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f7116284 IC |
1 | /****************************************************************************** |
2 | * evtchn.c | |
3 | * | |
4 | * Driver for receiving and demuxing event-channel signals. | |
5 | * | |
6 | * Copyright (c) 2004-2005, K A Fraser | |
7 | * Multi-process extensions Copyright (c) 2004, Steven Smith | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License version 2 | |
11 | * as published by the Free Software Foundation; or, when distributed | |
12 | * separately from the Linux kernel or incorporated into other | |
13 | * software packages, subject to the following license: | |
14 | * | |
15 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
16 | * of this source file (the "Software"), to deal in the Software without | |
17 | * restriction, including without limitation the rights to use, copy, modify, | |
18 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, | |
19 | * and to permit persons to whom the Software is furnished to do so, subject to | |
20 | * the following conditions: | |
21 | * | |
22 | * The above copyright notice and this permission notice shall be included in | |
23 | * all copies or substantial portions of the Software. | |
24 | * | |
25 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
26 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
27 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
28 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
29 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
30 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
31 | * IN THE SOFTWARE. | |
32 | */ | |
33 | ||
34 | #include <linux/module.h> | |
35 | #include <linux/kernel.h> | |
36 | #include <linux/sched.h> | |
37 | #include <linux/slab.h> | |
38 | #include <linux/string.h> | |
39 | #include <linux/errno.h> | |
40 | #include <linux/fs.h> | |
f7116284 IC |
41 | #include <linux/miscdevice.h> |
42 | #include <linux/major.h> | |
43 | #include <linux/proc_fs.h> | |
44 | #include <linux/stat.h> | |
45 | #include <linux/poll.h> | |
46 | #include <linux/irq.h> | |
47 | #include <linux/init.h> | |
f7116284 IC |
48 | #include <linux/mutex.h> |
49 | #include <linux/cpu.h> | |
1ccbf534 JF |
50 | |
51 | #include <xen/xen.h> | |
f7116284 IC |
52 | #include <xen/events.h> |
53 | #include <xen/evtchn.h> | |
54 | #include <asm/xen/hypervisor.h> | |
55 | ||
56 | struct per_user_data { | |
0a4666b5 JF |
57 | struct mutex bind_mutex; /* serialize bind/unbind operations */ |
58 | ||
f7116284 IC |
59 | /* Notification ring, accessed via /dev/xen/evtchn. */ |
60 | #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) | |
61 | #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) | |
62 | evtchn_port_t *ring; | |
63 | unsigned int ring_cons, ring_prod, ring_overflow; | |
64 | struct mutex ring_cons_mutex; /* protect against concurrent readers */ | |
65 | ||
66 | /* Processes wait on this queue when ring is empty. */ | |
67 | wait_queue_head_t evtchn_wait; | |
68 | struct fasync_struct *evtchn_async_queue; | |
69 | const char *name; | |
70 | }; | |
71 | ||
72 | /* Who's bound to each port? */ | |
73 | static struct per_user_data *port_user[NR_EVENT_CHANNELS]; | |
0a4666b5 | 74 | static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ |
