kernel/irq/cpuhotplug.c

   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_warn_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 }