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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> | |
48 | #include <linux/gfp.h> | |
49 | #include <linux/mutex.h> | |
50 | #include <linux/cpu.h> | |
51 | #include <xen/events.h> | |
52 | #include <xen/evtchn.h> | |
53 | #include <asm/xen/hypervisor.h> | |
54 | ||
55 | struct per_user_data { | |
0a4666b5 JF |
56 | struct mutex bind_mutex; /* serialize bind/unbind operations */ |
57 | ||
f7116284 IC |
58 | /* Notification ring, accessed via /dev/xen/evtchn. */ |
59 | #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) | |
60 | #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) | |
61 | evtchn_port_t *ring; | |
62 | unsigned int ring_cons, ring_prod, ring_overflow; | |
63 | struct mutex ring_cons_mutex; /* protect against concurrent readers */ | |
64 | ||
65 | /* Processes wait on this queue when ring is empty. */ | |
66 | wait_queue_head_t evtchn_wait; | |
67 | struct fasync_struct *evtchn_async_queue; | |
68 | const char *name; | |
69 | }; | |
70 | ||
71 | /* Who's bound to each port? */ | |
72 | static struct per_user_data *port_user[NR_EVENT_CHANNELS]; | |
0a4666b5 | 73 | static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ |
f7116284 IC |
74 | |
75 | irqreturn_t evtchn_interrupt(int irq, void *data) | |
76 | { | |
77 | unsigned int port = (unsigned long)data; | |
78 | struct per_user_data *u; | |
79 | ||
80 | spin_lock(&port_user_lock); | |
81 | ||
82 | u = port_user[port]; | |
83 | ||
84 | disable_irq_nosync(irq); | |
85 | ||
86 | if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { | |
87 | u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port; | |
88 | wmb(); /* Ensure ring contents visible */ | |
89 | if (u->ring_cons == u->ring_prod++) { | |
90 | wake_up_interruptible(&u->evtchn_wait); | |
91 | kill_fasync(&u->evtchn_async_queue, | |
92 | SIGIO, POLL_IN); | |
93 | } | |
94 | } else { | |
95 | u->ring_overflow = 1; | |
96 | } | |
97 | ||
98 | spin_unlock(&port_user_lock); | |
99 | ||
100 | return IRQ_HANDLED; | |
101 | } | |
102 | ||
103 | static ssize_t evtchn_read(struct file *file, char __user *buf, | |
104 | size_t count, loff_t *ppos) | |
105 | { | |
106 | int rc; | |
107 | unsigned int c, p, bytes1 = 0, bytes2 = 0; | |
108 | struct per_user_data *u = file->private_data; | |
109 | ||
110 | /* Whole number of ports. */ | |
111 | count &= ~(sizeof(evtchn_port_t)-1); | |
112 | ||
113 | if (count == 0) | |
114 | return 0; | |
115 | ||
116 | if (count > PAGE_SIZE) | |
117 | count = PAGE_SIZE; | |
118 | ||
119 | for (;;) { | |
120 | mutex_lock(&u->ring_cons_mutex); | |
121 | ||
122 | rc = -EFBIG; | |
123 | if (u->ring_overflow) | |
124 | goto unlock_out; | |
125 | ||
126 | c = u->ring_cons; | |
127 | p = u->ring_prod; | |
128 | if (c != p) | |
129 | break; | |
130 | ||
131 | mutex_unlock(&u->ring_cons_mutex); | |
132 | ||
133 | if (file->f_flags & O_NONBLOCK) | |
134 | return -EAGAIN; | |
135 | ||
136 | rc = wait_event_interruptible(u->evtchn_wait, | |
137 | u->ring_cons != u->ring_prod); | |
138 | if (rc) | |
139 | return rc; | |
140 | } | |
141 | ||
142 | /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ | |
143 | if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { | |
144 | bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * | |
145 | sizeof(evtchn_port_t); | |
146 | bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); | |
147 | } else { | |
148 | bytes1 = (p - c) * sizeof(evtchn_port_t); | |
149 | bytes2 = 0; | |
150 | } | |
151 | ||
