irq_set_vcpu_affinity(9)

💖 irq_set_vcpu_affinity(9) 💖

okay so bestie, welcome to the Kernel API Manual, section 9 — this one's all about irq_set_vcpu_affinity, and no cap it's a whole vibe.

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✨ NAME ✨

irq_set_vcpu_affinity — set vcpu affinity for the interrupt 🎀

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🌸 SYNOPSIS 🌸

int irq_set_vcpu_affinity (unsigned int irq , void *vcpu_info );

like, that's the whole signature, look at her go 💅

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🦋 ARGUMENTS 🦋

• irq — the interrupt number you're setting affinity for. this is the main character of the operation ngl 🔥
• vcpu_info — vCPU specific data, or a pointer to a percpu array of vCPU specific data for percpu_devid interrupts. two moods, one pointer, iykyk ✨

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💜 DESCRIPTION 💜

so what she does: this function uses that vCPU specific data to set the vCPU affinity for an irq. the vCPU specific data is passed in from outside, like from KVM — it doesn't magically appear, someone hands it over 🫶

one example code path is literally this, and it's giving relay race:

KVM -> IOMMU -> irq_set_vcpu_affinity

KVM hands it off, IOMMU carries the baton, and irq_set_vcpu_affinity crosses the finish line. slay 💅

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🌈 SEE ALSO 🌈

Kernel file ./kernel/irq/manage.c — and like, the whole friend group:

• synchronize_hardirq(9)
• synchronize_irq(9)
• irq_can_set_affinity(9)
• irq_can_set_affinity_usr(9)
• irq_set_thread_affinity(9)
• irq_affinity_schedule_notify_work(9)
• irq_update_affinity_desc(9)
• irq_set_affinity(9)
• irq_force_affinity(9)
• irq_set_affinity_notifier(9)
• disable_irq_nosync(9)
• disable_irq(9)
• disable_hardirq(9)
• disable_nmi_nosync(9)
• enable_irq(9)
• enable_nmi(9)
• irq_set_irq_wake(9)
• irq_wake_thread(9)
• free_irq(9)
• request_threaded_irq(9)
• request_any_context_irq(9)
• request_nmi(9)
• irq_percpu_is_enabled(9)
• free_percpu_irq(9)
• request_percpu_irq_affinity(9)
• request_percpu_nmi(9)
• prepare_percpu_nmi(9)
• teardown_percpu_nmi(9)
• irq_get_irqchip_state(9)
• irq_set_irqchip_state(9)
• irq_has_action(9)
• irq_check_status_bit(9)

the way that's literally the entire irq squad 😭💖

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okay that's the page!! this one came straight out of ./kernel/irq, dated October 2026, so shoutout to the source for keeping it iconic — go read it, it ate 🌟👑💀✨