f7116284 IC |
75 | |
76 | irqreturn_t evtchn_interrupt(int irq, void *data) | |
77 | { | |
78 | unsigned int port = (unsigned long)data; | |
79 | struct per_user_data *u; | |
80 | ||
81 | spin_lock(&port_user_lock); | |
82 | ||
83 | u = port_user[port]; | |
84 | ||
85 | disable_irq_nosync(irq); | |
86 | ||
87 | if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { | |
88 | u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port; | |
89 | wmb(); /* Ensure ring contents visible */ | |
90 | if (u->ring_cons == u->ring_prod++) { | |
91 | wake_up_interruptible(&u->evtchn_wait); | |
92 | kill_fasync(&u->evtchn_async_queue, | |
93 | SIGIO, POLL_IN); | |
94 | } | |
95 | } else { | |
96 | u->ring_overflow = 1; | |
97 | } | |
98 | ||
99 | spin_unlock(&port_user_lock); | |
100 | ||
101 | return IRQ_HANDLED; | |
102 | } | |
103 | ||
104 | static ssize_t evtchn_read(struct file *file, char __user *buf, | |
105 | size_t count, loff_t *ppos) | |
106 | { | |
107 | int rc; | |
108 | unsigned int c, p, bytes1 = 0, bytes2 = 0; | |
109 | struct per_user_data *u = file->private_data; | |
110 | ||
111 | /* Whole number of ports. */ | |
112 | count &= ~(sizeof(evtchn_port_t)-1); | |
113 | ||
114 | if (count == 0) | |
115 | return 0; | |
116 | ||
117 | if (count > PAGE_SIZE) | |
118 | count = PAGE_SIZE; | |
119 | ||
120 | for (;;) { | |
121 | mutex_lock(&u->ring_cons_mutex); | |
122 | ||
123 | rc = -EFBIG; | |
124 | if (u->ring_overflow) | |
125 | goto unlock_out; | |
126 | ||
127 | c = u->ring_cons; | |
128 | p = u->ring_prod; | |
129 | if (c != p) | |
130 | break; | |
131 | ||
132 | mutex_unlock(&u->ring_cons_mutex); | |
133 | ||
134 | if (file->f_flags & O_NONBLOCK) | |
135 | return -EAGAIN; | |
136 | ||
137 | rc = wait_event_interruptible(u->evtchn_wait, | |
138 | u->ring_cons != u->ring_prod); | |
139 | if (rc) | |
140 | return rc; | |
141 | } | |
142 | ||
143 | /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ | |
144 | if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { | |
145 | bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * | |
146 | sizeof(evtchn_port_t); | |
147 | bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); | |
148 | } else { | |
149 | bytes1 = (p - c) * sizeof(evtchn_port_t); | |
150 | bytes2 = 0; | |
151 | } | |
152 | ||
153 | /* Truncate chunks according to caller's maximum byte count. */ | |
154 | if (bytes1 > count) { | |
155 | bytes1 = count; | |
156 | bytes2 = 0; | |
157 | } else if ((bytes1 + bytes2) > count) { | |
158 | bytes2 = count - bytes1; | |
159 | } | |
160 | ||
161 | rc = -EFAULT; | |
162 | rmb(); /* Ensure that we see the port before we copy it. */ | |
163 | if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || | |
164 | ((bytes2 != 0) && | |
165 | copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) | |
166 | goto unlock_out; | |
167 | ||
168 | u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t); | |
169 | rc = bytes1 + bytes2; | |
170 | ||
171 | unlock_out: | |
172 | mutex_unlock(&u->ring_cons_mutex); | |
173 | return rc; | |
174 | } | |
175 | ||
176 | static ssize_t evtchn_write(struct file *file, const char __user *buf, | |
177 | size_t count, loff_t *ppos) | |
178 | { | |
179 | int rc, i; | |
