From a22423ea7c8aa93beb6f325d0b07580880509c04 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Thu, 19 Oct 2023 01:34:23 +1000 Subject: [PATCH] powerpc/perf: Fix disabling BHRB and instruction sampling 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@vger.kernel.org # v5.9+ Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20231018153423.298373-1-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 8c1f7def596e4..10b946e9c6e75 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(); }