-kernel - [tip:perf/core] perf/x86/intel: Reset more state in PMU reset

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Date:	Thu, 2 Apr 2015 11:45:06 -0700
From:	tip-bot for Andi Kleen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, ak@...ux.intel.com, linux-kernel@...r.kernel.org,
	hpa@...or.com, peterz@...radead.org, tglx@...utronix.de
Subject: [tip:perf/core] perf/x86/intel: Reset more state in PMU reset

Commit-ID:  8882edf735738c949aba4b65d3ec3453066bab12
Gitweb:     http://git.kernel.org/tip/8882edf735738c949aba4b65d3ec3453066bab12
Author:     Andi Kleen <ak@...ux.intel.com>
AuthorDate: Fri, 27 Feb 2015 09:48:30 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 2 Apr 2015 17:33:16 +0200

perf/x86/intel: Reset more state in PMU reset

The PMU reset code didn't quite keep up with newer PMU features.
Improve it a bit to really reset a modern PMU:

  - Clear all overflow status
  - Clear LBRs and freezing state
  - Disable fixed counters too

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: eranian@...gle.com
Link: http://lkml.kernel.org/r/1425059312-18217-2-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/perf_event_intel.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 6ea61a5..5999460 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1538,6 +1538,18 @@ static void intel_pmu_reset(void)
 	if (ds)
 		ds->bts_index = ds->bts_buffer_base;
 
+	/* Ack all overflows and disable fixed counters */
+	if (x86_pmu.version >= 2) {
+		intel_pmu_ack_status(intel_pmu_get_status());
+		wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0);
+	}
+
+	/* Reset LBRs and LBR freezing */
+	if (x86_pmu.lbr_nr) {
+		update_debugctlmsr(get_debugctlmsr() &
+			~(DEBUGCTLMSR_FREEZE_LBRS_ON_PMI|DEBUGCTLMSR_LBR));
+	}
+
 	local_irq_restore(flags);
 }
 
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