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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 | ||
283c0972 JP |
34 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
35 | ||
f7116284 IC |
36 | #include <linux/module.h> |
37 | #include <linux/kernel.h> | |
38 | #include <linux/sched.h> | |
39 | #include <linux/slab.h> | |
40 | #include <linux/string.h> | |
41 | #include <linux/errno.h> | |
42 | #include <linux/fs.h> | |
f7116284 IC |
43 | #include <linux/miscdevice.h> |
44 | #include <linux/major.h> | |
45 | #include <linux/proc_fs.h> | |
46 | #include <linux/stat.h> | |
47 | #include <linux/poll.h> | |
48 | #include <linux/irq.h> | |
49 | #include <linux/init.h> | |
f7116284 IC |
50 | #include <linux/mutex.h> |
51 | #include <linux/cpu.h> | |
1ccbf534 JF |
52 | |
53 | #include <xen/xen.h> | |
f7116284 IC |
54 | #include <xen/events.h> |
55 | #include <xen/evtchn.h> | |
56 | #include <asm/xen/hypervisor.h> | |
57 | ||
58 | struct per_user_data { | |
0a4666b5 JF |
59 | struct mutex bind_mutex; /* serialize bind/unbind operations */ |
60 | ||
f7116284 IC |
61 | /* Notification ring, accessed via /dev/xen/evtchn. */ |
62 | #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) | |
63 | #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) | |
64 | evtchn_port_t *ring; | |
65 | unsigned int ring_cons, ring_prod, ring_overflow; | |
66 | struct mutex ring_cons_mutex; /* protect against concurrent readers */ | |
67 | ||
68 | /* Processes wait on this queue when ring is empty. */ | |
69 | wait_queue_head_t evtchn_wait; | |
70 | struct fasync_struct *evtchn_async_queue; | |
71 | const char *name; | |
72 | }; | |
73 | ||
e3cc067b JF |
74 | /* |
75 | * Who's bound to each port? This is logically an array of struct | |
76 | * per_user_data *, but we encode the current enabled-state in bit 0. | |
77 | */ | |
93afe0b7 | 78 | static unsigned long *port_user; |
0a4666b5 | 79 | static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ |
f7116284 | 80 | |
e3cc067b JF |
81 | static inline struct per_user_data *get_port_user(unsigned port) |
82 | { | |
83 | return (struct per_user_data *)(port_user[port] & ~1); | |
84 | } | |
85 | ||
86 | static inline void set_port_user(unsigned port, struct per_user_data *u) | |
87 | { | |
88 | port_user[port] = (unsigned long)u; | |
89 | } | |
90 | ||
91 | static inline bool get_port_enabled(unsigned port) | |
92 | { | |
93 | return port_user[port] & 1; | |
94 | } | |
95 | ||
96 | static inline void set_port_enabled(unsigned port, bool enabled) | |
97 | { | |
98 | if (enabled) | |
99 | port_user[port] |= 1; | |
100 | else | |
101 | port_user[port] &= ~1; | |
102 | } | |
103 | ||
70697d54 | 104 | static irqreturn_t evtchn_interrupt(int irq, void *data) |
f7116284 IC |
105 | { |
106 | unsigned int port = (unsigned long)data; | |
107 | struct per_user_data *u; | |
108 | ||
109 | spin_lock(&port_user_lock); | |
110 | ||
e3cc067b JF |
111 | u = get_port_user(port); |
112 | ||
0edce91d JF |
113 | WARN(!get_port_enabled(port), |
114 | "Interrupt for port %d, but apparently not enabled; per-user %p\n", | |
115 | port, u); | |
f7116284 IC |
116 | |
117 | disable_irq_nosync(irq); | |
e3cc067b | 118 | set_port_enabled(port, false); |
f7116284 IC |
119 | |
120 | if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { | |
121 | u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port; | |
