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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f73f8173 AW |
2 | /* |
3 | * IRQ offload/bypass manager | |
4 | * | |
5 | * Copyright (C) 2015 Red Hat, Inc. | |
6 | * Copyright (c) 2015 Linaro Ltd. | |
7 | * | |
f73f8173 AW |
8 | * Various virtualization hardware acceleration techniques allow bypassing or |
9 | * offloading interrupts received from devices around the host kernel. Posted | |
10 | * Interrupts on Intel VT-d systems can allow interrupts to be received | |
11 | * directly by a virtual machine. ARM IRQ Forwarding allows forwarded physical | |
12 | * interrupts to be directly deactivated by the guest. This manager allows | |
13 | * interrupt producers and consumers to find each other to enable this sort of | |
14 | * bypass. | |
15 | */ | |
16 | ||
17 | #include <linux/irqbypass.h> | |
18 | #include <linux/list.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/mutex.h> | |
21 | ||
22 | MODULE_LICENSE("GPL v2"); | |
23 | MODULE_DESCRIPTION("IRQ bypass manager utility module"); | |
24 | ||
25 | static LIST_HEAD(producers); | |
26 | static LIST_HEAD(consumers); | |
27 | static DEFINE_MUTEX(lock); | |
28 | ||
29 | /* @lock must be held when calling connect */ | |
30 | static int __connect(struct irq_bypass_producer *prod, | |
31 | struct irq_bypass_consumer *cons) | |
32 | { | |
33 | int ret = 0; | |
34 | ||
35 | if (prod->stop) | |
36 | prod->stop(prod); | |
37 | if (cons->stop) | |
38 | cons->stop(cons); | |
39 | ||
40 | if (prod->add_consumer) | |
41 | ret = prod->add_consumer(prod, cons); | |
42 | ||
43 | if (!ret) { | |
44 | ret = cons->add_producer(cons, prod); | |
45 | if (ret && prod->del_consumer) | |
46 | prod->del_consumer(prod, cons); | |
47 | } | |
48 | ||
49 | if (cons->start) | |
50 | cons->start(cons); | |
51 | if (prod->start) | |
52 | prod->start(prod); | |
53 | ||
54 | return ret; | |
55 | } | |
56 | ||
57 | /* @lock must be held when calling disconnect */ | |
58 | static void __disconnect(struct irq_bypass_producer *prod, | |
59 | struct irq_bypass_consumer *cons) | |
60 | { | |
61 | if (prod->stop) | |
62 | prod->stop(prod); | |
63 | if (cons->stop) | |
64 | cons->stop(cons); | |
65 | ||
66 | cons->del_producer(cons, prod); | |
67 | ||
68 | if (prod->del_consumer) | |
69 | prod->del_consumer(prod, cons); | |
70 | ||
71 | if (cons->start) | |
72 | cons->start(cons); | |
73 | if (prod->start) | |
74 | prod->start(prod); | |
75 | } | |
76 | ||
77 | /** | |
78 | * irq_bypass_register_producer - register IRQ bypass producer | |
79 | * @producer: pointer to producer structure | |
80 | * | |
81 | * Add the provided IRQ producer to the list of producers and connect | |
82 | * with any matching token found on the IRQ consumers list. | |
83 | */ | |
84 | int irq_bypass_register_producer(struct irq_bypass_producer *producer) | |
85 | { | |
86 | struct irq_bypass_producer *tmp; | |
87 | struct irq_bypass_consumer *consumer; | |
bbfdafa8 | 88 | int ret; |
f73f8173 | 89 | |
b52f3ed0 AW |
90 | if (!producer->token) |
91 | return -EINVAL; | |
92 | ||
f73f8173 AW |
93 | might_sleep(); |
94 | ||
95 | if (!try_module_get(THIS_MODULE)) | |
96 | return -ENODEV; | |
97 | ||
98 | mutex_lock(&lock); | |
99 | ||
100 | list_for_each_entry(tmp, &producers, node) { | |
101 | if (tmp->token == producer->token) { | |
bbfdafa8 ML |
102 | ret = -EBUSY; |
103 | goto out_err; | |
f73f8173 AW |
104 | } |
105 | } | |
106 | ||
107 | list_for_each_entry(consumer, &consumers, node) { | |
108 | if (consumer->token == producer->token) { | |
bbfdafa8 ML |
109 | ret = __connect(producer, consumer); |
110 | if (ret) | |
111 | goto out_err; | |
f73f8173 AW |
112 | break; |
113 | } | |
114 | } | |
115 | ||
116 | list_add(&producer->node, &producers); | |
117 | ||
118 | mutex_unlock(&lock); | |
119 | ||
120 | return 0; | |
bbfdafa8 ML |
121 | out_err: |
122 | mutex_unlock(&lock); | |
123 | module_put(THIS_MODULE); | |
124 | return ret; | |
f73f8173 AW |
125 | } |
126 | EXPORT_SYMBOL_GPL(irq_bypass_register_producer); | |
127 | ||
128 | /** | |
129 | * irq_bypass_unregister_producer - unregister IRQ bypass producer | |
130 | * @producer: pointer to producer structure | |
131 | * | |
