summaryrefslogtreecommitdiffstats
path: root/kernel/irq/ipi.c
blob: 961d4af76af37708ee842bfb7a040c9bd31f504b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015 Imagination Technologies Ltd
 * Author: Qais Yousef <qais.yousef@imgtec.com>
 *
 * This file contains driver APIs to the IPI subsystem.
 */

#define pr_fmt(fmt) "genirq/ipi: " fmt

#include <linux/irqdomain.h>
#include <linux/irq.h>

/**
 * irq_reserve_ipi() - Setup an IPI to destination cpumask
 * @domain:	IPI domain
 * @dest:	cpumask of CPUs which can receive the IPI
 *
 * Allocate a virq that can be used to send IPI to any CPU in dest mask.
 *
 * Return: Linux IRQ number on success or error code on failure
 */
int irq_reserve_ipi(struct irq_domain *domain,
			     const struct cpumask *dest)
{
	unsigned int nr_irqs, offset;
	struct irq_data *data;
	int virq, i;

	if (!domain ||!irq_domain_is_ipi(domain)) {
		pr_warn("Reservation on a non IPI domain\n");
		return -EINVAL;
	}

	if (!cpumask_subset(dest, cpu_possible_mask)) {
		pr_warn("Reservation is not in possible_cpu_mask\n");
		return -EINVAL;
	}

	nr_irqs = cpumask_weight(dest);
	if (!nr_irqs) {
		pr_warn("Reservation for empty destination mask\n");
		return -EINVAL;
	}

	if (irq_domain_is_ipi_single(domain)) {
		/*
		 * If the underlying implementation uses a single HW irq on
		 * all cpus then we only need a single Linux irq number for
		 * it. We have no restrictions vs. the destination mask. The
		 * underlying implementation can deal with holes nicely.
		 */
		nr_irqs = 1;
		offset = 0;
	} else {
		unsigned int next;

		/*
		 * The IPI requires a separate HW irq on each CPU. We require
		 * that the destination mask is consecutive. If an
		 * implementation needs to support holes, it can reserve
		 * several IPI ranges.
		 */
		offset = cpumask_first(dest);
		/*
		 * Find a hole and if found look for another set bit after the
		 * hole. For now we don't support this scenario.
		 */
		next = cpumask_next_zero(offset, dest);
		if (next < nr_cpu_ids)
			next = cpumask_next(next, dest);
		if (next < nr_cpu_ids) {
			pr_warn("Destination mask has holes\n");
			return -EINVAL;
		}
	}

	virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE, NULL);
	if (virq <= 0) {
		pr_warn("Can't reserve IPI, failed to alloc descs\n");
		return -ENOMEM;
	}

	virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
				       (void *) dest, true, NULL);

	if (virq <= 0) {
		pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
		goto free_descs;
	}

	for (i = 0; i < nr_irqs; i++) {
		data = irq_get_irq_data(virq + i);
		cpumask_copy(data->common->affinity, dest);
		data->common->ipi_offset = offset;
		irq_set_status_flags(virq + i, IRQ_NO_BALANCING);
	}
	return virq;

free_descs:
	irq_free_descs(virq, nr_irqs);
	return -EBUSY;
}

/**
 * irq_destroy_ipi() - unreserve an IPI that was previously allocated
 * @irq:	Linux IRQ number to be destroyed
 * @dest:	cpumask of CPUs which should have the IPI removed
 *
 * The IPIs allocated with irq_reserve_ipi() are returned to the system
 * destroying all virqs associated with them.
 *
 * Return: %0 on success or error code on failure.
 */
int irq_destroy_ipi(unsigned int irq, const struct cpumask *dest)
{
	struct irq_data *data = irq_get_irq_data(irq);
	const struct cpumask *ipimask;
	struct irq_domain *domain;
	unsigned int nr_irqs;

	if (!irq || !data)
		return -EINVAL;

	domain = data->domain;
	if (WARN_ON(domain == NULL))
		return -EINVAL;

	if (!irq_domain_is_ipi(domain)) {
		pr_warn("Trying to destroy a non IPI domain!\n");
		return -EINVAL;
	}

	ipimask = irq_data_get_affinity_mask(data);
	if (!ipimask || WARN_ON(!cpumask_subset(dest, ipimask)))
		/*
		 * Must be destroying a subset of CPUs to which this IPI
		 * was set up to target
		 */
		return -EINVAL;

	if (irq_domain_is_ipi_per_cpu(domain)) {
		irq = irq + cpumask_first(dest) - data->common->ipi_offset;
		nr_irqs = cpumask_weight(dest);
	} else {
		nr_irqs = 1;
	}

	irq_domain_free_irqs(irq, nr_irqs);
	return 0;
}

/**
 * ipi_get_hwirq - Get the hwirq associated with an IPI to a CPU
 * @irq:	Linux IRQ number
 * @cpu:	the target CPU
 *
 * When dealing with coprocessors IPI, we need to inform the coprocessor of
 * the hwirq it needs to use to receive and send IPIs.
 *
 * Return: hwirq value on success or INVALID_HWIRQ on failure.
 */
irq_hw_number_t ipi_get_hwirq(unsigned int irq, unsigned int cpu)
{
	struct irq_data *data = irq_get_irq_data(irq);
	const struct cpumask *ipimask;

	if (!data || cpu >= nr_cpu_ids)
		return INVALID_HWIRQ;

	ipimask = irq_data_get_affinity_mask(data);
	if (!ipimask || !cpumask_test_cpu(cpu, ipimask))
		return INVALID_HWIRQ;

