irqchip/gic-v5: Defer default SPI and LPI IAFFID programming

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SPI and LPI interrupts do not have an architected default value for their
IAFFID (interrupt affinity ID) - the property that determines an IRQ
affinity.

Current code awkwardly tries to set a default IAFFID value corresponding
to the logical cpu executing the gicv5_hwirq_init() function at SPI/LPI
allocation time.

There are two issues with this approach:

- gicv5_hwirq_init() is called in preemptible context and current code
  uses smp_processor_id() to check the logical cpu executing the function.
  Whilst that's harmless, it can spit a splat on DEBUG_PREEMPT kernels
- Setting the default SPI/LPI IAFFID to the one belonging to the cpu
  executing the IRQ allocation is a completely arbitrary choice

It is saner to remove the SPI/LPI IAFFID set-up in the SPI/LPI domain IRQ
allocation code and flag SPI/LPI irqchips as IRQCHIP_AFFINITY_PRE_STARTUP
so that the SPI/LPI affinity is initialized by IRQ core to a sane value
before an IRQ is started up using the respective irq_chip
irq_set_affinity() callback.

Fixes: 5cb1b6dab2 ("irqchip/gic-v5: Add GICv5 IRS/SPI support")
Fixes: 0f01013258 ("irqchip/gic-v5: Add GICv5 LPI/IPI support")
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260812-gicv5-7-2-fixes-v1-7-3743e82c69a4@kernel.org

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Lorenzo Pieralisi 2026-08-12 11:10:35 +02:00 • committed by Thomas Gleixner

parent 9dfcc21872

commit a1ee1a1ca7

1 changed files with 4 additions and 14 deletions

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drivers/irqchip/irq-gic-v5.c

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