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 */
20static 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(srcp: 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(mask: m, cpu) < nr_cpu_ids &&
40 !cpumask_intersects(src1p: m, cpu_online_mask)) {
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, cpumask: m);
51}
52
53static 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(data: 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 * Complete an eventually pending irq move cleanup. If this
74 * interrupt was moved in hard irq context, then the vectors need
75 * to be cleaned up. It can't wait until this interrupt actually
76 * happens and this CPU was involved.
77 */
78 irq_force_complete_move(desc);
79
80 /*
81 * No move required, if:
82 * - Interrupt is per cpu
83 * - Interrupt is not started
84 * - Affinity mask does not include this CPU.
85 *
86 * Note: Do not check desc->action as this might be a chained
87 * interrupt.
88 */
89 if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) {
90 /*
91 * If an irq move is pending, abort it if the dying CPU is
92 * the sole target.
93 */
94 irq_fixup_move_pending(desc, force_clear: false);
95 return false;
96 }
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, force_clear: 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_intersects(src1p: affinity, cpu_online_mask)) {
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(data: d, dest: affinity, force: false);
133
134 /*
135 * If there are online CPUs in the affinity mask, but they have no
136 * vectors left to make the migration work, try to break the
137 * affinity by migrating to any online CPU.
138 */
139 if (err == -ENOSPC && !irqd_affinity_is_managed(d) && affinity != cpu_online_mask) {
140 pr_debug("IRQ%u: set affinity failed for %*pbl, re-try with online CPUs\n",
141 d->irq, cpumask_pr_args(affinity));
142
143 affinity = cpu_online_mask;
144 brokeaff = true;
145
146 err = irq_do_set_affinity(data: d, dest: affinity, force: false);
147 }
148
149 if (err) {
150 pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
151 d->irq, err);
152 brokeaff = false;
153 }
154
155 if (maskchip && chip->irq_unmask)
156 chip->irq_unmask(d);
157
158 return brokeaff;
159}
160
161/**
162 * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu
163 *
164 * The current CPU has been marked offline. Migrate IRQs off this CPU.
165 * If the affinity settings do not allow other CPUs, force them onto any
166 * available CPU.
167 *
168 * Note: we must iterate over all IRQs, whether they have an attached
169 * action structure or not, as we need to get chained interrupts too.
170 */
171void irq_migrate_all_off_this_cpu(void)
172{
173 struct irq_desc *desc;
174 unsigned int irq;
175
176 for_each_active_irq(irq) {
177 bool affinity_broken;
178
179 desc = irq_to_desc(irq);
180 scoped_guard(raw_spinlock, &desc->lock)
181 affinity_broken = migrate_one_irq(desc);
182
183 if (affinity_broken) {
184 pr_debug_ratelimited("IRQ %u: no longer affine to CPU%u\n",
185 irq, smp_processor_id());
186 }
187 }
188}
189
190static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
191{
192 const struct cpumask *hk_mask;
193
194 if (!housekeeping_enabled(type: HK_TYPE_MANAGED_IRQ))
195 return false;
196
197 hk_mask = housekeeping_cpumask(type: HK_TYPE_MANAGED_IRQ);
198 if (cpumask_subset(src1p: irq_data_get_effective_affinity_mask(d: data), src2p: hk_mask))
199 return false;
200
201 return cpumask_test_cpu(cpu, cpumask: hk_mask);
202}
203
204static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
205{
206 struct irq_data *data = irq_desc_get_irq_data(desc);
207 const struct cpumask *affinity = irq_data_get_affinity_mask(d: data);
208
209 if (!irqd_affinity_is_managed(d: data) || !desc->action ||
210 !irq_data_get_irq_chip(d: data) || !cpumask_test_cpu(cpu, cpumask: affinity))
211 return;
212
213 if (irqd_is_managed_and_shutdown(d: data))
214 irq_startup_managed(desc);
215
216 /*
217 * If the interrupt can only be directed to a single target
218 * CPU then it is already assigned to a CPU in the affinity
219 * mask. No point in trying to move it around unless the
220 * isolation mechanism requests to move it to an upcoming
221 * housekeeping CPU.
222 */
223 if (!irqd_is_single_target(d: data) || hk_should_isolate(data, cpu))
224 irq_set_affinity_locked(data, cpumask: affinity, force: false);
225}
226
227/**
228 * irq_affinity_online_cpu - Restore affinity for managed interrupts
229 * @cpu: Upcoming CPU for which interrupts should be restored
230 */
231int irq_affinity_online_cpu(unsigned int cpu)
232{
233 struct irq_desc *desc;
234 unsigned int irq;
235
236 irq_lock_sparse();
237 for_each_active_irq(irq) {
238 desc = irq_to_desc(irq);
239 scoped_guard(raw_spinlock_irq, &desc->lock)
240 irq_restore_affinity_of_irq(desc, cpu);
241 }
242 irq_unlock_sparse();
243
244 return 0;
245}
246