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x86/vector: Add a sanity check to prevent IRQ2 allocations 

To prevent another incidental removal of the IRQ2 ignore logic in the
IO/APIC code going unnoticed add a sanity check. Add some commentry at the
other place which ignores IRQ2 while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210318192819.795280387@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-03-18 20:26:48 +01:00
parent a5e13c6df0
commit 9a98bc2cf0
1 changed files with 13 additions and 0 deletions
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13
arch/x86/kernel/apic/vector.c
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@ -543,6 +543,14 @@ static int x86_vector_alloc_irqs(struct irq_domain *domain, unsigned int virq,
if ((info->flags & X86_IRQ_ALLOC_CONTIGUOUS_VECTORS) && nr_irqs > 1)
return -ENOSYS;
/*
* Catch any attempt to touch the cascade interrupt on a PIC
* equipped system.
*/
if (WARN_ON_ONCE(info->flags & X86_IRQ_ALLOC_LEGACY &&
virq == PIC_CASCADE_IR))
return -EINVAL;
for (i = 0; i < nr_irqs; i++) {
irqd = irq_domain_get_irq_data(domain, virq + i);
BUG_ON(!irqd);
@ -745,6 +753,11 @@ void __init lapic_assign_system_vectors(void)
/* Mark the preallocated legacy interrupts */
for (i = 0; i < nr_legacy_irqs(); i++) {
/*
* Don't touch the cascade interrupt. It's unusable
* on PIC equipped machines. See the large comment
* in the IO/APIC code.
*/
if (i != PIC_CASCADE_IR)
irq_matrix_assign(vector_matrix, ISA_IRQ_VECTOR(i));
}