irqchip/gic-v2m: Handle Multiple MSI base IRQ Alignment

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The PCI Local Bus Specification 3.0 (section 6.8.1.6) allows modifying the
low-order bits of the MSI Message DATA register to encode nr_irqs interrupt
numbers in the log2(nr_irqs) bits for the domain.

The problem arises if the base vector (GICV2m base spi) is not aligned with
nr_irqs; in this case, the low-order log2(nr_irqs) bits from the base
vector conflict with the nr_irqs masking, causing the wrong MSI interrupt
to be identified.

To fix this, use bitmap_find_next_zero_area_off() instead of
bitmap_find_free_region() to align the initial base vector with nr_irqs.

Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/all/20250902091045.220847-1-christian.bruel@foss.st.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Christian Bruel 2025-09-02 11:10:45 +02:00 • committed by Greg Kroah-Hartman

parent 1ba13dde6a

commit 2ca16b41e8

1 changed files with 9 additions and 4 deletions

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drivers/irqchip/irq-gic-v2m.c

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