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: 1cade527f6e9 ("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>
/*
* 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)
* instruction sampling or BHRB.
*/
if (val != mmcra) {
- mtspr(SPRN_MMCRA, mmcra);
+ mtspr(SPRN_MMCRA, val);
mb();
isync();
}