linux-kernel - [PATCH 11/12] perf/x86-ibs: Catch spurious interrupts after stopping ibs

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Date:	Mon, 2 Apr 2012 20:19:17 +0200
From:	Robert Richter <robert.richter@....com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Robert Richter <robert.richter@....com>
Subject: [PATCH 11/12] perf/x86-ibs: Catch spurious interrupts after stopping ibs

After disabling IBS there could be still incomming NMIs with samples
that even have the valid bit cleared. Mark all this NMIs as handled to
avoid spurious interrupt messages.

Signed-off-by: Robert Richter <robert.richter@....com>
---
 arch/x86/kernel/cpu/perf_event_amd_ibs.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_amd_ibs.c b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
index 35a35be..b44aa63 100644
--- a/arch/x86/kernel/cpu/perf_event_amd_ibs.c
+++ b/arch/x86/kernel/cpu/perf_event_amd_ibs.c
@@ -475,11 +475,13 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
 	u64 *buf, *config, period;
 
 	if (!test_bit(IBS_STARTED, pcpu->state)) {
-		/* Catch spurious interrupts after stopping IBS: */
-		if (!test_and_clear_bit(IBS_STOPPING, pcpu->state))
-			return 0;
-		rdmsrl(perf_ibs->msr, *ibs_data.regs);
-		return (*ibs_data.regs & perf_ibs->valid_mask) ? 1 : 0;
+		/*
+		 * Catch spurious interrupts after stopping IBS: After
+		 * disabling IBS there could be still incomming NMIs
+		 * with samples that even have the valid bit cleared.
+		 * Mark all this NMIs as handled.
+		 */
+		return test_and_clear_bit(IBS_STOPPING, pcpu->state) ? 1 : 0;
 	}
 
 	msr = hwc->config_base;
-- 
1.7.8.4


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