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Linux 4.1.16
[linux/fpc-iii.git] / drivers / xen / evtchn.c
blob00f40f051d95668b01ebf6b4c17e6f0e90912198
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 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
35
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>
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>
50 #include <linux/mutex.h>
51 #include <linux/cpu.h>
52
53 #include <xen/xen.h>
54 #include <xen/events.h>
55 #include <xen/evtchn.h>
56 #include <asm/xen/hypervisor.h>
57
58 struct per_user_data {
59 struct mutex bind_mutex; /* serialize bind/unbind operations */
60 struct rb_root evtchns;
61
62 /* Notification ring, accessed via /dev/xen/evtchn. */
63 #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
64 #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
65 evtchn_port_t *ring;
66 unsigned int ring_cons, ring_prod, ring_overflow;
67 struct mutex ring_cons_mutex; /* protect against concurrent readers */
68 spinlock_t ring_prod_lock; /* product against concurrent interrupts */
69
70 /* Processes wait on this queue when ring is empty. */
71 wait_queue_head_t evtchn_wait;
72 struct fasync_struct *evtchn_async_queue;
73 const char *name;
74 };
75
76 struct user_evtchn {
77 struct rb_node node;
78 struct per_user_data *user;
79 unsigned port;
80 bool enabled;
81 };
82
83 static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
84 {
85 struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
86
87 while (*new) {
88 struct user_evtchn *this;
89
90 this = container_of(*new, struct user_evtchn, node);
91
92 parent = *new;
93 if (this->port < evtchn->port)
94 new = &((*new)->rb_left);
95 else if (this->port > evtchn->port)
96 new = &((*new)->rb_right);
97 else
98 return -EEXIST;
99 }
100
101 /* Add new node and rebalance tree. */
102 rb_link_node(&evtchn->node, parent, new);
103 rb_insert_color(&evtchn->node, &u->evtchns);
104
105 return 0;
106 }
107
108 static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
109 {
110 rb_erase(&evtchn->node, &u->evtchns);
111 kfree(evtchn);
112 }
113
114 static struct user_evtchn *find_evtchn(struct per_user_data *u, unsigned port)
115 {
116 struct rb_node *node = u->evtchns.rb_node;
117
118 while (node) {
119 struct user_evtchn *evtchn;
120
121 evtchn = container_of(node, struct user_evtchn, node);
122
123 if (evtchn->port < port)
124 node = node->rb_left;
125 else if (evtchn->port > port)
126 node = node->rb_right;
127 else
128 return evtchn;
129 }
130 return NULL;
131 }
132
133 static irqreturn_t evtchn_interrupt(int irq, void *data)
134 {
135 struct user_evtchn *evtchn = data;
136 struct per_user_data *u = evtchn->user;
137
138 WARN(!evtchn->enabled,
139 "Interrupt for port %d, but apparently not enabled; per-user %p\n",
140 evtchn->port, u);
141
142 disable_irq_nosync(irq);
143 evtchn->enabled = false;
144
145 spin_lock(&u->ring_prod_lock);
146
147 if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
148 u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port;
149 wmb(); /* Ensure ring contents visible */
150 if (u->ring_cons == u->ring_prod++) {
151 wake_up_interruptible(&u->evtchn_wait);
152 kill_fasync(&u->evtchn_async_queue,
153 SIGIO, POLL_IN);
154 }
155 } else
156 u->ring_overflow = 1;
