Patch "x86/irq: Prevent force migration of irqs which are not in the vector domain" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

x86/irq: Prevent force migration of irqs which are not in the vector domain

to the 4.7-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:
x86-irq-prevent-force-migration-of-irqs-which-are-not-in-the-vector-domain.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mika Westerberg <[email protected]>
Date: Mon, 3 Oct 2016 13:17:08 +0300
Subject: x86/irq: Prevent force migration of irqs which are not in the vector domain

From: Mika Westerberg <[email protected]>

commit db91aa793ff984ac048e199ea1c54202543952fe upstream.

When a CPU is about to be offlined we call fixup_irqs() that resets IRQ affinities related to the CPU in question. The same thing is also done when the system is suspended to S-states like S3 (mem).

For each IRQ we try to complete any on-going move regardless whether the IRQ is actually part of x86_vector_domain. For each IRQ descriptor we fetch its chip_data, assume it is of type struct apic_chip_data and manipulate it by clearing old_domain mask etc. For irq_chips that are not part of the x86_vector_domain, like those created by various GPIO drivers, will find their chip_data being changed unexpectly.

Below is an example where GPIO chip owned by pinctrl-sunrisepoint.c gets corrupted after resume:

  # cat /sys/kernel/debug/gpio
  gpiochip0: GPIOs 360-511, parent: platform/INT344B:00, INT344B:00:
   gpio-511 (                    |sysfs               ) in  hi

  # rtcwake -s10 -mmem
  <10 seconds passes>

  # cat /sys/kernel/debug/gpio
  gpiochip0: GPIOs 360-511, parent: platform/INT344B:00, INT344B:00:
   gpio-511 (                    |sysfs               ) in  ?

Note '?' in the output. It means the struct gpio_chip ->get function is NULL whereas before suspend it was there.

Fix this by first checking that the IRQ belongs to x86_vector_domain before we try to use the chip_data as struct apic_chip_data.

---
 arch/x86/kernel/apic/vector.c |   23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

@@ -661,11 +661,28 @@ void irq_complete_move(struct irq_cfg *c
  */
 void irq_force_complete_move(struct irq_desc *desc)
 {
-	struct irq_data *irqdata = irq_desc_get_irq_data(desc);
-	struct apic_chip_data *data = apic_chip_data(irqdata);
-	struct irq_cfg *cfg = data ? &data->cfg : NULL;
+	struct irq_data *irqdata;
+	struct apic_chip_data *data;
+	struct irq_cfg *cfg;
 	unsigned int cpu;
 
+	/*
+	 * The function is called for all descriptors regardless of which
+	 * irqdomain they belong to. For example if an IRQ is provided by
+	 * an irq_chip as part of a GPIO driver, the chip data for that
+	 * descriptor is specific to the irq_chip in question.
+	 *
+	 * Check first that the chip_data is what we expect
+	 * (apic_chip_data) before touching it any further.
+	 */
+	irqdata = irq_domain_get_irq_data(x86_vector_domain,
+					  irq_desc_get_irq(desc));
+	if (!irqdata)
+		return;
+
+	data = apic_chip_data(irqdata);
+	cfg = data ? &data->cfg : NULL;
+
 	if (!cfg)
 		return;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/x86-irq-prevent-force-migration-of-irqs-which-are-not-in-the-vector-domain.patch