180 | evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
181 | struct per_user_data *u = file->private_data; | |
182 | ||
183 | if (kbuf == NULL) | |
184 | return -ENOMEM; | |
185 | ||
186 | /* Whole number of ports. */ | |
187 | count &= ~(sizeof(evtchn_port_t)-1); | |
188 | ||
189 | rc = 0; | |
190 | if (count == 0) | |
191 | goto out; | |
192 | ||
193 | if (count > PAGE_SIZE) | |
194 | count = PAGE_SIZE; | |
195 | ||
196 | rc = -EFAULT; | |
197 | if (copy_from_user(kbuf, buf, count) != 0) | |
198 | goto out; | |
199 | ||
200 | spin_lock_irq(&port_user_lock); | |
201 | for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) | |
202 | if ((kbuf[i] < NR_EVENT_CHANNELS) && (port_user[kbuf[i]] == u)) | |
203 | enable_irq(irq_from_evtchn(kbuf[i])); | |
204 | spin_unlock_irq(&port_user_lock); | |
205 | ||
206 | rc = count; | |
207 | ||
208 | out: | |
209 | free_page((unsigned long)kbuf); | |
210 | return rc; | |
211 | } | |
212 | ||
213 | static int evtchn_bind_to_user(struct per_user_data *u, int port) | |
214 | { | |
f7116284 IC |
215 | int rc = 0; |
216 | ||
0a4666b5 JF |
217 | /* |
218 | * Ports are never reused, so every caller should pass in a | |
219 | * unique port. | |
220 | * | |
221 | * (Locking not necessary because we haven't registered the | |
222 | * interrupt handler yet, and our caller has already | |
223 | * serialized bind operations.) | |
224 | */ | |
f7116284 | 225 | BUG_ON(port_user[port] != NULL); |
f7116284 IC |
226 | port_user[port] = u; |
227 | ||
0a4666b5 JF |
228 | rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, |
229 | u->name, (void *)(unsigned long)port); | |
230 | if (rc >= 0) | |
231 | rc = 0; | |
232 | ||
f7116284 IC |
233 | return rc; |
234 | } | |
235 | ||
236 | static void evtchn_unbind_from_user(struct per_user_data *u, int port) | |
237 | { | |
238 | int irq = irq_from_evtchn(port); | |
239 | ||
240 | unbind_from_irqhandler(irq, (void *)(unsigned long)port); | |
0a4666b5 JF |
241 | |
242 | /* make sure we unbind the irq handler before clearing the port */ | |
243 | barrier(); | |
244 | ||
f7116284 IC |
245 | port_user[port] = NULL; |
246 | } | |
247 | ||
248 | static long evtchn_ioctl(struct file *file, | |
249 | unsigned int cmd, unsigned long arg) | |
250 | { | |
251 | int rc; | |
252 | struct per_user_data *u = file->private_data; | |
253 | void __user *uarg = (void __user *) arg; | |
254 | ||
0a4666b5 JF |
255 | /* Prevent bind from racing with unbind */ |
256 | mutex_lock(&u->bind_mutex); | |
257 | ||
f7116284 IC |
258 | switch (cmd) { |
259 | case IOCTL_EVTCHN_BIND_VIRQ: { | |
260 | struct ioctl_evtchn_bind_virq bind; | |
261 | struct evtchn_bind_virq bind_virq; | |
262 | ||
263 | rc = -EFAULT; | |
264 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
265 | break; | |
266 | ||
267 | bind_virq.virq = bind.virq; | |
268 | bind_virq.vcpu = 0; | |
269 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, | |
270 | &bind_virq); | |
271 | if (rc != 0) | |
272 | break; | |
273 | ||
274 | rc = evtchn_bind_to_user(u, bind_virq.port); | |
275 | if (rc == 0) | |
276 | rc = bind_virq.port; | |
277 | break; | |
278 | } | |
279 | ||
280 | case IOCTL_EVTCHN_BIND_INTERDOMAIN: { | |
281 | struct ioctl_evtchn_bind_interdomain bind; | |
282 | struct evtchn_bind_interdomain bind_interdomain; | |
