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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 | ||
e3cc067b JF |
72 | /* |
73 | * Who's bound to each port? This is logically an array of struct | |
74 | * per_user_data *, but we encode the current enabled-state in bit 0. | |
75 | */ | |
93afe0b7 | 76 | static unsigned long *port_user; |
0a4666b5 | 77 | static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ |
f7116284 | 78 | |
e3cc067b JF |
79 | static inline struct per_user_data *get_port_user(unsigned port) |
80 | { | |
81 | return (struct per_user_data *)(port_user[port] & ~1); | |
82 | } | |
83 | ||
84 | static inline void set_port_user(unsigned port, struct per_user_data *u) | |
85 | { | |
86 | port_user[port] = (unsigned long)u; | |
87 | } | |
88 | ||
89 | static inline bool get_port_enabled(unsigned port) | |
90 | { | |
91 | return port_user[port] & 1; | |
92 | } | |
93 | ||
94 | static inline void set_port_enabled(unsigned port, bool enabled) | |
95 | { | |
96 | if (enabled) | |
97 | port_user[port] |= 1; | |
98 | else | |
99 | port_user[port] &= ~1; | |
100 | } | |
101 | ||
70697d54 | 102 | static irqreturn_t evtchn_interrupt(int irq, void *data) |
f7116284 IC |
103 | { |
104 | unsigned int port = (unsigned long)data; | |
105 | struct per_user_data *u; | |
106 | ||
107 | spin_lock(&port_user_lock); | |
108 | ||
e3cc067b JF |
109 | u = get_port_user(port); |
110 | ||
0edce91d JF |
111 | WARN(!get_port_enabled(port), |
112 | "Interrupt for port %d, but apparently not enabled; per-user %p\n", | |
113 | port, u); | |
f7116284 IC |
114 | |
115 | disable_irq_nosync(irq); | |
e3cc067b | 116 | set_port_enabled(port, false); |
f7116284 IC |
117 | |
118 | if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { | |
119 | u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port; | |
120 | wmb(); /* Ensure ring contents visible */ | |
121 | if (u->ring_cons == u->ring_prod++) { | |
122 | wake_up_interruptible(&u->evtchn_wait); | |
123 | kill_fasync(&u->evtchn_async_queue, | |
124 | SIGIO, POLL_IN); | |
125 | } | |
e3cc067b | 126 | } else |
f7116284 | 127 | u->ring_overflow = 1; |
f7116284 IC |
128 | |
129 | spin_unlock(&port_user_lock); | |
130 | ||
131 | return IRQ_HANDLED; | |
132 | } | |
133 | ||
134 | static ssize_t evtchn_read(struct file *file, char __user *buf, | |
135 | size_t count, loff_t *ppos) | |
136 | { | |
137 | int rc; | |
138 | unsigned int c, p, bytes1 = 0, bytes2 = 0; | |
139 | struct per_user_data *u = file->private_data; | |
140 | ||
141 | /* Whole number of ports. */ | |
142 | count &= ~(sizeof(evtchn_port_t)-1); | |
143 | ||
144 | if (count == 0) | |
145 | return 0; | |
146 | ||
147 | if (count > PAGE_SIZE) | |
148 | count = PAGE_SIZE; | |
149 | ||
150 | for (;;) { | |
151 | mutex_lock(&u->ring_cons_mutex); | |
152 | ||
153 | rc = -EFBIG; | |
154 | if (u->ring_overflow) | |
155 | goto unlock_out; | |
156 | ||
157 | c = u->ring_cons; | |
158 | p = u->ring_prod; | |
159 | if (c != p) | |
160 | break; | |
161 | ||
162 | mutex_unlock(&u->ring_cons_mutex); | |
163 | ||
