This is a note to let you know that I've just added the patch titled
powerpc/64: Fix __check_irq_replay missing decrementer interrupt
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-64-fix-__check_irq_replay-missing-decrementer-interrupt.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3db40c312c2c1eb2187c5731102fa8ff380e6e40 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Tue, 1 Aug 2017 23:59:28 +1000
Subject: powerpc/64: Fix __check_irq_replay missing decrementer interrupt
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit 3db40c312c2c1eb2187c5731102fa8ff380e6e40 upstream.
If the decrementer wraps again and de-asserts the decrementer
exception while hard-disabled, __check_irq_replay() has a test to
notice the wrap when interrupts are re-enabled.
The decrementer check must be done when clearing the PACA_IRQ_HARD_DIS
flag, not when the PACA_IRQ_DEC flag is tested. Previously this worked
because the decrementer interrupt was always the first one checked
after clearing the hard disable flag, but HMI check was moved ahead of
that, which introduced this bug.
This can cause a missed decrementer interrupt if we soft-disable
interrupts then take an HMI which is recorded in irq_happened, then
hard-disable interrupts for > 4s to wrap the decrementer.
Fixes: e0e0d6b7390b ("powerpc/64: Replay hypervisor maintenance interrupt first")
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/irq.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -146,6 +146,19 @@ notrace unsigned int __check_irq_replay(
/* Clear bit 0 which we wouldn't clear otherwise */
local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
+ if (happened & PACA_IRQ_HARD_DIS) {
+ /*
+ * We may have missed a decrementer interrupt if hard disabled.
+ * Check the decrementer register in case we had a rollover
+ * while hard disabled.
+ */
+ if (!(happened & PACA_IRQ_DEC)) {
+ if (decrementer_check_overflow()) {
+ local_paca->irq_happened |= PACA_IRQ_DEC;
+ happened |= PACA_IRQ_DEC;
+ }
+ }
+ }
/*
* Force the delivery of pending soft-disabled interrupts on PS3.
@@ -171,7 +184,7 @@ notrace unsigned int __check_irq_replay(
* in case we also had a rollover while hard disabled
*/
local_paca->irq_happened &= ~PACA_IRQ_DEC;
- if ((happened & PACA_IRQ_DEC) || decrementer_check_overflow())
+ if (happened & PACA_IRQ_DEC)
return 0x900;
/* Finally check if an external interrupt happened */
Patches currently in stable-queue which might be from npiggin@xxxxxxxxx are
queue-4.9/powerpc-64-fix-__check_irq_replay-missing-decrementer-interrupt.patch