powerpc/64s: Fix may_hard_irq_enable() for PMI soft masking

The soft IRQ masking code has to hard-disable interrupts in cases
where the exception is not cleared by the masked handler. External
interrupts used this approach for soft masking. Now recently PMU
interrupts do the same thing.

The soft IRQ masking code additionally allowed for interrupt handlers
to hard-enable interrupts after soft-disabling them. The idea is to
allow PMU interrupts through to profile interrupt handlers.

So when interrupts are being replayed when there is a pending
interrupt that requires hard-disabling, there is a test to prevent
those handlers from hard-enabling them if there is a pending external
interrupt. may_hard_irq_enable() handles this.

After f442d00480 ("powerpc/64s: Add support to mask perf interrupts
and replay them"), may_hard_irq_enable() could prematurely enable
MSR[EE] when a PMU exception exists, which would result in the
interrupt firing again while masked, and MSR[EE] being disabled again.

I haven't seen that this could cause a serious problem, but it's
more consistent to handle these soft-masked interrupts in the same
way. So introduce a define for all types of interrupts that require
MSR[EE] masking in their soft-disable handlers, and use that in
may_hard_irq_enable().

Fixes: f442d004806e ("powerpc/64s: Add support to mask perf interrupts and replay them")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 11 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index 88e5e8f17e98..855e17d158b1 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -30,6 +30,16 @@
 #define PACA_IRQ_PMI		0x40
 
 /*
+ * Some soft-masked interrupts must be hard masked until they are replayed
+ * (e.g., because the soft-masked handler does not clear the exception).
+ */
+#ifdef CONFIG_PPC_BOOK3S
+#define PACA_IRQ_MUST_HARD_MASK	(PACA_IRQ_EE|PACA_IRQ_PMI)
+#else
+#define PACA_IRQ_MUST_HARD_MASK	(PACA_IRQ_EE)
+#endif
+
+/*
  * flags for paca->irq_soft_mask
  */
 #define IRQS_ENABLED		0
@@ -244,7 +254,7 @@ static inline bool lazy_irq_pending(void)
 static inline void may_hard_irq_enable(void)
 {
 	get_paca()->irq_happened &= ~PACA_IRQ_HARD_DIS;
-	if (!(get_paca()->irq_happened & PACA_IRQ_EE))
+	if (!(get_paca()->irq_happened & PACA_IRQ_MUST_HARD_MASK))
 		__hard_irq_enable();
 }