164 | if (file->f_flags & O_NONBLOCK) | |
165 | return -EAGAIN; | |
166 | ||
167 | rc = wait_event_interruptible(u->evtchn_wait, | |
168 | u->ring_cons != u->ring_prod); | |
169 | if (rc) | |
170 | return rc; | |
171 | } | |
172 | ||
173 | /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ | |
174 | if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { | |
175 | bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * | |
176 | sizeof(evtchn_port_t); | |
177 | bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); | |
178 | } else { | |
179 | bytes1 = (p - c) * sizeof(evtchn_port_t); | |
180 | bytes2 = 0; | |
181 | } | |
182 | ||
183 | /* Truncate chunks according to caller's maximum byte count. */ | |
184 | if (bytes1 > count) { | |
185 | bytes1 = count; | |
186 | bytes2 = 0; | |
187 | } else if ((bytes1 + bytes2) > count) { | |
188 | bytes2 = count - bytes1; | |
189 | } | |
190 | ||
191 | rc = -EFAULT; | |
192 | rmb(); /* Ensure that we see the port before we copy it. */ | |
193 | if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || | |
194 | ((bytes2 != 0) && | |
195 | copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) | |
196 | goto unlock_out; | |
197 | ||
198 | u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t); | |
199 | rc = bytes1 + bytes2; | |
200 | ||
201 | unlock_out: | |
202 | mutex_unlock(&u->ring_cons_mutex); | |
203 | return rc; | |
204 | } | |
205 | ||
206 | static ssize_t evtchn_write(struct file *file, const char __user *buf, | |
207 | size_t count, loff_t *ppos) | |
208 | { | |
209 | int rc, i; | |
210 | evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
211 | struct per_user_data *u = file->private_data; | |
212 | ||
213 | if (kbuf == NULL) | |
214 | return -ENOMEM; | |
215 | ||
216 | /* Whole number of ports. */ | |
217 | count &= ~(sizeof(evtchn_port_t)-1); | |
218 | ||
219 | rc = 0; | |
220 | if (count == 0) | |
221 | goto out; | |
222 | ||
223 | if (count > PAGE_SIZE) | |
224 | count = PAGE_SIZE; | |
225 | ||
226 | rc = -EFAULT; | |
227 | if (copy_from_user(kbuf, buf, count) != 0) | |
228 | goto out; | |
229 | ||
230 | spin_lock_irq(&port_user_lock); | |
e3cc067b JF |
231 | |
232 | for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) { | |
233 | unsigned port = kbuf[i]; | |
234 | ||
235 | if (port < NR_EVENT_CHANNELS && | |
236 | get_port_user(port) == u && | |
237 | !get_port_enabled(port)) { | |
238 | set_port_enabled(port, true); | |
239 | enable_irq(irq_from_evtchn(port)); | |
240 | } | |
241 | } | |
242 | ||
f7116284 IC |
243 | spin_unlock_irq(&port_user_lock); |
244 | ||
245 | rc = count; | |
246 | ||
247 | out: | |
248 | free_page((unsigned long)kbuf); | |
249 | return rc; | |
250 | } | |
251 | ||
252 | static int evtchn_bind_to_user(struct per_user_data *u, int port) | |
253 | { | |
f7116284 IC |
254 | int rc = 0; |
255 | ||
0a4666b5 JF |
256 | /* |
257 | * Ports are never reused, so every caller should pass in a | |
258 | * unique port. | |
259 | * | |
260 | * (Locking not necessary because we haven't registered the | |
261 | * interrupt handler yet, and our caller has already | |
