Commit d802057c authored Apr 05, 2022 by Marc Zyngier Committed by Thomas Gleixner Apr 10, 2022

genirq/msi: Shutdown managed interrupts with unsatifiable affinities



When booting with maxcpus=<small number>, interrupt controllers
such as the GICv3 ITS may not be able to satisfy the affinity of
some managed interrupts, as some of the HW resources are simply
not available.

The same thing happens when loading a driver using managed interrupts
while CPUs are offline.

In order to deal with this, do not try to activate such interrupt
if there is no online CPU capable of handling it. Instead, place
it in shutdown state. Once a capable CPU shows up, it will be
activated.

Reported-by: John Garry <john.garry@huawei.com>
Reported-by: David Decotigny <ddecotig@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/20220405185040.206297-2-maz@kernel.org

parent 31231092

kernel/irq/msi.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -818,6 +818,21 @@ static int msi_init_virq(struct irq_domain *domain, int virq, unsigned int vflag
		irqd_clr_can_reserve(irqd);
		if (vflags & VIRQ_NOMASK_QUIRK)
		irqd_set_msi_nomask_quirk(irqd);

		/*
		* If the interrupt is managed but no CPU is available to
		* service it, shut it down until better times. Note that
		* we only do this on the !RESERVE path as x86 (the only
		* architecture using this flag) deals with this in a
		* different way by using a catch-all vector.
		*/
		if ((vflags & VIRQ_ACTIVATE) &&
		irqd_affinity_is_managed(irqd) &&
		!cpumask_intersects(irq_data_get_affinity_mask(irqd),
		cpu_online_mask)) {
		irqd_set_managed_shutdown(irqd);
		return 0;
		}
		}

		if (!(vflags & VIRQ_ACTIVATE))