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 <npig...@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
--
2.11.0