152 | /* Truncate chunks according to caller's maximum byte count. */ | |
153 | if (bytes1 > count) { | |
154 | bytes1 = count; | |
155 | bytes2 = 0; | |
156 | } else if ((bytes1 + bytes2) > count) { | |
157 | bytes2 = count - bytes1; | |
158 | } | |
159 | ||
160 | rc = -EFAULT; | |
161 | rmb(); /* Ensure that we see the port before we copy it. */ | |
162 | if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || | |
163 | ((bytes2 != 0) && | |
164 | copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) | |
165 | goto unlock_out; | |
166 | ||
167 | u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t); | |
168 | rc = bytes1 + bytes2; | |
169 | ||
170 | unlock_out: | |
171 | mutex_unlock(&u->ring_cons_mutex); | |
172 | return rc; | |
173 | } | |
174 | ||
175 | static ssize_t evtchn_write(struct file *file, const char __user *buf, | |
176 | size_t count, loff_t *ppos) | |
177 | { | |
178 | int rc, i; | |
179 | evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
180 | struct per_user_data *u = file->private_data; | |
181 | ||
182 | if (kbuf == NULL) | |
183 | return -ENOMEM; | |
184 | ||
185 | /* Whole number of ports. */ | |
186 | count &= ~(sizeof(evtchn_port_t)-1); | |
187 | ||
188 | rc = 0; | |
189 | if (count == 0) | |
190 | goto out; | |
191 | ||
192 | if (count > PAGE_SIZE) | |
193 | count = PAGE_SIZE; | |
194 | ||
195 | rc = -EFAULT; | |
196 | if (copy_from_user(kbuf, buf, count) != 0) | |
197 | goto out; | |
198 | ||
199 | spin_lock_irq(&port_user_lock); | |
200 | for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) | |
201 | if ((kbuf[i] < NR_EVENT_CHANNELS) && (port_user[kbuf[i]] == u)) | |
202 | enable_irq(irq_from_evtchn(kbuf[i])); | |
203 | spin_unlock_irq(&port_user_lock); | |
204 | ||
205 | rc = count; | |
206 | ||
207 | out: | |
208 | free_page((unsigned long)kbuf); | |
209 | return rc; | |
210 | } | |
211 | ||
212 | static int evtchn_bind_to_user(struct per_user_data *u, int port) | |
213 | { | |
f7116284 IC |
214 | int rc = 0; |
215 | ||
0a4666b5 JF |
216 | /* |
217 | * Ports are never reused, so every caller should pass in a | |
218 | * unique port. | |
219 | * | |
220 | * (Locking not necessary because we haven't registered the | |
221 | * interrupt handler yet, and our caller has already | |
222 | * serialized bind operations.) | |
223 | */ | |
f7116284 | 224 | BUG_ON(port_user[port] != NULL); |
f7116284 IC |
225 | port_user[port] = u; |
226 | ||
0a4666b5 JF |
227 | rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, |
228 | u->name, (void *)(unsigned long)port); | |
229 | if (rc >= 0) | |
230 | rc = 0; | |
231 | ||
f7116284 IC |
232 | return rc; |
233 | } | |
234 | ||
235 | static void evtchn_unbind_from_user(struct per_user_data *u, int port) | |
236 | { | |
237 | int irq = irq_from_evtchn(port); | |
238 | ||
239 | unbind_from_irqhandler(irq, (void *)(unsigned long)port); | |
0a4666b5 JF |
240 | |
241 | /* make sure we unbind the irq handler before clearing the port */ | |
242 | barrier(); | |
243 | ||
f7116284 IC |
244 | port_user[port] = NULL; |
245 | } | |
246 | ||
247 | static long evtchn_ioctl(struct file *file, | |
248 | unsigned int cmd, unsigned long arg) | |
249 | { | |
250 | int rc; | |
251 | struct per_user_data *u = file->private_data; | |
252 | void __user *uarg = (void __user *) arg; | |
253 | ||
0a4666b5 JF |
254 | /* Prevent bind from racing with unbind */ |
255 | mutex_lock(&u->bind_mutex); | |
256 | ||
f7116284 IC |
257 | switch (cmd) { |
258 | case IOCTL_EVTCHN_BIND_VIRQ: { | |
259 | struct ioctl_evtchn_bind_virq bind; | |
260 | struct evtchn_bind_virq bind_virq; | |
