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 #include <linux/sched/isolation.h> 16 17 #include "internals.h" 18 19 /* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */ 20 static inline bool irq_needs_fixup(struct irq_data *d) 21 { 22 const struct cpumask *m = irq_data_get_effective_affinity_mask(d); 23 unsigned int cpu = smp_processor_id(); 24 25 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK 26 /* 27 * The cpumask_empty() check is a workaround for interrupt chips, 28 * which do not implement effective affinity, but the architecture has 29 * enabled the config switch. Use the general affinity mask instead. 30 */ 31 if (cpumask_empty(m)) 32 m = irq_data_get_affinity_mask(d); 33 34 /* 35 * Sanity check. If the mask is not empty when excluding the outgoing 36 * CPU then it must contain at least one online CPU. The outgoing CPU 37 * has been removed from the online mask already. 38 */ 39 if (cpumask_any_but(m, cpu) < nr_cpu_ids && 40 cpumask_any_and(m, cpu_online_mask) >= nr_cpu_ids) { 41 /* 42 * If this happens then there was a missed IRQ fixup at some 43 * point. Warn about it and enforce fixup. 44 */ 45 pr_warn("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n", 46 cpumask_pr_args(m), d->irq, cpu); 47 return true; 48 } 49 #endif 50 return cpumask_test_cpu(cpu, m); 51 } 52 53 static bool migrate_one_irq(struct irq_desc *desc) 54 { 55 struct irq_data *d = irq_desc_get_irq_data(desc); 56 struct irq_chip *chip = irq_data_get_irq_chip(d); 57 bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d); 58 const struct cpumask *affinity; 59 bool brokeaff = false; 60 int err; 61 62 /* 63 * IRQ chip might be already torn down, but the irq descriptor is 64 * still in the radix tree. Also if the chip has no affinity setter, 65 * nothing can be done here. 66 */ 67 if (!chip || !chip->irq_set_affinity) { 68 pr_debug("IRQ %u: Unable to migrate away\n", d->irq); 69 return false; 70 } 71 72 /* 73 * No move required, if: 74 * - Interrupt is per cpu 75 * - Interrupt is not started 76 * - Affinity mask does not include this CPU. 77 * 78 * Note: Do not check desc->action as this might be a chained 79 * interrupt. 80 */ 81 if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) { 82 /* 83 * If an irq move is pending, abort it if the dying CPU is 84 * the sole target. 85 */ 86 irq_fixup_move_pending(desc, false); 87 return false; 88 } 89 90 /* 91 * Complete an eventually pending irq move cleanup. If this 92 * interrupt was moved in hard irq context, then the vectors need 93 * to be cleaned up. It can't wait until this interrupt actually 94 * happens and this CPU was involved. 95 */ 96 irq_force_complete_move(desc); 97 98 /* 99 * If there is a setaffinity pending, then try to reuse the pending 100 * mask, so the last change of the affinity does not get lost. If 101 * there is no move pending or the pending mask does not contain 102 * any online CPU, use the current affinity mask. 103 */ 104 if (irq_fixup_move_pending(desc, true)) 105 affinity = irq_desc_get_pending_mask(desc); 106 else 107 affinity = irq_data_get_affinity_mask(d); 108 109 /* Mask the chip for interrupts which cannot move in process context */ 110 if (maskchip && chip->irq_mask) 111 chip->irq_mask(d); 112 113 if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { 114 /* 115 * If the interrupt is managed, then shut it down and leave 116 * the affinity untouched. 117 */ 118 if (irqd_affinity_is_managed(d)) { 119 irqd_set_managed_shutdown(d); 120 irq_shutdown_and_deactivate(desc); 121 return false; 122 } 123 affinity = cpu_online_mask; 124 brokeaff = true; 125 } 126 /* 127 * Do not set the force argument of irq_do_set_affinity() as this 128 * disables the masking of offline CPUs from the supplied affinity 129 * mask and therefore might keep/reassign the irq to the outgoing 130 * CPU. 131 */ 132 err = irq_do_set_affinity(d, affinity, false); 133 if (err) { 134 pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n", 135 d->irq, err); 136 brokeaff = false; 137 } 138 139 if (maskchip && chip->irq_unmask) 140 chip->irq_unmask(d); 141 142 return brokeaff; 143 } 144 145 /** 146 * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu 147 * 148 * The current CPU has been marked offline. Migrate IRQs off this CPU. 149 * If the affinity settings do not allow other CPUs, force them onto any 150 * available CPU. 151 * 152 * Note: we must iterate over all IRQs, whether they have an attached 153 * action structure or not, as we need to get chained interrupts too. 154 */ 155 void irq_migrate_all_off_this_cpu(void) 156 { 157 struct irq_desc *desc; 158 unsigned int irq; 159 160 for_each_active_irq(irq) { 161 bool affinity_broken; 162 163 desc = irq_to_desc(irq); 164 raw_spin_lock(&desc->lock); 165 affinity_broken = migrate_one_irq(desc); 166 raw_spin_unlock(&desc->lock); 167 168 if (affinity_broken) { 169 pr_debug_ratelimited("IRQ %u: no longer affine to CPU%u\n", 170 irq, smp_processor_id()); 171 } 172 } 173 } 174 175 static bool hk_should_isolate(struct irq_data *data, unsigned int cpu) 176 { 177 const struct cpumask *hk_mask; 178 179 if (!housekeeping_enabled(HK_FLAG_MANAGED_IRQ)) 180 return false; 181 182 hk_mask = housekeeping_cpumask(HK_FLAG_MANAGED_IRQ); 183 if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask)) 184 return false; 185 186 return cpumask_test_cpu(cpu, hk_mask); 187 } 188 189 static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu) 190 { 191 struct irq_data *data = irq_desc_get_irq_data(desc); 192 const struct cpumask *affinity = irq_data_get_affinity_mask(data); 193 194 if (!irqd_affinity_is_managed(data) || !desc->action || 195 !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity)) 196 return; 197 198 if (irqd_is_managed_and_shutdown(data)) { 199 irq_startup(desc, IRQ_RESEND, IRQ_START_COND); 200 return; 201 } 202 203 /* 204 * If the interrupt can only be directed to a single target 205 * CPU then it is already assigned to a CPU in the affinity 206 * mask. No point in trying to move it around unless the 207 * isolation mechanism requests to move it to an upcoming 208 * housekeeping CPU. 209 */ 210 if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu)) 211 irq_set_affinity_locked(data, affinity, false); 212 } 213 214 /** 215 * irq_affinity_online_cpu - Restore affinity for managed interrupts 216 * @cpu: Upcoming CPU for which interrupts should be restored 217 */ 218 int irq_affinity_online_cpu(unsigned int cpu) 219 { 220 struct irq_desc *desc; 221 unsigned int irq; 222 223 irq_lock_sparse(); 224 for_each_active_irq(irq) { 225 desc = irq_to_desc(irq); 226 raw_spin_lock_irq(&desc->lock); 227 irq_restore_affinity_of_irq(desc, cpu); 228 raw_spin_unlock_irq(&desc->lock); 229 } 230 irq_unlock_sparse(); 231 232 return 0; 233 } 234