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(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
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(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
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(d, affinity, 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		raw_spin_lock(&desc->lock);
181		affinity_broken = migrate_one_irq(desc);
182		raw_spin_unlock(&desc->lock);
183
184		if (affinity_broken) {
185			pr_debug_ratelimited("IRQ %u: no longer affine to CPU%u\n",
186					    irq, smp_processor_id());
187		}
188	}
189}
190
191static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
192{
193	const struct cpumask *hk_mask;
194
195	if (!housekeeping_enabled(HK_TYPE_MANAGED_IRQ))
196		return false;
197
198	hk_mask = housekeeping_cpumask(HK_TYPE_MANAGED_IRQ);
199	if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask))
200		return false;
201
202	return cpumask_test_cpu(cpu, hk_mask);
203}
204
205static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
206{
207	struct irq_data *data = irq_desc_get_irq_data(desc);
208	const struct cpumask *affinity = irq_data_get_affinity_mask(data);
209
210	if (!irqd_affinity_is_managed(data) || !desc->action ||
211	    !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
212		return;
213
214	/*
215	 * Don't restore suspended interrupts here when a system comes back
216	 * from S3. They are reenabled via resume_device_irqs().
217	 */
218	if (desc->istate & IRQS_SUSPENDED)
219		return;
220
221	if (irqd_is_managed_and_shutdown(data))
222		irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
223
224	/*
225	 * If the interrupt can only be directed to a single target
226	 * CPU then it is already assigned to a CPU in the affinity
227	 * mask. No point in trying to move it around unless the
228	 * isolation mechanism requests to move it to an upcoming
229	 * housekeeping CPU.
230	 */
231	if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu))
232		irq_set_affinity_locked(data, affinity, false);
233}
234
235/**
236 * irq_affinity_online_cpu - Restore affinity for managed interrupts
237 * @cpu:	Upcoming CPU for which interrupts should be restored
238 */
239int irq_affinity_online_cpu(unsigned int cpu)
240{
241	struct irq_desc *desc;
242	unsigned int irq;
243
244	irq_lock_sparse();
245	for_each_active_irq(irq) {
246		desc = irq_to_desc(irq);
247		raw_spin_lock_irq(&desc->lock);
248		irq_restore_affinity_of_irq(desc, cpu);
249		raw_spin_unlock_irq(&desc->lock);
250	}
251	irq_unlock_sparse();
252
253	return 0;
254}
255