Line data    Source code

       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           0 : static inline bool irq_needs_fixup(struct irq_data *d)
      21             : {
      22           0 :         const struct cpumask *m = irq_data_get_effective_affinity_mask(d);
      23           0 :         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           0 :         if (cpumask_empty(m))
      32           0 :                 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           0 :         if (cpumask_any_but(m, cpu) < nr_cpu_ids &&
      40           0 :             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           0 :                 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           0 :                 return true;
      48             :         }
      49             : #endif
      50           0 :         return cpumask_test_cpu(cpu, m);
      51             : }
      52             : 
      53           0 : static bool migrate_one_irq(struct irq_desc *desc)
      54             : {
      55           0 :         struct irq_data *d = irq_desc_get_irq_data(desc);
      56           0 :         struct irq_chip *chip = irq_data_get_irq_chip(d);
      57           0 :         bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d);
      58           0 :         const struct cpumask *affinity;
      59           0 :         bool brokeaff = false;
      60           0 :         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           0 :         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           0 :         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           0 :                 irq_fixup_move_pending(desc, false);
      87           0 :                 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           0 :         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           0 :         if (irq_fixup_move_pending(desc, true))
     105           0 :                 affinity = irq_desc_get_pending_mask(desc);
     106             :         else
     107           0 :                 affinity = irq_data_get_affinity_mask(d);
     108             : 
     109             :         /* Mask the chip for interrupts which cannot move in process context */
     110           0 :         if (maskchip && chip->irq_mask)
     111           0 :                 chip->irq_mask(d);
     112             : 
     113           0 :         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           0 :                 if (irqd_affinity_is_managed(d)) {
     119           0 :                         irqd_set_managed_shutdown(d);
     120           0 :                         irq_shutdown_and_deactivate(desc);
     121           0 :                         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           0 :         err = irq_do_set_affinity(d, affinity, false);
     133           0 :         if (err) {
     134           0 :                 pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
     135             :                                     d->irq, err);
     136             :                 brokeaff = false;
     137             :         }
     138             : 
     139           0 :         if (maskchip && chip->irq_unmask)
     140           0 :                 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           0 : void irq_migrate_all_off_this_cpu(void)
     156             : {
     157           0 :         struct irq_desc *desc;
     158           0 :         unsigned int irq;
     159             : 
     160           0 :         for_each_active_irq(irq) {
     161           0 :                 bool affinity_broken;
     162             : 
     163           0 :                 desc = irq_to_desc(irq);
     164           0 :                 raw_spin_lock(&desc->lock);
     165           0 :                 affinity_broken = migrate_one_irq(desc);
     166           0 :                 raw_spin_unlock(&desc->lock);
     167             : 
     168           0 :                 if (affinity_broken) {
     169           0 :                         pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n",
     170             :                                             irq, smp_processor_id());
     171             :                 }
     172             :         }
     173           0 : }
     174             : 
     175             : static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
     176             : {
     177             :         const struct cpumask *hk_mask;
     178             : 
     179          48 :         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          48 : static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
     190             : {
     191          48 :         struct irq_data *data = irq_desc_get_irq_data(desc);
     192          48 :         const struct cpumask *affinity = irq_data_get_affinity_mask(data);
     193             : 
     194          48 :         if (!irqd_affinity_is_managed(data) || !desc->action ||
     195           0 :             !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
     196          48 :                 return;
     197             : 
     198           0 :         if (irqd_is_managed_and_shutdown(data)) {
     199           0 :                 irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
     200           0 :                 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           0 :         if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu))
     211           0 :                 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           3 : int irq_affinity_online_cpu(unsigned int cpu)
     219             : {
     220           3 :         struct irq_desc *desc;
     221           3 :         unsigned int irq;
     222             : 
     223           3 :         irq_lock_sparse();
     224          51 :         for_each_active_irq(irq) {
     225          48 :                 desc = irq_to_desc(irq);
     226          48 :                 raw_spin_lock_irq(&desc->lock);
     227          48 :                 irq_restore_affinity_of_irq(desc, cpu);
     228          48 :                 raw_spin_unlock_irq(&desc->lock);
     229             :         }
     230           3 :         irq_unlock_sparse();
     231             : 
     232           3 :         return 0;
     233             : }