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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#include <linux/mm.h>
53#include <linux/vmalloc.h>
54
55#include <xen/xen.h>
56#include <xen/events.h>
57#include <xen/evtchn.h>
58#include <xen/xen-ops.h>
59#include <asm/xen/hypervisor.h>
60
61struct per_user_data {
62 struct mutex bind_mutex; /* serialize bind/unbind operations */
63 struct rb_root evtchns;
64 unsigned int nr_evtchns;
65
66 /* Notification ring, accessed via /dev/xen/evtchn. */
67 unsigned int ring_size;
68 evtchn_port_t *ring;
69 unsigned int ring_cons, ring_prod, ring_overflow;
70 struct mutex ring_cons_mutex; /* protect against concurrent readers */
71 spinlock_t ring_prod_lock; /* product against concurrent interrupts */
72
73 /* Processes wait on this queue when ring is empty. */
74 wait_queue_head_t evtchn_wait;
75 struct fasync_struct *evtchn_async_queue;
76 const char *name;
77
78 domid_t restrict_domid;
79};
80
81#define UNRESTRICTED_DOMID ((domid_t)-1)
82
83struct user_evtchn {
84 struct rb_node node;
85 struct per_user_data *user;
86 evtchn_port_t port;
87 bool enabled;
88};
89
90static void evtchn_free_ring(evtchn_port_t *ring)
91{
92 kvfree(ring);
93}
94
95static unsigned int evtchn_ring_offset(struct per_user_data *u,
96 unsigned int idx)
97{
98 return idx & (u->ring_size - 1);
99}
100
101static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
102 unsigned int idx)
103{
104 return u->ring + evtchn_ring_offset(u, idx);
105}
106
107static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
108{
109 struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
110
111 u->nr_evtchns++;
112
113 while (*new) {
114 struct user_evtchn *this;
115
116 this = rb_entry(*new, struct user_evtchn, node);
117
118 parent = *new;
119 if (this->port < evtchn->port)
120 new = &((*new)->rb_left);
121 else if (this->port > evtchn->port)
122 new = &((*new)->rb_right);
123 else
124 return -EEXIST;
125 }
126
127 /* Add new node and rebalance tree. */
128 rb_link_node(&evtchn->node, parent, new);
129 rb_insert_color(&evtchn->node, &u->evtchns);
130
131 return 0;
132}
133
134static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
135{
136 u->nr_evtchns--;
137 rb_erase(&evtchn->node, &u->evtchns);
138 kfree(evtchn);
139}
140
141static struct user_evtchn *find_evtchn(struct per_user_data *u,
142 evtchn_port_t port)
143{
144 struct rb_node *node = u->evtchns.rb_node;
145
146 while (node) {
147 struct user_evtchn *evtchn;
148
149 evtchn = rb_entry(node, struct user_evtchn, node);
150
151 if (evtchn->port < port)
152 node = node->rb_left;
153 else if (evtchn->port > port)
154 node = node->rb_right;
155 else
156 return evtchn;
157 }
158 return NULL;
159}
160
161static irqreturn_t evtchn_interrupt(int irq, void *data)
162{
163 struct user_evtchn *evtchn = data;
164 struct per_user_data *u = evtchn->user;
165 unsigned int prod, cons;
166
167 WARN(!evtchn->enabled,
168 "Interrupt for port %u, but apparently not enabled; per-user %p\n",
169 evtchn->port, u);
170
171 evtchn->enabled = false;
172
173 spin_lock(&u->ring_prod_lock);
174
175 prod = READ_ONCE(u->ring_prod);
176 cons = READ_ONCE(u->ring_cons);
177
178 if ((prod - cons) < u->ring_size) {
179 *evtchn_ring_entry(u, prod) = evtchn->port;
180 smp_wmb(); /* Ensure ring contents visible */
181 WRITE_ONCE(u->ring_prod, prod + 1);
182 if (cons == prod) {
183 wake_up_interruptible(&u->evtchn_wait);
184 kill_fasync(&u->evtchn_async_queue,
185 SIGIO, POLL_IN);
186 }
187 } else
188 u->ring_overflow = 1;
189
190 spin_unlock(&u->ring_prod_lock);
191
192 return IRQ_HANDLED;
193}
194
195static ssize_t evtchn_read(struct file *file, char __user *buf,
196 size_t count, loff_t *ppos)
197{
198 int rc;
199 unsigned int c, p, bytes1 = 0, bytes2 = 0;
200 struct per_user_data *u = file->private_data;
201
202 /* Whole number of ports. */
203 count &= ~(sizeof(evtchn_port_t)-1);
204
205 if (count == 0)
206 return 0;
207
208 if (count > PAGE_SIZE)
209 count = PAGE_SIZE;
210
211 for (;;) {
212 mutex_lock(&u->ring_cons_mutex);
213
214 rc = -EFBIG;
215 if (u->ring_overflow)
216 goto unlock_out;
217
218 c = READ_ONCE(u->ring_cons);
