// SPDX-License-Identifier: GPL-2.0 /* * Generic cpu hotunplug interrupt migration code copied from the * arch/arm implementation * * Copyright (C) Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/interrupt.h> #include <linux/ratelimit.h> #include <linux/irq.h> #include <linux/sched/isolation.h> #include "internals.h" /* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */ static inline bool irq_needs_fixup(struct irq_data *d) { const struct cpumask *m = irq_data_get_effective_affinity_mask(d); unsigned int cpu = smp_processor_id(); #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK /* * The cpumask_empty() check is a workaround for interrupt chips, * which do not implement effective affinity, but the architecture has * enabled the config switch. Use the general affinity mask instead. */ if (cpumask_empty(m)) m = irq_data_get_affinity_mask(d); /* * Sanity check. If the mask is not empty when excluding the outgoing * CPU then it must contain at least one online CPU. The outgoing CPU * has been removed from the online mask already. */ if (cpumask_any_but(m, cpu) < nr_cpu_ids && cpumask_any_and(m, cpu_online_mask) >= nr_cpu_ids) { /* * If this happens then there was a missed IRQ fixup at some * point. Warn about it and enforce fixup. */ pr_warn("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n", cpumask_pr_args(m), d->irq, cpu); return true; } #endif return cpumask_test_cpu(cpu, m); } static bool migrate_one_irq(struct irq_desc *desc) { struct irq_data *d = irq_desc_get_irq_data(desc); struct irq_chip *chip = irq_data_get_irq_chip(d); bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d); const struct cpumask *affinity; bool brokeaff = false; int err; /* * IRQ chip might be already torn down, but the irq descriptor is * still in the radix tree. Also if the chip has no affinity setter, * nothing can be done here. */ if (!chip || !chip->irq_set_affinity) { pr_debug("IRQ %u: Unable to migrate away\n", d->irq); return false; } /* * No move required, if: * - Interrupt is per cpu * - Interrupt is not started * - Affinity mask does not include this CPU. * * Note: Do not check desc->action as this might be a chained * interrupt. */ if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) { /* * If an irq move is pending, abort it if the dying CPU is * the sole target. */ irq_fixup_move_pending(desc, false); return false; } /* * Complete an eventually pending irq move cleanup. If this * interrupt was moved in hard irq context, then the vectors need * to be cleaned up. It can't wait until this interrupt actually * happens and this CPU was involved. */ irq_force_complete_move(desc); /* * If there is a setaffinity pending, then try to reuse the pending * mask, so the last change of the affinity does not get lost. If * there is no move pending or the pending mask does not contain * any online CPU, use the current affinity mask. */ if (irq_fixup_move_pending(desc, true)) affinity = irq_desc_get_pending_mask(desc); else affinity = irq_data_get_affinity_mask(d); /* Mask the chip for interrupts which cannot move in process context */ if (maskchip && chip->irq_mask) chip->irq_mask(d); if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { /* * If the interrupt is managed, then shut it down and leave * the affinity untouched. */ if (irqd_affinity_is_managed(d)) { irqd_set_managed_shutdown(d); irq_shutdown_and_deactivate(desc); return false; } affinity = cpu_online_mask; brokeaff = true; } /* * Do not set the force argument of irq_do_set_affinity() as this * disables the masking of offline CPUs from the supplied affinity * mask and therefore might keep/reassign the irq to the outgoing * CPU. */ err = irq_do_set_affinity(d, affinity, false); if (err) { pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n", d->irq, err); brokeaff = false; } if (maskchip && chip->irq_unmask) chip->irq_unmask(d); return brokeaff; } /** * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu * * The current CPU has been marked offline. Migrate IRQs off this CPU. * If the affinity settings do not allow other CPUs, force them onto any * available CPU. * * Note: we must iterate over all IRQs, whether they have an attached * action structure or not, as we need to get chained interrupts too. */ void irq_migrate_all_off_this_cpu(void) { struct irq_desc *desc; unsigned int irq; for_each_active_irq(irq) { bool affinity_broken; desc = irq_to_desc(irq); raw_spin_lock(&desc->lock); affinity_broken = migrate_one_irq(desc); raw_spin_unlock(&desc->lock); if (affinity_broken) { pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n", irq, smp_processor_id()); } } } static bool hk_should_isolate(struct irq_data *data, unsigned int cpu) { const struct cpumask *hk_mask; if (!housekeeping_enabled(HK_FLAG_MANAGED_IRQ)) return false; hk_mask = housekeeping_cpumask(HK_FLAG_MANAGED_IRQ); if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask)) return false; return cpumask_test_cpu(cpu, hk_mask); } static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu) { struct irq_data *data = irq_desc_get_irq_data(desc); const struct cpumask *affinity = irq_data_get_affinity_mask(data); if (!irqd_affinity_is_managed(data) || !desc->action || !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity)) return; if (irqd_is_managed_and_shutdown(data)) { irq_startup(desc, IRQ_RESEND, IRQ_START_COND); return; } /* * If the interrupt can only be directed to a single target * CPU then it is already assigned to a CPU in the affinity * mask. No point in trying to move it around unless the * isolation mechanism requests to move it to an upcoming * housekeeping CPU. */ if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu)) irq_set_affinity_locked(data, affinity, false); } /** * irq_affinity_online_cpu - Restore affinity for managed interrupts * @cpu: Upcoming CPU for which interrupts should be restored */ int irq_affinity_online_cpu(unsigned int cpu) { struct irq_desc *desc; unsigned int irq; irq_lock_sparse(); for_each_active_irq(irq) { desc = irq_to_desc(irq); raw_spin_lock_irq(&desc->lock); irq_restore_affinity_of_irq(desc, cpu); raw_spin_unlock_irq(&desc->lock); } irq_unlock_sparse(); return 0; }