[PATCH 4.18 116/158] pinctrl/amd: only handle irq if it is pending and unmasked

From: Greg Kroah-Hartman
Date: Mon Sep 17 2018 - 19:14:57 EST

4.18-stable review patch. If anyone has any objections, please let me know.


From: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>

[ Upstream commit 8bbed1eef001fdfc0ee9595f64cc4f769d265af4 ]

The AMD pinctrl driver demultiplexes GPIO interrupts and fires off their
individual handlers.

If one of these GPIO irqs is configured as a level interrupt, and its
downstream handler is a threaded ONESHOT interrupt, the GPIO interrupt
source is masked by handle_level_irq() until the eventual return of the
threaded irq handler. During this time the level GPIO interrupt status
will still report as high until the actual gpio source is cleared - both
in the individual GPIO interrupt status bit (INTERRUPT_STS_OFF) and in
its corresponding "WAKE_INT_STATUS_REG" bit.

Thus, if another GPIO interrupt occurs during this time,
amd_gpio_irq_handler() will see that the (masked-and-not-yet-cleared)
level irq is still pending and incorrectly call its handler again.

To fix this, have amd_gpio_irq_handler() check for both interrupts status
and mask before calling generic_handle_irq().

Note: Is it possible that this bug was the source of the interrupt storm
on Ryzen when using chained interrupts before commit ba714a9c1dea85
("pinctrl/amd: Use regular interrupt instead of chained")?

Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/pinctrl/pinctrl-amd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/pinctrl/pinctrl-amd.c
+++ b/drivers/pinctrl/pinctrl-amd.c
@@ -552,7 +552,8 @@ static irqreturn_t amd_gpio_irq_handler(
/* Each status bit covers four pins */
for (i = 0; i < 4; i++) {
regval = readl(regs + i);
- if (!(regval & PIN_IRQ_PENDING))
+ if (!(regval & PIN_IRQ_PENDING) ||
+ !(regval & BIT(INTERRUPT_MASK_OFF)))
irq = irq_find_mapping(gc->irq.domain, irqnr + i);