1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Generic cpu hotunplug interrupt migration code copied from the 4 * arch/arm implementation 5 * 6 * Copyright (C) Russell King 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 #include <linux/interrupt.h> 13 #include <linux/ratelimit.h> 14 #include <linux/irq.h> 15 16 #include "internals.h" 17 18 /* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */ 19 static inline bool irq_needs_fixup(struct irq_data *d) 20 { 21 const struct cpumask *m = irq_data_get_effective_affinity_mask(d); 22 unsigned int cpu = smp_processor_id(); 23 24 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK 25 /* 26 * The cpumask_empty() check is a workaround for interrupt chips, 27 * which do not implement effective affinity, but the architecture has 28 * enabled the config switch. Use the general affinity mask instead. 29 */ 30 if (cpumask_empty(m)) 31 m = irq_data_get_affinity_mask(d); 32 33 /* 34 * Sanity check. If the mask is not empty when excluding the outgoing 35 * CPU then it must contain at least one online CPU. The outgoing CPU 36 * has been removed from the online mask already. 37 */ 38 if (cpumask_any_but(m, cpu) < nr_cpu_ids && 39 cpumask_any_and(m, cpu_online_mask) >= nr_cpu_ids) { 40 /* 41 * If this happens then there was a missed IRQ fixup at some 42 * point. Warn about it and enforce fixup. 43 */ 44 pr_warn("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n", 45 cpumask_pr_args(m), d->irq, cpu); 46 return true; 47 } 48 #endif 49 return cpumask_test_cpu(cpu, m); 50 } 51 52 static bool migrate_one_irq(struct irq_desc *desc) 53 { 54 struct irq_data *d = irq_desc_get_irq_data(desc); 55 struct irq_chip *chip = irq_data_get_irq_chip(d); 56 bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d); 57 const struct cpumask *affinity; 58 bool brokeaff = false; 59 int err; 60 61 /* 62 * IRQ chip might be already torn down, but the irq descriptor is 63 * still in the radix tree. Also if the chip has no affinity setter, 64 * nothing can be done here. 65 */ 66 if (!chip || !chip->irq_set_affinity) { 67 pr_debug("IRQ %u: Unable to migrate away\n", d->irq); 68 return false; 69 } 70 71 /* 72 * No move required, if: 73 * - Interrupt is per cpu 74 * - Interrupt is not started 75 * - Affinity mask does not include this CPU. 76 * 77 * Note: Do not check desc->action as this might be a chained 78 * interrupt. 79 */ 80 if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) { 81 /* 82 * If an irq move is pending, abort it if the dying CPU is 83 * the sole target. 84 */ 85 irq_fixup_move_pending(desc, false); 86 return false; 87 } 88 89 /* 90 * Complete an eventually pending irq move cleanup. If this 91 * interrupt was moved in hard irq context, then the vectors need 92 * to be cleaned up. It can't wait until this interrupt actually 93 * happens and this CPU was involved. 94 */ 95 irq_force_complete_move(desc); 96 97 /* 98 * If there is a setaffinity pending, then try to reuse the pending 99 * mask, so the last change of the affinity does not get lost. If 100 * there is no move pending or the pending mask does not contain 101 * any online CPU, use the current affinity mask. 102 */ 103 if (irq_fixup_move_pending(desc, true)) 104 affinity = irq_desc_get_pending_mask(desc); 105 else 106 affinity = irq_data_get_affinity_mask(d); 107 108 /* Mask the chip for interrupts which cannot move in process context */ 109 if (maskchip && chip->irq_mask) 110 chip->irq_mask(d); 111 112 if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { 113 /* 114 * If the interrupt is managed, then shut it down and leave 115 * the affinity untouched. 116 */ 117 if (irqd_affinity_is_managed(d)) { 118 irqd_set_managed_shutdown(d); 119 irq_shutdown(desc); 120 return false; 121 } 122 affinity = cpu_online_mask; 123 brokeaff = true; 124 } 125 /* 126 * Do not set the force argument of irq_do_set_affinity() as this 127 * disables the masking of offline CPUs from the supplied affinity 128 * mask and therefore might keep/reassign the irq to the outgoing 129 * CPU. 130 */ 131 err = irq_do_set_affinity(d, affinity, false); 132 if (err) { 133 pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n", 134 d->irq, err); 135 brokeaff = false; 136 } 137 138 if (maskchip && chip->irq_unmask) 139 chip->irq_unmask(d); 140 141 return brokeaff; 142 } 143 144 /** 145 * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu 146 * 147 * The current CPU has been marked offline. Migrate IRQs off this CPU. 148 * If the affinity settings do not allow other CPUs, force them onto any 149 * available CPU. 150 * 151 * Note: we must iterate over all IRQs, whether they have an attached 152 * action structure or not, as we need to get chained interrupts too. 153 */ 154 void irq_migrate_all_off_this_cpu(void) 155 { 156 struct irq_desc *desc; 157 unsigned int irq; 158 159 for_each_active_irq(irq) { 160 bool affinity_broken; 161 162 desc = irq_to_desc(irq); 163 raw_spin_lock(&desc->lock); 164 affinity_broken = migrate_one_irq(desc); 165 raw_spin_unlock(&desc->lock); 166 167 if (affinity_broken) { 168 pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n", 169 irq, smp_processor_id()); 170 } 171 } 172 } 173 174 static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu) 175 { 176 struct irq_data *data = irq_desc_get_irq_data(desc); 177 const struct cpumask *affinity = irq_data_get_affinity_mask(data); 178 179 if (!irqd_affinity_is_managed(data) || !desc->action || 180 !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity)) 181 return; 182 183 if (irqd_is_managed_and_shutdown(data)) { 184 irq_startup(desc, IRQ_RESEND, IRQ_START_COND); 185 return; 186 } 187 188 /* 189 * If the interrupt can only be directed to a single target 190 * CPU then it is already assigned to a CPU in the affinity 191 * mask. No point in trying to move it around. 192 */ 193 if (!irqd_is_single_target(data)) 194 irq_set_affinity_locked(data, affinity, false); 195 } 196 197 /** 198 * irq_affinity_online_cpu - Restore affinity for managed interrupts 199 * @cpu: Upcoming CPU for which interrupts should be restored 200 */ 201 int irq_affinity_online_cpu(unsigned int cpu) 202 { 203 struct irq_desc *desc; 204 unsigned int irq; 205 206 irq_lock_sparse(); 207 for_each_active_irq(irq) { 208 desc = irq_to_desc(irq); 209 raw_spin_lock_irq(&desc->lock); 210 irq_restore_affinity_of_irq(desc, cpu); 211 raw_spin_unlock_irq(&desc->lock); 212 } 213 irq_unlock_sparse(); 214 215 return 0; 216 } 217