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 */
irq_needs_fixup(struct irq_data * d)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
migrate_one_irq(struct irq_desc * desc)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 * 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, 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, 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 */
irq_migrate_all_off_this_cpu(void)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
hk_should_isolate(struct irq_data * data,unsigned int cpu)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_TYPE_MANAGED_IRQ))
180 return false;
181
182 hk_mask = housekeeping_cpumask(HK_TYPE_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
irq_restore_affinity_of_irq(struct irq_desc * desc,unsigned int cpu)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 */
irq_affinity_online_cpu(unsigned int cpu)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