283 | ||
284 | rc = -EFAULT; | |
285 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
286 | break; | |
287 | ||
288 | bind_interdomain.remote_dom = bind.remote_domain; | |
289 | bind_interdomain.remote_port = bind.remote_port; | |
290 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, | |
291 | &bind_interdomain); | |
292 | if (rc != 0) | |
293 | break; | |
294 | ||
295 | rc = evtchn_bind_to_user(u, bind_interdomain.local_port); | |
296 | if (rc == 0) | |
297 | rc = bind_interdomain.local_port; | |
298 | break; | |
299 | } | |
300 | ||
301 | case IOCTL_EVTCHN_BIND_UNBOUND_PORT: { | |
302 | struct ioctl_evtchn_bind_unbound_port bind; | |
303 | struct evtchn_alloc_unbound alloc_unbound; | |
304 | ||
305 | rc = -EFAULT; | |
306 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
307 | break; | |
308 | ||
309 | alloc_unbound.dom = DOMID_SELF; | |
310 | alloc_unbound.remote_dom = bind.remote_domain; | |
311 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, | |
312 | &alloc_unbound); | |
313 | if (rc != 0) | |
314 | break; | |
315 | ||
316 | rc = evtchn_bind_to_user(u, alloc_unbound.port); | |
317 | if (rc == 0) | |
318 | rc = alloc_unbound.port; | |
319 | break; | |
320 | } | |
321 | ||
322 | case IOCTL_EVTCHN_UNBIND: { | |
323 | struct ioctl_evtchn_unbind unbind; | |
324 | ||
325 | rc = -EFAULT; | |
326 | if (copy_from_user(&unbind, uarg, sizeof(unbind))) | |
327 | break; | |
328 | ||
329 | rc = -EINVAL; | |
330 | if (unbind.port >= NR_EVENT_CHANNELS) | |
331 | break; | |
332 | ||
333 | spin_lock_irq(&port_user_lock); | |
334 | ||
335 | rc = -ENOTCONN; | |
336 | if (port_user[unbind.port] != u) { | |
337 | spin_unlock_irq(&port_user_lock); | |
338 | break; | |
339 | } | |
340 | ||
341 | evtchn_unbind_from_user(u, unbind.port); | |
342 | ||
343 | spin_unlock_irq(&port_user_lock); | |
344 | ||
345 | rc = 0; | |
346 | break; | |
347 | } | |
348 | ||
349 | case IOCTL_EVTCHN_NOTIFY: { | |
350 | struct ioctl_evtchn_notify notify; | |
351 | ||
352 | rc = -EFAULT; | |
353 | if (copy_from_user(¬ify, uarg, sizeof(notify))) | |
354 | break; | |
355 | ||
356 | if (notify.port >= NR_EVENT_CHANNELS) { | |
357 | rc = -EINVAL; | |
358 | } else if (port_user[notify.port] != u) { | |
359 | rc = -ENOTCONN; | |
360 | } else { | |
361 | notify_remote_via_evtchn(notify.port); | |
362 | rc = 0; | |
363 | } | |
364 | break; | |
365 | } | |
366 | ||
367 | case IOCTL_EVTCHN_RESET: { | |
368 | /* Initialise the ring to empty. Clear errors. */ | |
369 | mutex_lock(&u->ring_cons_mutex); | |
370 | spin_lock_irq(&port_user_lock); | |
371 | u->ring_cons = u->ring_prod = u->ring_overflow = 0; | |
372 | spin_unlock_irq(&port_user_lock); | |
373 | mutex_unlock(&u->ring_cons_mutex); | |
374 | rc = 0; | |
375 | break; | |
376 | } | |
377 | ||
378 | default: | |
379 | rc = -ENOSYS; | |
380 | break; | |
381 | } | |
0a4666b5 | 382 | mutex_unlock(&u->bind_mutex); |
f7116284 IC |
383 | |
384 | return rc; | |
385 | } | |
386 | ||
387 | static unsigned int evtchn_poll(struct file *file, poll_table *wait) | |
388 | { | |
389 | unsigned int mask = POLLOUT | POLLWRNORM; | |
390 | struct per_user_data *u = file->private_data; | |
391 | ||
392 | poll_wait(file, &u->evtchn_wait, wait); | |
393 | if (u->ring_cons != u->ring_prod) | |