219 p = READ_ONCE(u->ring_prod);
220 if (c != p)
221 break;
222
223 mutex_unlock(&u->ring_cons_mutex);
224
225 if (file->f_flags & O_NONBLOCK)
226 return -EAGAIN;
227
228 rc = wait_event_interruptible(u->evtchn_wait,
229 READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));
230 if (rc)
231 return rc;
232 }
233
234 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
235 if (((c ^ p) & u->ring_size) != 0) {
236 bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
237 sizeof(evtchn_port_t);
238 bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
239 } else {
240 bytes1 = (p - c) * sizeof(evtchn_port_t);
241 bytes2 = 0;
242 }
243
244 /* Truncate chunks according to caller's maximum byte count. */
245 if (bytes1 > count) {
246 bytes1 = count;
247 bytes2 = 0;
248 } else if ((bytes1 + bytes2) > count) {
249 bytes2 = count - bytes1;
250 }
251
252 rc = -EFAULT;
253 smp_rmb(); /* Ensure that we see the port before we copy it. */
254 if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
255 ((bytes2 != 0) &&
256 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
257 goto unlock_out;
258
259 WRITE_ONCE(u->ring_cons, c + (bytes1 + bytes2) / sizeof(evtchn_port_t));
260 rc = bytes1 + bytes2;
261
262 unlock_out:
263 mutex_unlock(&u->ring_cons_mutex);
264 return rc;
265}
266
267static ssize_t evtchn_write(struct file *file, const char __user *buf,
268 size_t count, loff_t *ppos)
269{
270 int rc, i;
271 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
272 struct per_user_data *u = file->private_data;
273
274 if (kbuf == NULL)
275 return -ENOMEM;
276
277 /* Whole number of ports. */
278 count &= ~(sizeof(evtchn_port_t)-1);
279
280 rc = 0;
281 if (count == 0)
282 goto out;
283
284 if (count > PAGE_SIZE)
285 count = PAGE_SIZE;
286
287 rc = -EFAULT;
288 if (copy_from_user(kbuf, buf, count) != 0)
289 goto out;
290
291 mutex_lock(&u->bind_mutex);
292
293 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
294 evtchn_port_t port = kbuf[i];
295 struct user_evtchn *evtchn;
296
297 evtchn = find_evtchn(u, port);
298 if (evtchn && !evtchn->enabled) {
299 evtchn->enabled = true;
300 xen_irq_lateeoi(irq_from_evtchn(port), 0);
301 }
302 }
303
304 mutex_unlock(&u->bind_mutex);
305
306 rc = count;
307
308 out:
309 free_page((unsigned long)kbuf);
310 return rc;
311}
312
313static int evtchn_resize_ring(struct per_user_data *u)
314{
315 unsigned int new_size;
316 evtchn_port_t *new_ring, *old_ring;
317
318 /*
319 * Ensure the ring is large enough to capture all possible
320 * events. i.e., one free slot for each bound event.
321 */
322 if (u->nr_evtchns <= u->ring_size)
323 return 0;
324
325 if (u->ring_size == 0)
326 new_size = 64;
327 else
328 new_size = 2 * u->ring_size;
329
330 new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
331 if (!new_ring)
332 return -ENOMEM;
333
334 old_ring = u->ring;
335
336 /*
337 * Access to the ring contents is serialized by either the
338 * prod /or/ cons lock so take both when resizing.
339 */
340 mutex_lock(&u->ring_cons_mutex);
341 spin_lock_irq(&u->ring_prod_lock);
342
343 /*
344 * Copy the old ring contents to the new ring.
345 *
346 * To take care of wrapping, a full ring, and the new index
347 * pointing into the second half, simply copy the old contents
348 * twice.
349 *
350 * +---------+ +------------------+
351 * |34567 12| -> |34567 1234567 12|
352 * +-----p-c-+ +-------c------p---+
353 */
354 memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
355 memcpy(new_ring + u->ring_size, old_ring,
356 u->ring_size * sizeof(*u->ring));
357
358 u->ring = new_ring;
359 u->ring_size = new_size;
360
361 spin_unlock_irq(&u->ring_prod_lock);
362 mutex_unlock(&u->ring_cons_mutex);
363
364 evtchn_free_ring(old_ring);
365
366 return 0;
367}
368
369static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
370{
371 struct user_evtchn *evtchn;
372 struct evtchn_close close;
373 int rc = 0;
374
375 /*
376 * Ports are never reused, so every caller should pass in a
377 * unique port.
378 *
379 * (Locking not necessary because we haven't registered the
380 * interrupt handler yet, and our caller has already
381 * serialized bind operations.)