262 | * serialized bind operations.) | |
263 | */ | |
e3cc067b JF |
264 | BUG_ON(get_port_user(port) != NULL); |
265 | set_port_user(port, u); | |
0edce91d | 266 | set_port_enabled(port, true); /* start enabled */ |
f7116284 | 267 | |
0a4666b5 JF |
268 | rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, |
269 | u->name, (void *)(unsigned long)port); | |
270 | if (rc >= 0) | |
420eb554 | 271 | rc = evtchn_make_refcounted(port); |
0a4666b5 | 272 | |
f7116284 IC |
273 | return rc; |
274 | } | |
275 | ||
276 | static void evtchn_unbind_from_user(struct per_user_data *u, int port) | |
277 | { | |
278 | int irq = irq_from_evtchn(port); | |
279 | ||
280 | unbind_from_irqhandler(irq, (void *)(unsigned long)port); | |
0a4666b5 | 281 | |
e3cc067b | 282 | set_port_user(port, NULL); |
f7116284 IC |
283 | } |
284 | ||
285 | static long evtchn_ioctl(struct file *file, | |
286 | unsigned int cmd, unsigned long arg) | |
287 | { | |
288 | int rc; | |
289 | struct per_user_data *u = file->private_data; | |
290 | void __user *uarg = (void __user *) arg; | |
291 | ||
0a4666b5 JF |
292 | /* Prevent bind from racing with unbind */ |
293 | mutex_lock(&u->bind_mutex); | |
294 | ||
f7116284 IC |
295 | switch (cmd) { |
296 | case IOCTL_EVTCHN_BIND_VIRQ: { | |
297 | struct ioctl_evtchn_bind_virq bind; | |
298 | struct evtchn_bind_virq bind_virq; | |
299 | ||
300 | rc = -EFAULT; | |
301 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
302 | break; | |
303 | ||
304 | bind_virq.virq = bind.virq; | |
305 | bind_virq.vcpu = 0; | |
306 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, | |
307 | &bind_virq); | |
308 | if (rc != 0) | |
309 | break; | |
310 | ||
311 | rc = evtchn_bind_to_user(u, bind_virq.port); | |
312 | if (rc == 0) | |
313 | rc = bind_virq.port; | |
314 | break; | |
315 | } | |
316 | ||
317 | case IOCTL_EVTCHN_BIND_INTERDOMAIN: { | |
318 | struct ioctl_evtchn_bind_interdomain bind; | |
319 | struct evtchn_bind_interdomain bind_interdomain; | |
320 | ||
321 | rc = -EFAULT; | |
322 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
323 | break; | |
324 | ||
325 | bind_interdomain.remote_dom = bind.remote_domain; | |
326 | bind_interdomain.remote_port = bind.remote_port; | |
327 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, | |
328 | &bind_interdomain); | |
329 | if (rc != 0) | |
330 | break; | |
331 | ||
332 | rc = evtchn_bind_to_user(u, bind_interdomain.local_port); | |
333 | if (rc == 0) | |
334 | rc = bind_interdomain.local_port; | |
335 | break; | |
336 | } | |
337 | ||
338 | case IOCTL_EVTCHN_BIND_UNBOUND_PORT: { | |
339 | struct ioctl_evtchn_bind_unbound_port bind; | |
340 | struct evtchn_alloc_unbound alloc_unbound; | |
341 | ||
342 | rc = -EFAULT; | |
343 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
344 | break; | |
345 | ||
346 | alloc_unbound.dom = DOMID_SELF; | |
347 | alloc_unbound.remote_dom = bind.remote_domain; | |
348 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, | |
349 | &alloc_unbound); | |
350 | if (rc != 0) | |
351 | break; | |
352 | ||
