Patch "powerpc/perf: Fix disabling BHRB and instruction sampling" has been added to the 6.1-stable tree

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

    powerpc/perf: Fix disabling BHRB and instruction sampling

to the 6.1-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:
     powerpc-perf-fix-disabling-bhrb-and-instruction-sampling.patch
and it can be found in the queue-6.1 subdirectory.

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


>From ea142e590aec55ba40c5affb4d49e68c713c63dc Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Thu, 19 Oct 2023 01:34:23 +1000
Subject: powerpc/perf: Fix disabling BHRB and instruction sampling

From: Nicholas Piggin <npiggin@xxxxxxxxx>

commit ea142e590aec55ba40c5affb4d49e68c713c63dc upstream.

When the PMU is disabled, MMCRA is not updated to disable BHRB and
instruction sampling. This can lead to those features remaining enabled,
which can slow down a real or emulated CPU.

Fixes: 1cade527f6e9 ("powerpc/perf: BHRB control to disable BHRB logic when not used")
Cc: stable@xxxxxxxxxxxxxxx # v5.9+
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://msgid.link/20231018153423.298373-1-npiggin@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/powerpc/perf/core-book3s.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1371,8 +1371,7 @@ static void power_pmu_disable(struct pmu
 		/*
 		 * Disable instruction sampling if it was enabled
 		 */
-		if (cpuhw->mmcr.mmcra & MMCRA_SAMPLE_ENABLE)
-			val &= ~MMCRA_SAMPLE_ENABLE;
+		val &= ~MMCRA_SAMPLE_ENABLE;
 
 		/* Disable BHRB via mmcra (BHRBRD) for p10 */
 		if (ppmu->flags & PPMU_ARCH_31)
@@ -1383,7 +1382,7 @@ static void power_pmu_disable(struct pmu
 		 * instruction sampling or BHRB.
 		 */
 		if (val != mmcra) {
-			mtspr(SPRN_MMCRA, mmcra);
+			mtspr(SPRN_MMCRA, val);
 			mb();
 			isync();
 		}


Patches currently in stable-queue which might be from npiggin@xxxxxxxxx are

queue-6.1/powerpc-perf-fix-disabling-bhrb-and-instruction-sampling.patch



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