261 | ||
262 | rc = -EFAULT; | |
263 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
264 | break; | |
265 | ||
266 | bind_virq.virq = bind.virq; | |
267 | bind_virq.vcpu = 0; | |
268 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, | |
269 | &bind_virq); | |
270 | if (rc != 0) | |
271 | break; | |
272 | ||
273 | rc = evtchn_bind_to_user(u, bind_virq.port); | |
274 | if (rc == 0) | |
275 | rc = bind_virq.port; | |
276 | break; | |
277 | } | |
278 | ||
279 | case IOCTL_EVTCHN_BIND_INTERDOMAIN: { | |
280 | struct ioctl_evtchn_bind_interdomain bind; | |
281 | struct evtchn_bind_interdomain bind_interdomain; | |
282 | ||
283 | rc = -EFAULT; | |
284 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
285 | break; | |
286 | ||
287 | bind_interdomain.remote_dom = bind.remote_domain; | |
288 | bind_interdomain.remote_port = bind.remote_port; | |
289 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, | |
290 | &bind_interdomain); | |
291 | if (rc != 0) | |
292 | break; | |
293 | ||
294 | rc = evtchn_bind_to_user(u, bind_interdomain.local_port); | |
295 | if (rc == 0) | |
296 | rc = bind_interdomain.local_port; | |
297 | break; | |
298 | } | |
299 | ||
300 | case IOCTL_EVTCHN_BIND_UNBOUND_PORT: { | |
301 | struct ioctl_evtchn_bind_unbound_port bind; | |
302 | struct evtchn_alloc_unbound alloc_unbound; | |
303 | ||
304 | rc = -EFAULT; | |
305 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
306 | break; | |
307 | ||
308 | alloc_unbound.dom = DOMID_SELF; | |
309 | alloc_unbound.remote_dom = bind.remote_domain; | |
310 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, | |
311 | &alloc_unbound); | |
312 | if (rc != 0) | |
313 | break; | |
314 | ||
315 | rc = evtchn_bind_to_user(u, alloc_unbound.port); | |
316 | if (rc == 0) | |
317 | rc = alloc_unbound.port; | |
318 | break; | |
319 | } | |
320 | ||
321 | case IOCTL_EVTCHN_UNBIND: { | |
322 | struct ioctl_evtchn_unbind unbind; | |
323 | ||
324 | rc = -EFAULT; | |
325 | if (copy_from_user(&unbind, uarg, sizeof(unbind))) | |
326 | break; | |
327 | ||
328 | rc = -EINVAL; | |
329 | if (unbind.port >= NR_EVENT_CHANNELS) | |
330 | break; | |
331 | ||
332 | spin_lock_irq(&port_user_lock); | |
333 | ||
334 | rc = -ENOTCONN; | |
335 | if (port_user[unbind.port] != u) { | |
336 | spin_unlock_irq(&port_user_lock); | |
337 | break; | |
338 | } | |
339 | ||
340 | evtchn_unbind_from_user(u, unbind.port); | |
341 | ||
342 | spin_unlock_irq(&port_user_lock); | |
343 | ||
344 | rc = 0; | |
345 | break; | |
346 | } | |
347 | ||
348 | case IOCTL_EVTCHN_NOTIFY: { | |
349 | struct ioctl_evtchn_notify notify; | |
350 | ||
351 | rc = -EFAULT; | |
352 | if (copy_from_user(¬ify, uarg, sizeof(notify))) | |
353 | break; | |
354 | ||
355 | if (notify.port >= NR_EVENT_CHANNELS) { | |
356 | rc = -EINVAL; | |
357 | } else if (port_user[notify.port] != u) { | |
358 | rc = -ENOTCONN; | |
359 | } else { | |
360 | notify_remote_via_evtchn(notify.port); | |
361 | rc = 0; | |
362 | } | |
363 | break; | |
364 | } | |
365 | ||
366 | case IOCTL_EVTCHN_RESET: { | |
367 | /* Initialise the ring to empty. Clear errors. */ | |
368 | mutex_lock(&u->ring_cons_mutex); | |
369 | spin_lock_irq(&port_user_lock); | |
370 | u->ring_cons = u->ring_prod = u->ring_overflow = 0; | |
371 | spin_unlock_irq(&port_user_lock); | |
372 | mutex_unlock(&u->ring_cons_mutex); | |
373 | rc = 0; | |
374 | break; | |
375 | } | |
376 | ||
377 | default: | |
378 | rc = -ENOSYS; | |
379 | break; | |
380 | } | |
0a4666b5 | 381 | mutex_unlock(&u->bind_mutex); |
f7116284 IC |