353 | rc = evtchn_bind_to_user(u, alloc_unbound.port); | |
354 | if (rc == 0) | |
355 | rc = alloc_unbound.port; | |
356 | break; | |
357 | } | |
358 | ||
359 | case IOCTL_EVTCHN_UNBIND: { | |
360 | struct ioctl_evtchn_unbind unbind; | |
361 | ||
362 | rc = -EFAULT; | |
363 | if (copy_from_user(&unbind, uarg, sizeof(unbind))) | |
364 | break; | |
365 | ||
366 | rc = -EINVAL; | |
367 | if (unbind.port >= NR_EVENT_CHANNELS) | |
368 | break; | |
369 | ||
370 | spin_lock_irq(&port_user_lock); | |
371 | ||
372 | rc = -ENOTCONN; | |
e3cc067b | 373 | if (get_port_user(unbind.port) != u) { |
f7116284 IC |
374 | spin_unlock_irq(&port_user_lock); |
375 | break; | |
376 | } | |
377 | ||
3f5e554f | 378 | disable_irq(irq_from_evtchn(unbind.port)); |
f7116284 IC |
379 | |
380 | spin_unlock_irq(&port_user_lock); | |
381 | ||
3f5e554f JF |
382 | evtchn_unbind_from_user(u, unbind.port); |
383 | ||
f7116284 IC |
384 | rc = 0; |
385 | break; | |
386 | } | |
387 | ||
388 | case IOCTL_EVTCHN_NOTIFY: { | |
389 | struct ioctl_evtchn_notify notify; | |
390 | ||
391 | rc = -EFAULT; | |
392 | if (copy_from_user(¬ify, uarg, sizeof(notify))) | |
393 | break; | |
394 | ||
395 | if (notify.port >= NR_EVENT_CHANNELS) { | |
396 | rc = -EINVAL; | |
e3cc067b | 397 | } else if (get_port_user(notify.port) != u) { |
f7116284 IC |
398 | rc = -ENOTCONN; |
399 | } else { | |
400 | notify_remote_via_evtchn(notify.port); | |
401 | rc = 0; | |
402 | } | |
403 | break; | |
404 | } | |
405 | ||
406 | case IOCTL_EVTCHN_RESET: { | |
407 | /* Initialise the ring to empty. Clear errors. */ | |
408 | mutex_lock(&u->ring_cons_mutex); | |
409 | spin_lock_irq(&port_user_lock); | |
410 | u->ring_cons = u->ring_prod = u->ring_overflow = 0; | |
411 | spin_unlock_irq(&port_user_lock); | |
412 | mutex_unlock(&u->ring_cons_mutex); | |
413 | rc = 0; | |
414 | break; | |
415 | } | |
416 | ||
417 | default: | |
418 | rc = -ENOSYS; | |
419 | break; | |
420 | } | |
0a4666b5 | 421 | mutex_unlock(&u->bind_mutex); |
f7116284 IC |
422 | |
423 | return rc; | |
424 | } | |
425 | ||
426 | static unsigned int evtchn_poll(struct file *file, poll_table *wait) | |
427 | { | |
428 | unsigned int mask = POLLOUT | POLLWRNORM; | |
429 | struct per_user_data *u = file->private_data; | |
430 | ||
431 | poll_wait(file, &u->evtchn_wait, wait); | |
432 | if (u->ring_cons != u->ring_prod) | |
433 | mask |= POLLIN | POLLRDNORM; | |
434 | if (u->ring_overflow) | |
435 | mask = POLLERR; | |
436 | return mask; | |
437 | } | |
438 | ||
439 | static int evtchn_fasync(int fd, struct file *filp, int on) | |
440 | { | |
441 | struct per_user_data *u = filp->private_data; | |
442 | return fasync_helper(fd, filp, on, &u->evtchn_async_queue); | |
443 | } | |
444 | ||
445 | static int evtchn_open(struct inode *inode, struct file *filp) | |
446 | { | |
447 | struct per_user_data *u; | |
448 | ||
449 | u = kzalloc(sizeof(*u), GFP_KERNEL); | |
450 | if (u == NULL) | |
451 | return -ENOMEM; | |
452 | ||
453 | u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm); | |
454 | if (u->name == NULL) { | |
455 | kfree(u); | |
