[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH for-4.19 5/9] x86/irq: limit interrupt movement done by fixup_irqs()
The current check used in fixup_irqs() to decide whether to move around interrupts is based on the affinity mask, but such mask can have all bits set, and hence is unlikely to be a subset of the input mask. For example if an interrupt has an affinity mask of all 1s, any input to fixup_irqs() that's not an all set CPU mask would cause that interrupt to be shuffled around unconditionally. What fixup_irqs() care about is evacuating interrupts from CPUs not set on the input CPU mask, and for that purpose it should check whether the interrupt is assigned to a CPU not present in the input mask. Assume that ->arch.cpu_mask is a subset of the ->affinity mask, and keep the current logic that resets the ->affinity mask if the interrupt has to be shuffled around. While there also adjust the comment as to the purpose of fixup_irqs(). Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> --- Changes since v1: - Do not AND ->arch.cpu_mask with cpu_online_map. - Keep using cpumask_subset(). - Integrate into bigger series. --- xen/arch/x86/include/asm/irq.h | 2 +- xen/arch/x86/irq.c | 9 +++++++-- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/include/asm/irq.h b/xen/arch/x86/include/asm/irq.h index 80a3aa7a88b9..b7dc75d0acbd 100644 --- a/xen/arch/x86/include/asm/irq.h +++ b/xen/arch/x86/include/asm/irq.h @@ -156,7 +156,7 @@ void free_domain_pirqs(struct domain *d); int map_domain_emuirq_pirq(struct domain *d, int pirq, int emuirq); int unmap_domain_pirq_emuirq(struct domain *d, int pirq); -/* Reset irq affinities to match the given CPU mask. */ +/* Evacuate interrupts assigned to CPUs not present in the input CPU mask. */ void fixup_irqs(const cpumask_t *mask, bool verbose); void fixup_eoi(void); diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c index 9716e00e873b..1b7127090377 100644 --- a/xen/arch/x86/irq.c +++ b/xen/arch/x86/irq.c @@ -2525,7 +2525,7 @@ static int __init cf_check setup_dump_irqs(void) } __initcall(setup_dump_irqs); -/* Reset irq affinities to match the given CPU mask. */ +/* Evacuate interrupts assigned to CPUs not present in the input CPU mask. */ void fixup_irqs(const cpumask_t *mask, bool verbose) { unsigned int irq; @@ -2582,7 +2582,12 @@ void fixup_irqs(const cpumask_t *mask, bool verbose) &cpu_online_map); } - if ( !desc->action || cpumask_subset(desc->affinity, mask) ) + /* + * Avoid shuffling the interrupt around as long as current target CPUs + * are a subset of the input mask. What fixup_irqs() cares about is + * evacuating interrupts from CPUs not in the input mask. + */ + if ( !desc->action || cpumask_subset(desc->arch.cpu_mask, mask) ) { spin_unlock(&desc->lock); continue; -- 2.44.0
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