157
158 spin_unlock(&u->ring_prod_lock);
159
160 return IRQ_HANDLED;
161 }
162
163 static ssize_t evtchn_read(struct file *file, char __user *buf,
164 size_t count, loff_t *ppos)
165 {
166 int rc;
167 unsigned int c, p, bytes1 = 0, bytes2 = 0;
168 struct per_user_data *u = file->private_data;
169
170 /* Whole number of ports. */
171 count &= ~(sizeof(evtchn_port_t)-1);
172
173 if (count == 0)
174 return 0;
175
176 if (count > PAGE_SIZE)
177 count = PAGE_SIZE;
178
179 for (;;) {
180 mutex_lock(&u->ring_cons_mutex);
181
182 rc = -EFBIG;
183 if (u->ring_overflow)
184 goto unlock_out;
185
186 c = u->ring_cons;
187 p = u->ring_prod;
188 if (c != p)
189 break;
190
191 mutex_unlock(&u->ring_cons_mutex);
192
193 if (file->f_flags & O_NONBLOCK)
194 return -EAGAIN;
195
196 rc = wait_event_interruptible(u->evtchn_wait,
197 u->ring_cons != u->ring_prod);
198 if (rc)
199 return rc;
200 }
201
202 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
203 if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
204 bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
205 sizeof(evtchn_port_t);
206 bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
207 } else {
208 bytes1 = (p - c) * sizeof(evtchn_port_t);
209 bytes2 = 0;
210 }
211
212 /* Truncate chunks according to caller's maximum byte count. */
213 if (bytes1 > count) {
214 bytes1 = count;
215 bytes2 = 0;
216 } else if ((bytes1 + bytes2) > count) {
217 bytes2 = count - bytes1;
218 }
219
220 rc = -EFAULT;
221 rmb(); /* Ensure that we see the port before we copy it. */
222 if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
223 ((bytes2 != 0) &&
224 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
225 goto unlock_out;
226
227 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
228 rc = bytes1 + bytes2;
229
230 unlock_out:
231 mutex_unlock(&u->ring_cons_mutex);
232 return rc;
233 }
234
235 static ssize_t evtchn_write(struct file *file, const char __user *buf,
236 size_t count, loff_t *ppos)
237 {
238 int rc, i;
239 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
240 struct per_user_data *u = file->private_data;
241
242 if (kbuf == NULL)
243 return -ENOMEM;
244
245 /* Whole number of ports. */
246 count &= ~(sizeof(evtchn_port_t)-1);
247
248 rc = 0;
249 if (count == 0)
250 goto out;
251
252 if (count > PAGE_SIZE)
253 count = PAGE_SIZE;
254
255 rc = -EFAULT;
256 if (copy_from_user(kbuf, buf, count) != 0)
257 goto out;
258
259 mutex_lock(&u->bind_mutex);
260
261 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
262 unsigned port = kbuf[i];
263 struct user_evtchn *evtchn;
264
265 evtchn = find_evtchn(u, port);
266 if (evtchn && !evtchn->enabled) {
267 evtchn->enabled = true;
268 enable_irq(irq_from_evtchn(port));
269 }
270 }
271
272 mutex_unlock(&u->bind_mutex);
273
274 rc = count;
275
276 out:
277 free_page((unsigned long)kbuf);
278 return rc;
279 }
280
281 static int evtchn_bind_to_user(struct per_user_data *u, int port)
282 {
283 struct user_evtchn *evtchn;
284 struct evtchn_close close;
285 int rc = 0;
286
287 /*
288 * Ports are never reused, so every caller should pass in a
289 * unique port.
290 *
291 * (Locking not necessary because we haven't registered the
292 * interrupt handler yet, and our caller has already
293 * serialized bind operations.)