122 | wmb(); /* Ensure ring contents visible */ | |
123 | if (u->ring_cons == u->ring_prod++) { | |
124 | wake_up_interruptible(&u->evtchn_wait); | |
125 | kill_fasync(&u->evtchn_async_queue, | |
126 | SIGIO, POLL_IN); | |
127 | } | |
e3cc067b | 128 | } else |
f7116284 | 129 | u->ring_overflow = 1; |
f7116284 IC |
130 | |
131 | spin_unlock(&port_user_lock); | |
132 | ||
133 | return IRQ_HANDLED; | |
134 | } | |
135 | ||
136 | static ssize_t evtchn_read(struct file *file, char __user *buf, | |
137 | size_t count, loff_t *ppos) | |
138 | { | |
139 | int rc; | |
140 | unsigned int c, p, bytes1 = 0, bytes2 = 0; | |
141 | struct per_user_data *u = file->private_data; | |
142 | ||
143 | /* Whole number of ports. */ | |
144 | count &= ~(sizeof(evtchn_port_t)-1); | |
145 | ||
146 | if (count == 0) | |
147 | return 0; | |
148 | ||
149 | if (count > PAGE_SIZE) | |
150 | count = PAGE_SIZE; | |
151 | ||
152 | for (;;) { | |
153 | mutex_lock(&u->ring_cons_mutex); | |
154 | ||
155 | rc = -EFBIG; | |
156 | if (u->ring_overflow) | |
157 | goto unlock_out; | |
158 | ||
159 | c = u->ring_cons; | |
160 | p = u->ring_prod; | |
161 | if (c != p) | |
162 | break; | |
163 | ||
164 | mutex_unlock(&u->ring_cons_mutex); | |
165 | ||
166 | if (file->f_flags & O_NONBLOCK) | |
167 | return -EAGAIN; | |
168 | ||
169 | rc = wait_event_interruptible(u->evtchn_wait, | |
170 | u->ring_cons != u->ring_prod); | |
171 | if (rc) | |
172 | return rc; | |
173 | } | |
174 | ||
175 | /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ | |
176 | if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { | |
177 | bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * | |
178 | sizeof(evtchn_port_t); | |
179 | bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); | |
180 | } else { | |
181 | bytes1 = (p - c) * sizeof(evtchn_port_t); | |
182 | bytes2 = 0; | |
183 | } | |
184 | ||
185 | /* Truncate chunks according to caller's maximum byte count. */ | |
186 | if (bytes1 > count) { | |
187 | bytes1 = count; | |
188 | bytes2 = 0; | |
189 | } else if ((bytes1 + bytes2) > count) { | |
190 | bytes2 = count - bytes1; | |
191 | } | |
192 | ||
193 | rc = -EFAULT; | |
194 | rmb(); /* Ensure that we see the port before we copy it. */ | |
195 | if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || | |
196 | ((bytes2 != 0) && | |
197 | copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) | |
198 | goto unlock_out; | |
199 | ||
200 | u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t); | |
201 | rc = bytes1 + bytes2; | |
202 | ||
203 | unlock_out: | |
204 | mutex_unlock(&u->ring_cons_mutex); | |
205 | return rc; | |
206 | } | |
207 | ||
208 | static ssize_t evtchn_write(struct file *file, const char __user *buf, | |
209 | size_t count, loff_t *ppos) | |
210 | { | |
211 | int rc, i; | |
212 | evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
213 | struct per_user_data *u = file->private_data; | |
214 | ||
215 | if (kbuf == NULL) | |
216 | return -ENOMEM; | |
217 | ||
218 | /* Whole number of ports. */ | |
219 | count &= ~(sizeof(evtchn_port_t)-1); | |
220 | ||
221 | rc = 0; | |
222 | if (count == 0) | |
223 | goto out; | |
224 | ||
225 | if (count > PAGE_SIZE) | |
226 | count = PAGE_SIZE; | |
227 | ||
228 | rc = -EFAULT; | |
229 | if (copy_from_user(kbuf, buf, count) != 0) | |
230 | goto out; | |
231 | ||
232 | spin_lock_irq(&port_user_lock); | |