382 | |
383 | return rc; | |
384 | } | |
385 | ||
386 | static unsigned int evtchn_poll(struct file *file, poll_table *wait) | |
387 | { | |
388 | unsigned int mask = POLLOUT | POLLWRNORM; | |
389 | struct per_user_data *u = file->private_data; | |
390 | ||
391 | poll_wait(file, &u->evtchn_wait, wait); | |
392 | if (u->ring_cons != u->ring_prod) | |
393 | mask |= POLLIN | POLLRDNORM; | |
394 | if (u->ring_overflow) | |
395 | mask = POLLERR; | |
396 | return mask; | |
397 | } | |
398 | ||
399 | static int evtchn_fasync(int fd, struct file *filp, int on) | |
400 | { | |
401 | struct per_user_data *u = filp->private_data; | |
402 | return fasync_helper(fd, filp, on, &u->evtchn_async_queue); | |
403 | } | |
404 | ||
405 | static int evtchn_open(struct inode *inode, struct file *filp) | |
406 | { | |
407 | struct per_user_data *u; | |
408 | ||
409 | u = kzalloc(sizeof(*u), GFP_KERNEL); | |
410 | if (u == NULL) | |
411 | return -ENOMEM; | |
412 | ||
413 | u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm); | |
414 | if (u->name == NULL) { | |
415 | kfree(u); | |
416 | return -ENOMEM; | |
417 | } | |
418 | ||
419 | init_waitqueue_head(&u->evtchn_wait); | |
420 | ||
421 | u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
422 | if (u->ring == NULL) { | |
423 | kfree(u->name); | |
424 | kfree(u); | |
425 | return -ENOMEM; | |
426 | } | |
427 | ||
0a4666b5 | 428 | mutex_init(&u->bind_mutex); |
f7116284 IC |
429 | mutex_init(&u->ring_cons_mutex); |
430 | ||
431 | filp->private_data = u; | |
432 | ||
433 | return 0; | |
434 | } | |
435 | ||
436 | static int evtchn_release(struct inode *inode, struct file *filp) | |
437 | { | |
438 | int i; | |
439 | struct per_user_data *u = filp->private_data; | |
440 | ||
441 | spin_lock_irq(&port_user_lock); | |
442 | ||
443 | free_page((unsigned long)u->ring); | |
444 | ||
445 | for (i = 0; i < NR_EVENT_CHANNELS; i++) { | |
446 | if (port_user[i] != u) | |
447 | continue; | |
448 | ||
449 | evtchn_unbind_from_user(port_user[i], i); | |
450 | } | |
451 | ||
452 | spin_unlock_irq(&port_user_lock); | |
453 | ||
454 | kfree(u->name); | |
455 | kfree(u); | |
456 | ||
457 | return 0; | |
458 | } | |
459 | ||
460 | static const struct file_operations evtchn_fops = { | |
461 | .owner = THIS_MODULE, | |
462 | .read = evtchn_read, | |
463 | .write = evtchn_write, | |
464 | .unlocked_ioctl = evtchn_ioctl, | |
465 | .poll = evtchn_poll, | |
466 | .fasync = evtchn_fasync, | |
467 | .open = evtchn_open, | |
468 | .release = evtchn_release, | |
469 | }; | |
470 | ||
471 | static struct miscdevice evtchn_miscdev = { | |
472 | .minor = MISC_DYNAMIC_MINOR, | |
473 | .name = "evtchn", | |
474 | .fops = &evtchn_fops, | |
475 | }; | |
476 | static int __init evtchn_init(void) | |
477 | { | |
478 | int err; | |
479 | ||
480 | if (!xen_domain()) | |
481 | return -ENODEV; | |
482 | ||
483 | spin_lock_init(&port_user_lock); | |
484 | memset(port_user, 0, sizeof(port_user)); | |
485 | ||
486 | /* Create '/dev/misc/evtchn'. */ | |
487 | err = misc_register(&evtchn_miscdev); | |
488 | if (err != 0) { | |
489 | printk(KERN_ALERT "Could not register /dev/misc/evtchn\n"); | |
490 | return err; | |
491 | } | |
492 | ||
493 | printk(KERN_INFO "Event-channel device installed.\n"); | |
494 | ||
495 | return 0; | |
496 | } | |
497 | ||
498 | static void __exit evtchn_cleanup(void) | |
499 | { | |
500 | misc_deregister(&evtchn_miscdev); | |
501 | } | |
502 | ||
503 | module_init(evtchn_init); | |
504 | module_exit(evtchn_cleanup); | |
505 | ||
506 | MODULE_LICENSE("GPL"); |