From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH] powerpc/perf: Fix disabling BHRB and instruction sampling
Date: Thu, 19 Oct 2023 01:34:23 +1000 [thread overview]
Message-ID: <20231018153423.298373-1-npiggin@gmail.com> (raw)
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")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/perf/core-book3s.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 8c1f7def596e..10b946e9c6e7 100644
--- 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 *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();
}
--
2.42.0
next reply other threads:[~2023-10-18 15:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-18 15:34 Nicholas Piggin [this message]
2023-10-27 9:59 ` [PATCH] powerpc/perf: Fix disabling BHRB and instruction sampling Michael Ellerman
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