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powerpc/perf: Fix disabling BHRB and instruction sampling 

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: 1cade527f6 ("powerpc/perf: BHRB control to disable BHRB logic when not used")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231018153423.298373-1-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicholas Piggin 2023-10-19 01:34:23 +10:00 committed by Greg Kroah-Hartman
parent 4cb064f617
commit bee4f891fe
1 changed files with 2 additions and 3 deletions
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5
arch/powerpc/perf/core-book3s.c
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@ -1371,8 +1371,7 @@ static void power_pmu_disable(struct pmu *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 *pmu)
* instruction sampling or BHRB.
*/
if (val != mmcra) {
mtspr(SPRN_MMCRA, mmcra);
mtspr(SPRN_MMCRA, val);
mb();
isync();
}