132 | * Remove a previously registered IRQ producer from the list of producers | |
133 | * and disconnect it from any connected IRQ consumer. | |
134 | */ | |
135 | void irq_bypass_unregister_producer(struct irq_bypass_producer *producer) | |
136 | { | |
137 | struct irq_bypass_producer *tmp; | |
138 | struct irq_bypass_consumer *consumer; | |
139 | ||
b52f3ed0 AW |
140 | if (!producer->token) |
141 | return; | |
142 | ||
f73f8173 AW |
143 | might_sleep(); |
144 | ||
145 | if (!try_module_get(THIS_MODULE)) | |
146 | return; /* nothing in the list anyway */ | |
147 | ||
148 | mutex_lock(&lock); | |
149 | ||
150 | list_for_each_entry(tmp, &producers, node) { | |
151 | if (tmp->token != producer->token) | |
152 | continue; | |
153 | ||
154 | list_for_each_entry(consumer, &consumers, node) { | |
155 | if (consumer->token == producer->token) { | |
156 | __disconnect(producer, consumer); | |
157 | break; | |
158 | } | |
159 | } | |
160 | ||
161 | list_del(&producer->node); | |
162 | module_put(THIS_MODULE); | |
163 | break; | |
164 | } | |
165 | ||
166 | mutex_unlock(&lock); | |
167 | ||
168 | module_put(THIS_MODULE); | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer); | |
171 | ||
172 | /** | |
173 | * irq_bypass_register_consumer - register IRQ bypass consumer | |
174 | * @consumer: pointer to consumer structure | |
175 | * | |
176 | * Add the provided IRQ consumer to the list of consumers and connect | |
177 | * with any matching token found on the IRQ producer list. | |
178 | */ | |
179 | int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer) | |
180 | { | |
181 | struct irq_bypass_consumer *tmp; | |
182 | struct irq_bypass_producer *producer; | |
8262fe85 | 183 | int ret; |
f73f8173 | 184 | |
b52f3ed0 AW |
185 | if (!consumer->token || |
186 | !consumer->add_producer || !consumer->del_producer) | |
f73f8173 AW |
187 | return -EINVAL; |
188 | ||
189 | might_sleep(); | |
190 | ||
191 | if (!try_module_get(THIS_MODULE)) | |
192 | return -ENODEV; | |
193 | ||
194 | mutex_lock(&lock); | |
195 | ||
196 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 197 | if (tmp->token == consumer->token || tmp == consumer) { |
8262fe85 ML |
198 | ret = -EBUSY; |
199 | goto out_err; | |
f73f8173 AW |
200 | } |
201 | } | |
202 | ||
203 | list_for_each_entry(producer, &producers, node) { | |
204 | if (producer->token == consumer->token) { | |
8262fe85 ML |
205 | ret = __connect(producer, consumer); |
206 | if (ret) | |
207 | goto out_err; | |
f73f8173 AW |
208 | break; |
209 | } | |
210 | } | |
211 | ||
212 | list_add(&consumer->node, &consumers); | |
213 | ||
214 | mutex_unlock(&lock); | |
215 | ||
216 | return 0; | |
8262fe85 ML |
217 | out_err: |
218 | mutex_unlock(&lock); | |
219 | module_put(THIS_MODULE); | |
220 | return ret; | |
f73f8173 AW |
221 | } |
222 | EXPORT_SYMBOL_GPL(irq_bypass_register_consumer); | |
223 | ||
224 | /** | |
225 | * irq_bypass_unregister_consumer - unregister IRQ bypass consumer | |
226 | * @consumer: pointer to consumer structure | |
227 | * | |
228 | * Remove a previously registered IRQ consumer from the list of consumers | |
229 | * and disconnect it from any connected IRQ producer. | |
230 | */ | |
231 | void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer) | |
232 | { | |
233 | struct irq_bypass_consumer *tmp; | |
234 | struct irq_bypass_producer *producer; | |
235 | ||
b52f3ed0 AW |
236 | if (!consumer->token) |
237 | return; | |
238 | ||
f73f8173 AW |
239 | might_sleep(); |
240 | ||
241 | if (!try_module_get(THIS_MODULE)) | |
242 | return; /* nothing in the list anyway */ | |
243 | ||
244 | mutex_lock(&lock); | |
245 | ||
246 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 247 | if (tmp != consumer) |
f73f8173 AW |
248 | continue; |
249 | ||
250 | list_for_each_entry(producer, &producers, node) { | |
251 | if (producer->token == consumer->token) { | |
252 | __disconnect(producer, consumer); | |
253 | break; | |
254 | } | |
255 | } | |
256 | ||
257 | list_del(&consumer->node); | |
258 | module_put(THIS_MODULE); | |
259 | break; | |
260 | } | |
261 | ||
262 | mutex_unlock(&lock); | |
263 | ||
264 | module_put(THIS_MODULE); | |
265 | } | |
266 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer); |