e3cc067b JF |
233 | |
234 | for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) { | |
235 | unsigned port = kbuf[i]; | |
236 | ||
237 | if (port < NR_EVENT_CHANNELS && | |
238 | get_port_user(port) == u && | |
239 | !get_port_enabled(port)) { | |
240 | set_port_enabled(port, true); | |
241 | enable_irq(irq_from_evtchn(port)); | |
242 | } | |
243 | } | |
244 | ||
f7116284 IC |
245 | spin_unlock_irq(&port_user_lock); |
246 | ||
247 | rc = count; | |
248 | ||
249 | out: | |
250 | free_page((unsigned long)kbuf); | |
251 | return rc; | |
252 | } | |
253 | ||
254 | static int evtchn_bind_to_user(struct per_user_data *u, int port) | |
255 | { | |
f7116284 IC |
256 | int rc = 0; |
257 | ||
0a4666b5 JF |
258 | /* |
259 | * Ports are never reused, so every caller should pass in a | |
260 | * unique port. | |
261 | * | |
262 | * (Locking not necessary because we haven't registered the | |
263 | * interrupt handler yet, and our caller has already | |
264 | * serialized bind operations.) | |
265 | */ | |
e3cc067b JF |
266 | BUG_ON(get_port_user(port) != NULL); |
267 | set_port_user(port, u); | |
0edce91d | 268 | set_port_enabled(port, true); /* start enabled */ |
f7116284 | 269 | |
0a4666b5 JF |
270 | rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, |
271 | u->name, (void *)(unsigned long)port); | |
272 | if (rc >= 0) | |
420eb554 | 273 | rc = evtchn_make_refcounted(port); |
e7e44e44 WL |
274 | else { |
275 | /* bind failed, should close the port now */ | |
276 | struct evtchn_close close; | |
277 | close.port = port; | |
278 | if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0) | |
279 | BUG(); | |
280 | set_port_user(port, NULL); | |
281 | } | |
0a4666b5 | 282 | |
f7116284 IC |
283 | return rc; |
284 | } | |
285 | ||
286 | static void evtchn_unbind_from_user(struct per_user_data *u, int port) | |
287 | { | |
288 | int irq = irq_from_evtchn(port); | |
289 | ||
e7e44e44 WL |
290 | BUG_ON(irq < 0); |
291 | ||
f7116284 | 292 | unbind_from_irqhandler(irq, (void *)(unsigned long)port); |
0a4666b5 | 293 | |
e3cc067b | 294 | set_port_user(port, NULL); |
f7116284 IC |
295 | } |
296 | ||
297 | static long evtchn_ioctl(struct file *file, | |
298 | unsigned int cmd, unsigned long arg) | |
299 | { | |
300 | int rc; | |
301 | struct per_user_data *u = file->private_data; | |
302 | void __user *uarg = (void __user *) arg; | |
303 | ||
0a4666b5 JF |
304 | /* Prevent bind from racing with unbind */ |
305 | mutex_lock(&u->bind_mutex); | |
306 | ||
f7116284 IC |
307 | switch (cmd) { |
308 | case IOCTL_EVTCHN_BIND_VIRQ: { | |
309 | struct ioctl_evtchn_bind_virq bind; | |
310 | struct evtchn_bind_virq bind_virq; | |
311 | ||
312 | rc = -EFAULT; | |
313 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
314 | break; | |
315 | ||
316 | bind_virq.virq = bind.virq; | |
317 | bind_virq.vcpu = 0; | |
318 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, | |
319 | &bind_virq); | |
320 | if (rc != 0) | |
321 | break; | |
322 | ||
323 | rc = evtchn_bind_to_user(u, bind_virq.port); | |
324 | if (rc == 0) | |
325 | rc = bind_virq.port; | |
326 | break; | |
327 | } | |
328 | ||
329 | case IOCTL_EVTCHN_BIND_INTERDOMAIN: { | |
330 | struct ioctl_evtchn_bind_interdomain bind; | |
331 | struct evtchn_bind_interdomain bind_interdomain; | |
332 | ||
333 | rc = -EFAULT; | |
334 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