	/*
	 * Get the real hardware irq number if the underlying implementation
	 * uses a separate irq per cpu. If the underlying implementation uses
	 * a single hardware irq for all cpus then the IPI send mechanism
	 * needs to take care of the cpu destinations.
	 */
	if (irq_domain_is_ipi_per_cpu(data->domain))
		data = irq_get_irq_data(irq + cpu - data->common->ipi_offset);

	return data ? irqd_to_hwirq(data) : INVALID_HWIRQ;
}
EXPORT_SYMBOL_GPL(ipi_get_hwirq);

static int ipi_send_verify(struct irq_chip *chip, struct irq_data *data,
			   const struct cpumask *dest, unsigned int cpu)
{
	const struct cpumask *ipimask;

	if (!chip || !data)
		return -EINVAL;

	if (!chip->ipi_send_single && !chip->ipi_send_mask)
		return -EINVAL;

	if (cpu >= nr_cpu_ids)
		return -EINVAL;

	ipimask = irq_data_get_affinity_mask(data);
	if (!ipimask)
		return -EINVAL;

	if (dest) {
		if (!cpumask_subset(dest, ipimask))
			return -EINVAL;
	} else {
		if (!cpumask_test_cpu(cpu, ipimask))
			return -EINVAL;
	}
	return 0;
}

/**
 * __ipi_send_single - send an IPI to a target Linux SMP CPU
 * @desc:	pointer to irq_desc of the IRQ
 * @cpu:	destination CPU, must in the destination mask passed to
 *		irq_reserve_ipi()
 *
 * This function is for architecture or core code to speed up IPI sending. Not
 * usable from driver code.
 *
 * Return: %0 on success or negative error number on failure.
 */
int __ipi_send_single(struct irq_desc *desc, unsigned int cpu)
{
	struct irq_data *data = irq_desc_get_irq_data(desc);
	struct irq_chip *chip = irq_data_get_irq_chip(data);

#ifdef DEBUG
	/*
	 * Minimise the overhead by omitting the checks for Linux SMP IPIs.
	 * Since the callers should be arch or core code which is generally
	 * trusted, only check for errors when debugging.
	 */
	if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
		return -EINVAL;
#endif
	if (!chip->ipi_send_single) {
		chip->ipi_send_mask(data, cpumask_of(cpu));
		return 0;
	}

	/* FIXME: Store this information in irqdata flags */
	if (irq_domain_is_ipi_per_cpu(data->domain) &&
	    cpu != data->common->ipi_offset) {
		/* use the correct data for that cpu */
		unsigned irq = data->irq + cpu - data->common->ipi_offset;

		data = irq_get_irq_data(irq);
	}
	chip->ipi_send_single(data, cpu);
	return 0;
}

/**
 * __ipi_send_mask - send an IPI to target Linux SMP CPU(s)
 * @desc:	pointer to irq_desc of the IRQ
 * @dest:	dest CPU(s), must be a subset of the mask passed to
 *		irq_reserve_ipi()
 *
 * This function is for architecture or core code to speed up IPI sending. Not
 * usable from driver code.
 *
 * Return: %0 on success or negative error number on failure.
 */
int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest)
{
	struct irq_data *data = irq_desc_get_irq_data(desc);
	struct irq_chip *chip = irq_data_get_irq_chip(data);
	unsigned int cpu;

#ifdef DEBUG
	/*
	 * Minimise the overhead by omitting the checks for Linux SMP IPIs.
	 * Since the callers should be arch or core code which is generally
	 * trusted, only check for errors when debugging.
	 */
	if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
		return -EINVAL;
#endif
	if (chip->ipi_send_mask) {
		chip->ipi_send_mask(data, dest);
		return 0;
	}

	if (irq_domain_is_ipi_per_cpu(data->domain)) {
		unsigned int base = data->irq;

		for_each_cpu(cpu, dest) {
			unsigned irq = base + cpu - data->common->ipi_offset;

			data = irq_get_irq_data(irq);
			chip->ipi_send_single(data, cpu);
		}
	} else {
		for_each_cpu(cpu, dest)
			chip->ipi_send_single(data, cpu);
	}
	return 0;
}

/**
 * ipi_send_single - Send an IPI to a single CPU
 * @virq:	Linux IRQ number from irq_reserve_ipi()
 * @cpu:	destination CPU, must in the destination mask passed to
 *		irq_reserve_ipi()
 *
 * Return: %0 on success or negative error number on failure.
 */
int ipi_send_single(unsigned int virq, unsigned int cpu)
{
	struct irq_desc *desc = irq_to_desc(virq);
	struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
	struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;

	if (WARN_ON_ONCE(ipi_send_verify(chip, data, NULL, cpu)))
		return -EINVAL;

	return __ipi_send_single(desc, cpu);
}
EXPORT_SYMBOL_GPL(ipi_send_single);

/**
 * ipi_send_mask - Send an IPI to target CPU(s)
 * @virq:	Linux IRQ number from irq_reserve_ipi()
 * @dest:	dest CPU(s), must be a subset of the mask passed to
 *		irq_reserve_ipi()
 *
 * Return: %0 on success or negative error number on failure.
 */
int ipi_send_mask(unsigned int virq, const struct cpumask *dest)
{
	struct irq_desc *desc = irq_to_desc(virq);
	struct irq_data *data = desc ? irq_desc_get_irq_data(desc) : NULL;
	struct irq_chip *chip = data ? irq_data_get_irq_chip(data) : NULL;

	if (WARN_ON_ONCE(ipi_send_verify(chip, data, dest, 0)))
		return -EINVAL;

	return __ipi_send_mask(desc, dest);
}
EXPORT_SYMBOL_GPL(ipi_send_mask);