Re: [PATCH] POWER9 PMU interrupt after idle workaround
From: Madhavan Srinivasan <hidden>
Date: 2017-07-10 12:21:27
On Monday 10 July 2017 11:49 AM, Nicholas Piggin wrote:
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.
Acked-by: Madhavan Srinivasan <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/idle_book3s.S | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)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