Commit ea142e59 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

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: 1cade527 ("powerpc/perf: BHRB control to disable BHRB logic when not used")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231018153423.298373-1-npiggin@gmail.com
parent f01b0edd

arch/powerpc/perf/core-book3s.c

+2 −3
Original line number Diff line number Diff line
@@ -1371,7 +1371,6 @@ 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;



		/* Disable BHRB via mmcra (BHRBRD) for p10 */
@@ -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();

		}