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: 1cade52 ("powerpc/perf: BHRB control to disable BHRB logic when not used") Cc: [email protected] # v5.9+ Signed-off-by: Nicholas Piggin <[email protected]> Signed-off-by: Michael Ellerman <[email protected]> Link: https://msgid.link/[email protected]
linuxppc · Oct 19, 2023 · a22423e · a22423e
1 parent f9bc9bb
commit a22423e
Showing 1 changed file with 2 additions and 3 deletions.
diff --git 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();
 		}