diff options
| author | Nicholas Piggin | 2017-07-10 16:19:38 +1000 |
|---|---|---|
| committer | Michael Ellerman | 2017-07-18 11:45:47 +1000 |
| commit | 101dd590a7fa37954540cf3149a1c502c0acc524 (patch) | |
| tree | 0d25f21a5c4d5f3a3592de7e82249422065fed92 /arch/powerpc/kernel/idle_book3s.S | |
| parent | a70b487b07cf4201bc6702e7f646fa593b23009f (diff) | |
powerpc/perf: Avoid spurious PMU interrupts after idle
POWER9 DD2 can see spurious PMU interrupts after state-loss idle in
some conditions.
A solution is to save and reload MMCR0 over state-loss idle.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Tested-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/idle_book3s.S')
| -rw-r--r-- | arch/powerpc/kernel/idle_book3s.S | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 5adb390e773b..516ebef905c0 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -30,6 +30,7 @@ * Use unused space in the interrupt stack to save and restore * registers for winkle support. */ +#define _MMCR0 GPR0 #define _SDR1 GPR3 #define _PTCR GPR3 #define _RPR GPR4 @@ -272,6 +273,14 @@ power_enter_stop: b pnv_wakeup_noloss .Lhandle_esl_ec_set: + /* + * POWER9 DD2 can incorrectly set PMAO when waking up after a + * state-loss idle. Saving and restoring MMCR0 over idle is a + * workaround. + */ + mfspr r4,SPRN_MMCR0 + std r4,_MMCR0(r1) + /* * Check if the requested state is a deep idle state. */ @@ -450,10 +459,14 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300) pnv_restore_hyp_resource_arch300: /* * Workaround for POWER9, if we lost resources, the ERAT - * might have been mixed up and needs flushing. + * might have been mixed up and needs flushing. We also need + * to reload MMCR0 (see comment above). */ blt cr3,1f PPC_INVALIDATE_ERAT + ld r1,PACAR1(r13) + ld r4,_MMCR0(r1) + mtspr SPRN_MMCR0,r4 1: /* * POWER ISA 3. Use PSSCR to determine if we |