456 | return -ENOMEM; | |
457 | } | |
458 | ||
459 | init_waitqueue_head(&u->evtchn_wait); | |
460 | ||
461 | u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
462 | if (u->ring == NULL) { | |
463 | kfree(u->name); | |
464 | kfree(u); | |
465 | return -ENOMEM; | |
466 | } | |
467 | ||
0a4666b5 | 468 | mutex_init(&u->bind_mutex); |
f7116284 IC |
469 | mutex_init(&u->ring_cons_mutex); |
470 | ||
471 | filp->private_data = u; | |
472 | ||
6eab04a8 | 473 | return nonseekable_open(inode, filp); |
f7116284 IC |
474 | } |
475 | ||
476 | static int evtchn_release(struct inode *inode, struct file *filp) | |
477 | { | |
478 | int i; | |
479 | struct per_user_data *u = filp->private_data; | |
480 | ||
481 | spin_lock_irq(&port_user_lock); | |
482 | ||
483 | free_page((unsigned long)u->ring); | |
484 | ||
485 | for (i = 0; i < NR_EVENT_CHANNELS; i++) { | |
e3cc067b | 486 | if (get_port_user(i) != u) |
f7116284 IC |
487 | continue; |
488 | ||
3f5e554f | 489 | disable_irq(irq_from_evtchn(i)); |
f7116284 IC |
490 | } |
491 | ||
492 | spin_unlock_irq(&port_user_lock); | |
493 | ||
3f5e554f JF |
494 | for (i = 0; i < NR_EVENT_CHANNELS; i++) { |
495 | if (get_port_user(i) != u) | |
496 | continue; | |
497 | ||
498 | evtchn_unbind_from_user(get_port_user(i), i); | |
499 | } | |
500 | ||
f7116284 IC |
501 | kfree(u->name); |
502 | kfree(u); | |
503 | ||
504 | return 0; | |
505 | } | |
506 | ||
507 | static const struct file_operations evtchn_fops = { | |
508 | .owner = THIS_MODULE, | |
509 | .read = evtchn_read, | |
510 | .write = evtchn_write, | |
511 | .unlocked_ioctl = evtchn_ioctl, | |
512 | .poll = evtchn_poll, | |
513 | .fasync = evtchn_fasync, | |
514 | .open = evtchn_open, | |
515 | .release = evtchn_release, | |
bc7fc5e3 | 516 | .llseek = no_llseek, |
f7116284 IC |
517 | }; |
518 | ||
519 | static struct miscdevice evtchn_miscdev = { | |
520 | .minor = MISC_DYNAMIC_MINOR, | |
376d908f | 521 | .name = "xen/evtchn", |
f7116284 IC |
522 | .fops = &evtchn_fops, |
523 | }; | |
524 | static int __init evtchn_init(void) | |
525 | { | |
526 | int err; | |
527 | ||
528 | if (!xen_domain()) | |
529 | return -ENODEV; | |
530 | ||
93afe0b7 JF |
531 | port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL); |
532 | if (port_user == NULL) | |
533 | return -ENOMEM; | |
534 | ||
f7116284 | 535 | spin_lock_init(&port_user_lock); |
f7116284 | 536 | |
18283ea7 | 537 | /* Create '/dev/xen/evtchn'. */ |
f7116284 IC |
538 | err = misc_register(&evtchn_miscdev); |
539 | if (err != 0) { | |
18283ea7 | 540 | printk(KERN_ERR "Could not register /dev/xen/evtchn\n"); |
f7116284 IC |
541 | return err; |
542 | } | |
543 | ||
544 | printk(KERN_INFO "Event-channel device installed.\n"); | |
545 | ||
546 | return 0; | |
547 | } | |
548 | ||
549 | static void __exit evtchn_cleanup(void) | |
550 | { | |
93afe0b7 JF |
551 | kfree(port_user); |
552 | port_user = NULL; | |
553 | ||
f7116284 IC |
554 | misc_deregister(&evtchn_miscdev); |
555 | } | |
556 | ||
557 | module_init(evtchn_init); | |
558 | module_exit(evtchn_cleanup); | |
559 | ||
560 | MODULE_LICENSE("GPL"); |