294 */
295
296 evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
297 if (!evtchn)
298 return -ENOMEM;
299
300 evtchn->user = u;
301 evtchn->port = port;
302 evtchn->enabled = true; /* start enabled */
303
304 rc = add_evtchn(u, evtchn);
305 if (rc < 0)
306 goto err;
307
308 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
309 u->name, evtchn);
310 if (rc < 0)
311 goto err;
312
313 rc = evtchn_make_refcounted(port);
314 return rc;
315
316 err:
317 /* bind failed, should close the port now */
318 close.port = port;
319 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
320 BUG();
321 del_evtchn(u, evtchn);
322 return rc;
323 }
324
325 static void evtchn_unbind_from_user(struct per_user_data *u,
326 struct user_evtchn *evtchn)
327 {
328 int irq = irq_from_evtchn(evtchn->port);
329
330 BUG_ON(irq < 0);
331
332 unbind_from_irqhandler(irq, evtchn);
333
334 del_evtchn(u, evtchn);
335 }
336
337 static long evtchn_ioctl(struct file *file,
338 unsigned int cmd, unsigned long arg)
339 {
340 int rc;
341 struct per_user_data *u = file->private_data;
342 void __user *uarg = (void __user *) arg;
343
344 /* Prevent bind from racing with unbind */
345 mutex_lock(&u->bind_mutex);
346
347 switch (cmd) {
348 case IOCTL_EVTCHN_BIND_VIRQ: {
349 struct ioctl_evtchn_bind_virq bind;
350 struct evtchn_bind_virq bind_virq;
351
352 rc = -EFAULT;
353 if (copy_from_user(&bind, uarg, sizeof(bind)))
354 break;
355
356 bind_virq.virq = bind.virq;
357 bind_virq.vcpu = 0;
358 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
359 &bind_virq);
360 if (rc != 0)
361 break;
362
363 rc = evtchn_bind_to_user(u, bind_virq.port);
364 if (rc == 0)
365 rc = bind_virq.port;
366 break;
367 }
368
369 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
370 struct ioctl_evtchn_bind_interdomain bind;
371 struct evtchn_bind_interdomain bind_interdomain;
372
373 rc = -EFAULT;
374 if (copy_from_user(&bind, uarg, sizeof(bind)))
375 break;
376
377 bind_interdomain.remote_dom = bind.remote_domain;
378 bind_interdomain.remote_port = bind.remote_port;
379 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
380 &bind_interdomain);
381 if (rc != 0)
382 break;
383
384 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
385 if (rc == 0)
386 rc = bind_interdomain.local_port;
387 break;
388 }
389
390 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
391 struct ioctl_evtchn_bind_unbound_port bind;
392 struct evtchn_alloc_unbound alloc_unbound;
393
394 rc = -EFAULT;
395 if (copy_from_user(&bind, uarg, sizeof(bind)))
396 break;
397
398 alloc_unbound.dom = DOMID_SELF;
399 alloc_unbound.remote_dom = bind.remote_domain;
400 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
401 &alloc_unbound);
402 if (rc != 0)
403 break;
404
405 rc = evtchn_bind_to_user(u, alloc_unbound.port);
406 if (rc == 0)
407 rc = alloc_unbound.port;
408 break;
409 }
410
411 case IOCTL_EVTCHN_UNBIND: {
412 struct ioctl_evtchn_unbind unbind;
413 struct user_evtchn *evtchn;
414
415 rc = -EFAULT;
416 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
417 break;
418
419 rc = -EINVAL;
420 if (unbind.port >= xen_evtchn_nr_channels())
421 break;
422
423 rc = -ENOTCONN;
424 evtchn = find_evtchn(u, unbind.port);
425 if (!evtchn)
426 break;
427
428 disable_irq(irq_from_evtchn(unbind.port));
429 evtchn_unbind_from_user(u, evtchn);
430 rc = 0;
431 break;
432 }
433
434 case IOCTL_EVTCHN_NOTIFY: {
435 struct ioctl_evtchn_notify notify;
436 struct user_evtchn *evtchn;
437
438 rc = -EFAULT;