335 | break; | |
336 | ||
337 | bind_interdomain.remote_dom = bind.remote_domain; | |
338 | bind_interdomain.remote_port = bind.remote_port; | |
339 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, | |
340 | &bind_interdomain); | |
341 | if (rc != 0) | |
342 | break; | |
343 | ||
344 | rc = evtchn_bind_to_user(u, bind_interdomain.local_port); | |
345 | if (rc == 0) | |
346 | rc = bind_interdomain.local_port; | |
347 | break; | |
348 | } | |
349 | ||
350 | case IOCTL_EVTCHN_BIND_UNBOUND_PORT: { | |
351 | struct ioctl_evtchn_bind_unbound_port bind; | |
352 | struct evtchn_alloc_unbound alloc_unbound; | |
353 | ||
354 | rc = -EFAULT; | |
355 | if (copy_from_user(&bind, uarg, sizeof(bind))) | |
356 | break; | |
357 | ||
358 | alloc_unbound.dom = DOMID_SELF; | |
359 | alloc_unbound.remote_dom = bind.remote_domain; | |
360 | rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, | |
361 | &alloc_unbound); | |
362 | if (rc != 0) | |
363 | break; | |
364 | ||
365 | rc = evtchn_bind_to_user(u, alloc_unbound.port); | |
366 | if (rc == 0) | |
367 | rc = alloc_unbound.port; | |
368 | break; | |
369 | } | |
370 | ||
371 | case IOCTL_EVTCHN_UNBIND: { | |
372 | struct ioctl_evtchn_unbind unbind; | |
373 | ||
374 | rc = -EFAULT; | |
375 | if (copy_from_user(&unbind, uarg, sizeof(unbind))) | |
376 | break; | |
377 | ||
378 | rc = -EINVAL; | |
379 | if (unbind.port >= NR_EVENT_CHANNELS) | |
380 | break; | |
381 | ||
f7116284 | 382 | rc = -ENOTCONN; |
179fbd5a | 383 | if (get_port_user(unbind.port) != u) |
f7116284 | 384 | break; |
f7116284 | 385 | |
3f5e554f | 386 | disable_irq(irq_from_evtchn(unbind.port)); |
f7116284 | 387 | |
3f5e554f JF |
388 | evtchn_unbind_from_user(u, unbind.port); |
389 | ||
f7116284 IC |
390 | rc = 0; |
391 | break; | |
392 | } | |
393 | ||
394 | case IOCTL_EVTCHN_NOTIFY: { | |
395 | struct ioctl_evtchn_notify notify; | |
396 | ||
397 | rc = -EFAULT; | |
398 | if (copy_from_user(¬ify, uarg, sizeof(notify))) | |
399 | break; | |
400 | ||
401 | if (notify.port >= NR_EVENT_CHANNELS) { | |
402 | rc = -EINVAL; | |
e3cc067b | 403 | } else if (get_port_user(notify.port) != u) { |
f7116284 IC |
404 | rc = -ENOTCONN; |
405 | } else { | |
406 | notify_remote_via_evtchn(notify.port); | |
407 | rc = 0; | |
408 | } | |
409 | break; | |
410 | } | |
411 | ||
412 | case IOCTL_EVTCHN_RESET: { | |
413 | /* Initialise the ring to empty. Clear errors. */ | |
414 | mutex_lock(&u->ring_cons_mutex); | |
415 | spin_lock_irq(&port_user_lock); | |
416 | u->ring_cons = u->ring_prod = u->ring_overflow = 0; | |
417 | spin_unlock_irq(&port_user_lock); | |
418 | mutex_unlock(&u->ring_cons_mutex); | |
419 | rc = 0; | |
420 | break; | |
421 | } | |
422 | ||
423 | default: | |
424 | rc = -ENOSYS; | |
425 | break; | |
426 | } | |
0a4666b5 | 427 | mutex_unlock(&u->bind_mutex); |
f7116284 IC |
428 | |
429 | return rc; | |
430 | } | |
431 | ||
432 | static unsigned int evtchn_poll(struct file *file, poll_table *wait) | |
433 | { | |
434 | unsigned int mask = POLLOUT | POLLWRNORM; | |
435 | struct per_user_data *u = file->private_data; | |
436 | ||
437 | poll_wait(file, &u->evtchn_wait, wait); | |
438 | if (u->ring_cons != u->ring_prod) | |
439 | mask |= POLLIN | POLLRDNORM; | |
440 | if (u->ring_overflow) | |
441 | mask = POLLERR; | |
442 | return mask; | |
443 | } | |
444 | ||
445 | static int evtchn_fasync(int fd, struct file *filp, int on) | |