394 | mask |= POLLIN | POLLRDNORM; | |
395 | if (u->ring_overflow) | |
396 | mask = POLLERR; | |
397 | return mask; | |
398 | } | |
399 | ||
400 | static int evtchn_fasync(int fd, struct file *filp, int on) | |
401 | { | |
402 | struct per_user_data *u = filp->private_data; | |
403 | return fasync_helper(fd, filp, on, &u->evtchn_async_queue); | |
404 | } | |
405 | ||
406 | static int evtchn_open(struct inode *inode, struct file *filp) | |
407 | { | |
408 | struct per_user_data *u; | |
409 | ||
410 | u = kzalloc(sizeof(*u), GFP_KERNEL); | |
411 | if (u == NULL) | |
412 | return -ENOMEM; | |
413 | ||
414 | u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm); | |
415 | if (u->name == NULL) { | |
416 | kfree(u); | |
417 | return -ENOMEM; | |
418 | } | |
419 | ||
420 | init_waitqueue_head(&u->evtchn_wait); | |
421 | ||
422 | u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
423 | if (u->ring == NULL) { | |
424 | kfree(u->name); | |
425 | kfree(u); | |
426 | return -ENOMEM; | |
427 | } | |
428 | ||
0a4666b5 | 429 | mutex_init(&u->bind_mutex); |
f7116284 IC |
430 | mutex_init(&u->ring_cons_mutex); |
431 | ||
432 | filp->private_data = u; | |
433 | ||
434 | return 0; | |
435 | } | |
436 | ||
437 | static int evtchn_release(struct inode *inode, struct file *filp) | |
438 | { | |
439 | int i; | |
440 | struct per_user_data *u = filp->private_data; | |
441 | ||
442 | spin_lock_irq(&port_user_lock); | |
443 | ||
444 | free_page((unsigned long)u->ring); | |
445 | ||
446 | for (i = 0; i < NR_EVENT_CHANNELS; i++) { | |
447 | if (port_user[i] != u) | |
448 | continue; | |
449 | ||
450 | evtchn_unbind_from_user(port_user[i], i); | |
451 | } | |
452 | ||
453 | spin_unlock_irq(&port_user_lock); | |
454 | ||
455 | kfree(u->name); | |
456 | kfree(u); | |
457 | ||
458 | return 0; | |
459 | } | |
460 | ||
461 | static const struct file_operations evtchn_fops = { | |
462 | .owner = THIS_MODULE, | |
463 | .read = evtchn_read, | |
464 | .write = evtchn_write, | |
465 | .unlocked_ioctl = evtchn_ioctl, | |
466 | .poll = evtchn_poll, | |
467 | .fasync = evtchn_fasync, | |
468 | .open = evtchn_open, | |
469 | .release = evtchn_release, | |
6038f373 | 470 | .llseek = noop_llseek, |
f7116284 IC |
471 | }; |
472 | ||
473 | static struct miscdevice evtchn_miscdev = { | |
474 | .minor = MISC_DYNAMIC_MINOR, | |
475 | .name = "evtchn", | |
476 | .fops = &evtchn_fops, | |
477 | }; | |
478 | static int __init evtchn_init(void) | |
479 | { | |
480 | int err; | |
481 | ||
482 | if (!xen_domain()) | |
483 | return -ENODEV; | |
484 | ||
485 | spin_lock_init(&port_user_lock); | |
486 | memset(port_user, 0, sizeof(port_user)); | |
487 | ||
488 | /* Create '/dev/misc/evtchn'. */ | |
489 | err = misc_register(&evtchn_miscdev); | |
490 | if (err != 0) { | |
491 | printk(KERN_ALERT "Could not register /dev/misc/evtchn\n"); | |
492 | return err; | |
493 | } | |
494 | ||
495 | printk(KERN_INFO "Event-channel device installed.\n"); | |
496 | ||
497 | return 0; | |
498 | } | |
499 | ||
500 | static void __exit evtchn_cleanup(void) | |
501 | { | |
502 | misc_deregister(&evtchn_miscdev); | |
503 | } | |
504 | ||
505 | module_init(evtchn_init); | |
506 | module_exit(evtchn_cleanup); | |
507 | ||
508 | MODULE_LICENSE("GPL"); |