439 if (copy_from_user(&notify, uarg, sizeof(notify)))
440 break;
441
442 rc = -ENOTCONN;
443 evtchn = find_evtchn(u, notify.port);
444 if (evtchn) {
445 notify_remote_via_evtchn(notify.port);
446 rc = 0;
447 }
448 break;
449 }
450
451 case IOCTL_EVTCHN_RESET: {
452 /* Initialise the ring to empty. Clear errors. */
453 mutex_lock(&u->ring_cons_mutex);
454 spin_lock_irq(&u->ring_prod_lock);
455 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
456 spin_unlock_irq(&u->ring_prod_lock);
457 mutex_unlock(&u->ring_cons_mutex);
458 rc = 0;
459 break;
460 }
461
462 default:
463 rc = -ENOSYS;
464 break;
465 }
466 mutex_unlock(&u->bind_mutex);
467
468 return rc;
469 }
470
471 static unsigned int evtchn_poll(struct file *file, poll_table *wait)
472 {
473 unsigned int mask = POLLOUT | POLLWRNORM;
474 struct per_user_data *u = file->private_data;
475
476 poll_wait(file, &u->evtchn_wait, wait);
477 if (u->ring_cons != u->ring_prod)
478 mask |= POLLIN | POLLRDNORM;
479 if (u->ring_overflow)
480 mask = POLLERR;
481 return mask;
482 }
483
484 static int evtchn_fasync(int fd, struct file *filp, int on)
485 {
486 struct per_user_data *u = filp->private_data;
487 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
488 }
489
490 static int evtchn_open(struct inode *inode, struct file *filp)
491 {
492 struct per_user_data *u;
493
494 u = kzalloc(sizeof(*u), GFP_KERNEL);
495 if (u == NULL)
496 return -ENOMEM;
497
498 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
499 if (u->name == NULL) {
500 kfree(u);
501 return -ENOMEM;
502 }
503
504 init_waitqueue_head(&u->evtchn_wait);
505
506 u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
507 if (u->ring == NULL) {
508 kfree(u->name);
509 kfree(u);
510 return -ENOMEM;
511 }
512
513 mutex_init(&u->bind_mutex);
514 mutex_init(&u->ring_cons_mutex);
515 spin_lock_init(&u->ring_prod_lock);
516
517 filp->private_data = u;
518
519 return nonseekable_open(inode, filp);
520 }
521
522 static int evtchn_release(struct inode *inode, struct file *filp)
523 {
524 struct per_user_data *u = filp->private_data;
525 struct rb_node *node;
526
527 while ((node = u->evtchns.rb_node)) {
528 struct user_evtchn *evtchn;
529
530 evtchn = rb_entry(node, struct user_evtchn, node);
531 disable_irq(irq_from_evtchn(evtchn->port));
532 evtchn_unbind_from_user(u, evtchn);
533 }
534
535 free_page((unsigned long)u->ring);
536 kfree(u->name);
537 kfree(u);
538
539 return 0;
540 }
541
542 static const struct file_operations evtchn_fops = {
543 .owner = THIS_MODULE,
544 .read = evtchn_read,
545 .write = evtchn_write,
546 .unlocked_ioctl = evtchn_ioctl,
547 .poll = evtchn_poll,
548 .fasync = evtchn_fasync,
549 .open = evtchn_open,
550 .release = evtchn_release,
551 .llseek = no_llseek,
552 };
553
554 static struct miscdevice evtchn_miscdev = {
555 .minor = MISC_DYNAMIC_MINOR,
556 .name = "xen/evtchn",
557 .fops = &evtchn_fops,
558 };
559 static int __init evtchn_init(void)
560 {
561 int err;
562
563 if (!xen_domain())
564 return -ENODEV;
565
566 /* Create '/dev/xen/evtchn'. */
567 err = misc_register(&evtchn_miscdev);
568 if (err != 0) {
569 pr_err("Could not register /dev/xen/evtchn\n");
570 return err;
571 }
572
573 pr_info("Event-channel device installed\n");
574
575 return 0;
576 }
577
578 static void __exit evtchn_cleanup(void)
579 {
580 misc_deregister(&evtchn_miscdev);
581 }
582
583 module_init(evtchn_init);
584 module_exit(evtchn_cleanup);
585
586 MODULE_LICENSE("GPL");
Linux with added FPC-III support