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

Web:        https://git.kernel.org/torvalds/c/6cc3f91bf69fc8c1719704607474f9b9df56f348
Commit:     6cc3f91bf69fc8c1719704607474f9b9df56f348
Parent:     5c11d1e52d996749897a8616860b18a084c894f0
Refname:    refs/heads/master
Author:     Nicholas Piggin <[email protected]>
AuthorDate: Sat Feb 3 17:17:50 2018 +1000
Committer:  Michael Ellerman <[email protected]>
CommitDate: Thu Feb 8 23:56:10 2018 +1100

    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 <[email protected]>
    Reviewed-by: Madhavan Srinivasan <[email protected]>
    Signed-off-by: Michael Ellerman <[email protected]>
---
 arch/powerpc/include/asm/hw_irq.h    | 12 +++++++++++-
 arch/powerpc/kernel/exceptions-64e.S |  2 ++
 arch/powerpc/kernel/exceptions-64s.S |  6 +++---
 3 files changed, 16 insertions(+), 4 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
@@ -29,6 +29,16 @@
 #define PACA_IRQ_HMI		0x20
 #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
  */
@@ -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();
 }
 
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index ee832d344a5a..9b6e653e501a 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -943,6 +943,8 @@ kernel_dbg_exc:
 /*
  * An interrupt came in while soft-disabled; We mark paca->irq_happened
  * accordingly and if the interrupt is level sensitive, we hard disable
+ * hard disable (full_mask) corresponds to PACA_IRQ_MUST_HARD_MASK, so
+ * keep these in synch.
  */
 
 .macro masked_interrupt_book3e paca_irq full_mask
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 243d072a225a..3ac87e53b3da 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1426,7 +1426,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
  *   triggered and won't automatically refire.
  * - If it was a HMI we return immediately since we handled it in realmode
  *   and it won't refire.
- * - else we hard disable and return.
+ * - Else it is one of PACA_IRQ_MUST_HARD_MASK, so hard disable and return.
  * This is called with r10 containing the value to OR to the paca field.
  */
 #define MASKED_INTERRUPT(_H)				\
@@ -1441,8 +1441,8 @@ masked_##_H##interrupt:					\
 	ori	r10,r10,0xffff;				\
 	mtspr	SPRN_DEC,r10;				\
 	b	MASKED_DEC_HANDLER_LABEL;		\
-1:	andi.	r10,r10,(PACA_IRQ_DBELL|PACA_IRQ_HMI);	\
-	bne	2f;					\
+1:	andi.	r10,r10,PACA_IRQ_MUST_HARD_MASK;	\
+	beq	2f;					\
 	mfspr	r10,SPRN_##_H##SRR1;			\
 	xori	r10,r10,MSR_EE; /* clear MSR_EE */	\
 	mtspr	SPRN_##_H##SRR1,r10;			\
--
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html