446 | { | |
447 | struct per_user_data *u = filp->private_data; | |
448 | return fasync_helper(fd, filp, on, &u->evtchn_async_queue); | |
449 | } | |
450 | ||
451 | static int evtchn_open(struct inode *inode, struct file *filp) | |
452 | { | |
453 | struct per_user_data *u; | |
454 | ||
455 | u = kzalloc(sizeof(*u), GFP_KERNEL); | |
456 | if (u == NULL) | |
457 | return -ENOMEM; | |
458 | ||
459 | u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm); | |
460 | if (u->name == NULL) { | |
461 | kfree(u); | |
462 | return -ENOMEM; | |
463 | } | |
464 | ||
465 | init_waitqueue_head(&u->evtchn_wait); | |
466 | ||
467 | u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); | |
468 | if (u->ring == NULL) { | |
469 | kfree(u->name); | |
470 | kfree(u); | |
471 | return -ENOMEM; | |
472 | } | |
473 | ||
0a4666b5 | 474 | mutex_init(&u->bind_mutex); |
f7116284 IC |
475 | mutex_init(&u->ring_cons_mutex); |
476 | ||
477 | filp->private_data = u; | |
478 | ||
6eab04a8 | 479 | return nonseekable_open(inode, filp); |
f7116284 IC |
480 | } |
481 | ||
482 | static int evtchn_release(struct inode *inode, struct file *filp) | |
483 | { | |
484 | int i; | |
485 | struct per_user_data *u = filp->private_data; | |
486 | ||
f7116284 | 487 | for (i = 0; i < NR_EVENT_CHANNELS; i++) { |
e3cc067b | 488 | if (get_port_user(i) != u) |
f7116284 IC |
489 | continue; |
490 | ||
3f5e554f | 491 | disable_irq(irq_from_evtchn(i)); |
3f5e554f JF |
492 | evtchn_unbind_from_user(get_port_user(i), i); |
493 | } | |
494 | ||
179fbd5a | 495 | free_page((unsigned long)u->ring); |
f7116284 IC |
496 | kfree(u->name); |
497 | kfree(u); | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | static const struct file_operations evtchn_fops = { | |
503 | .owner = THIS_MODULE, | |
504 | .read = evtchn_read, | |
505 | .write = evtchn_write, | |
506 | .unlocked_ioctl = evtchn_ioctl, | |
507 | .poll = evtchn_poll, | |
508 | .fasync = evtchn_fasync, | |
509 | .open = evtchn_open, | |
510 | .release = evtchn_release, | |
bc7fc5e3 | 511 | .llseek = no_llseek, |
f7116284 IC |
512 | }; |
513 | ||
514 | static struct miscdevice evtchn_miscdev = { | |
515 | .minor = MISC_DYNAMIC_MINOR, | |
376d908f | 516 | .name = "xen/evtchn", |
f7116284 IC |
517 | .fops = &evtchn_fops, |
518 | }; | |
519 | static int __init evtchn_init(void) | |
520 | { | |
521 | int err; | |
522 | ||
523 | if (!xen_domain()) | |
524 | return -ENODEV; | |
525 | ||
93afe0b7 JF |
526 | port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL); |
527 | if (port_user == NULL) | |
528 | return -ENOMEM; | |
529 | ||
f7116284 | 530 | spin_lock_init(&port_user_lock); |
f7116284 | 531 | |
18283ea7 | 532 | /* Create '/dev/xen/evtchn'. */ |
f7116284 IC |
533 | err = misc_register(&evtchn_miscdev); |
534 | if (err != 0) { | |
283c0972 | 535 | pr_err("Could not register /dev/xen/evtchn\n"); |
f7116284 IC |
536 | return err; |
537 | } | |
538 | ||
283c0972 | 539 | pr_info("Event-channel device installed\n"); |
f7116284 IC |
540 | |
541 | return 0; | |
542 | } | |
543 | ||
544 | static void __exit evtchn_cleanup(void) | |
545 | { | |
93afe0b7 JF |
546 | kfree(port_user); |
547 | port_user = NULL; | |
548 | ||
f7116284 IC |
549 | misc_deregister(&evtchn_miscdev); |
550 | } | |
551 | ||
552 | module_init(evtchn_init); | |
553 | module_exit(evtchn_cleanup); | |
554 | ||
555 | MODULE_LICENSE("GPL"); |