When disable_irq_nosync for an interrupt is called from within its
interrupt handler, this interrupt is only marked as disabled with the
intention to mask it when it triggers again.
The AIC hardware however automatically masks the interrupt when it is read.
aic_irq_eoi then unmasks it again if it's not disabled *and* not masked.
This results in a state mismatch between the hardware state and the
state kept in irq_data: The hardware interrupt is masked but
IRQD_IRQ_MASKED is not set. Any further calls to unmask_irq will directly
return and the interrupt can never be enabled again.
Fix this by keeping the hardware and irq_data state in sync by unmasking in
aic_irq_eoi if and only if the irq_data state also assumes the interrupt to
be unmasked.
Fixes: 76cde26394 ("irqchip/apple-aic: Add support for the Apple Interrupt Controller")
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Acked-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210812100942.17206-1-sven@svenpeter.dev
The CPUs in the Apple M1 SoC partially implement a virtual GICv3
CPU interface, although one that is incapable of HW deactivation
of interrupts, nor masking the maintenance interrupt.
Advertise the support to KVM.
Signed-off-by: Marc Zyngier <maz@kernel.org>
This is the root interrupt controller used on Apple ARM SoCs such as the
M1. This irqchip driver performs multiple functions:
* Handles both IRQs and FIQs
* Drives the AIC peripheral itself (which handles IRQs)
* Dispatches FIQs to downstream hard-wired clients (currently the ARM
timer).
* Implements a virtual IPI multiplexer to funnel multiple Linux IPIs
into a single hardware IPI
Reviewed-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Hector Martin <marcan@marcan.st>
