Patch "perf/x86: Fix exclusion of BTS and LBR for Goldmont" has been added to the 4.8-stable tree

Patch "perf/x86: Fix exclusion of BTS and LBR for Goldmont" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    perf/x86: Fix exclusion of BTS and LBR for Goldmont

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-x86-fix-exclusion-of-bts-and-lbr-for-goldmont.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b0c1ef52959582144bbea9a2b37db7f4c9e399f7 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@linux.intel.com>
Date: Thu, 8 Dec 2016 16:14:17 -0800
Subject: perf/x86: Fix exclusion of BTS and LBR for Goldmont

From: Andi Kleen <ak@linux.intel.com>

commit b0c1ef52959582144bbea9a2b37db7f4c9e399f7 upstream.

An earlier patch allowed enabling PT and LBR at the same
time on Goldmont. However it also allowed enabling BTS and LBR
at the same time, which is still not supported. Fix this by
bypassing the check only for PT.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: alexander.shishkin@intel.com
Cc: kan.liang@intel.com
Fixes: ccbebba4c6bf ("perf/x86/intel/pt: Bypass PT vs. LBR exclusivity if the core supports it")
Link: http://lkml.kernel.org/r/20161209001417.4713-1-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/events/core.c       |    8 ++++++--
 arch/x86/events/perf_event.h |    2 +-
 2 files changed, 7 insertions(+), 3 deletions(-)

--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -364,7 +364,11 @@ int x86_add_exclusive(unsigned int what)
 {
 	int i;
 
-	if (x86_pmu.lbr_pt_coexist)
+	/*
+	 * When lbr_pt_coexist we allow PT to coexist with either LBR or BTS.
+	 * LBR and BTS are still mutually exclusive.
+	 */
+	if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt)
 		return 0;
 
 	if (!atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what])) {
@@ -387,7 +391,7 @@ fail_unlock:
 
 void x86_del_exclusive(unsigned int what)
 {
-	if (x86_pmu.lbr_pt_coexist)
+	if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt)
 		return;
 
 	atomic_dec(&x86_pmu.lbr_exclusive[what]);
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -601,7 +601,7 @@ struct x86_pmu {
 	u64		lbr_sel_mask;		   /* LBR_SELECT valid bits */
 	const int	*lbr_sel_map;		   /* lbr_select mappings */
 	bool		lbr_double_abort;	   /* duplicated lbr aborts */
-	bool		lbr_pt_coexist;		   /* LBR may coexist with PT */
+	bool		lbr_pt_coexist;		   /* (LBR|BTS) may coexist with PT */
 
 	/*
 	 * Intel PT/LBR/BTS are exclusive


Patches currently in stable-queue which might be from ak@linux.intel.com are

queue-4.8/perf-x86-fix-exclusion-of-bts-and-lbr-for-goldmont.patch