linux-kernel - [GIT PULL] perf events fixes

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Date: Sun, 17 Mar 2024 09:57:38 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>,
	Namhyung Kim <namhyung@...nel.org>,
	linux-perf-users@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] perf events fixes

Linus,

Please pull the latest perf/urgent Git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2024-03-17

   # HEAD: ad8c91282c95f801c37812d59d2d9eba6899b384 perf/x86/amd/core: Avoid register reset when CPU is dead

Two x86 PMU fixes:

 - Work around AMD erratum to filter out bogus LBR stack entries

 - Fix incorrect PMU reset that can result in warnings (or worse)
   during suspend/hibernation.

 Thanks,

	Ingo

------------------>
Sandipan Das (2):
      perf/x86/amd/lbr: Discard erroneous branch entries
      perf/x86/amd/core: Avoid register reset when CPU is dead


 arch/x86/events/amd/core.c | 1 -
 arch/x86/events/amd/lbr.c  | 6 ++++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 69a3b02e50bb..aec16e581f5b 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -604,7 +604,6 @@ static void amd_pmu_cpu_dead(int cpu)
 
 	kfree(cpuhw->lbr_sel);
 	cpuhw->lbr_sel = NULL;
-	amd_pmu_cpu_reset(cpu);
 
 	if (!x86_pmu.amd_nb_constraints)
 		return;
diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c
index eb31f850841a..4a1e600314d5 100644
--- a/arch/x86/events/amd/lbr.c
+++ b/arch/x86/events/amd/lbr.c
@@ -173,9 +173,11 @@ void amd_pmu_lbr_read(void)
 
 		/*
 		 * Check if a branch has been logged; if valid = 0, spec = 0
-		 * then no branch was recorded
+		 * then no branch was recorded; if reserved = 1 then an
+		 * erroneous branch was recorded (see Erratum 1452)
 		 */
-		if (!entry.to.split.valid && !entry.to.split.spec)
+		if ((!entry.to.split.valid && !entry.to.split.spec) ||
+		    entry.to.split.reserved)
 			continue;
 
 		perf_clear_branch_entry_bitfields(br + out);