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
  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_and_deactivate(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 }