382 */
383
384 evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
385 if (!evtchn)
386 return -ENOMEM;
387
388 evtchn->user = u;
389 evtchn->port = port;
390 evtchn->enabled = true; /* start enabled */
391
392 rc = add_evtchn(u, evtchn);
393 if (rc < 0)
394 goto err;
395
396 rc = evtchn_resize_ring(u);
397 if (rc < 0)
398 goto err;
399
400 rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
401 u->name, evtchn);
402 if (rc < 0)
403 goto err;
404
405 rc = evtchn_make_refcounted(port);
406 return rc;
407
408err:
409 /* bind failed, should close the port now */
410 close.port = port;
411 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
412 BUG();
413 del_evtchn(u, evtchn);
414 return rc;
415}
416
417static void evtchn_unbind_from_user(struct per_user_data *u,
418 struct user_evtchn *evtchn)
419{
420 int irq = irq_from_evtchn(evtchn->port);
421
422 BUG_ON(irq < 0);
423
424 unbind_from_irqhandler(irq, evtchn);
425
426 del_evtchn(u, evtchn);
427}
428
429static long evtchn_ioctl(struct file *file,
430 unsigned int cmd, unsigned long arg)
431{
432 int rc;
433 struct per_user_data *u = file->private_data;
434 void __user *uarg = (void __user *) arg;
435
436 /* Prevent bind from racing with unbind */
437 mutex_lock(&u->bind_mutex);
438
439 switch (cmd) {
440 case IOCTL_EVTCHN_BIND_VIRQ: {
441 struct ioctl_evtchn_bind_virq bind;
442 struct evtchn_bind_virq bind_virq;
443
444 rc = -EACCES;
445 if (u->restrict_domid != UNRESTRICTED_DOMID)
446 break;
447
448 rc = -EFAULT;
449 if (copy_from_user(&bind, uarg, sizeof(bind)))
450 break;
451
452 bind_virq.virq = bind.virq;
453 bind_virq.vcpu = xen_vcpu_nr(0);
454 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
455 &bind_virq);
456 if (rc != 0)
457 break;
458
459 rc = evtchn_bind_to_user(u, bind_virq.port);
460 if (rc == 0)
461 rc = bind_virq.port;
462 break;
463 }
464
465 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
466 struct ioctl_evtchn_bind_interdomain bind;
467 struct evtchn_bind_interdomain bind_interdomain;
468
469 rc = -EFAULT;
470 if (copy_from_user(&bind, uarg, sizeof(bind)))
471 break;
472
473 rc = -EACCES;
474 if (u->restrict_domid != UNRESTRICTED_DOMID &&
475 u->restrict_domid != bind.remote_domain)
476 break;
477
478 bind_interdomain.remote_dom = bind.remote_domain;
479 bind_interdomain.remote_port = bind.remote_port;
480 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
481 &bind_interdomain);
482 if (rc != 0)
483 break;
484
485 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
486 if (rc == 0)
487 rc = bind_interdomain.local_port;
488 break;
489 }
490
491 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
492 struct ioctl_evtchn_bind_unbound_port bind;
493 struct evtchn_alloc_unbound alloc_unbound;
494
495 rc = -EACCES;
496 if (u->restrict_domid != UNRESTRICTED_DOMID)
497 break;
498
499 rc = -EFAULT;
500 if (copy_from_user(&bind, uarg, sizeof(bind)))
501 break;
502
503 alloc_unbound.dom = DOMID_SELF;
504 alloc_unbound.remote_dom = bind.remote_domain;
505 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
506 &alloc_unbound);
507 if (rc != 0)
508 break;
509
510 rc = evtchn_bind_to_user(u, alloc_unbound.port);
511 if (rc == 0)
512 rc = alloc_unbound.port;
513 break;
514 }
515
516 case IOCTL_EVTCHN_UNBIND: {
517 struct ioctl_evtchn_unbind unbind;
518 struct user_evtchn *evtchn;
519
520 rc = -EFAULT;
521 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
522 break;
523
524 rc = -EINVAL;
525 if (unbind.port >= xen_evtchn_nr_channels())
526 break;
527
528 rc = -ENOTCONN;
529 evtchn = find_evtchn(u, unbind.port);
530 if (!evtchn)
531 break;
532
533 disable_irq(irq_from_evtchn(unbind.port));
534 evtchn_unbind_from_user(u, evtchn);
535 rc = 0;
536 break;
537 }
538
539 case IOCTL_EVTCHN_NOTIFY: {
540 struct ioctl_evtchn_notify notify;
541 struct user_evtchn *evtchn;
542
543 rc = -EFAULT;
544 if (copy_from_user(¬ify, uarg, sizeof(notify)))
545 break;
546
547 rc = -ENOTCONN;
548 evtchn = find_evtchn(u, notify.port);
549 if (evtchn) {
550 notify_remote_via_evtchn(notify.port);
551 rc = 0;
552 }
553 break;
554 }
555
556 case IOCTL_EVTCHN_RESET: {
557 /* Initialise the ring to empty. Clear errors. */
558 mutex_lock(&u->ring_cons_mutex);
559 spin_lock_irq(&u->ring_prod_lock);
560 WRITE_ONCE(u->ring_cons, 0);
561 WRITE_ONCE(u->ring_prod, 0);
562 u->ring_overflow = 0;
563 spin_unlock_irq(&u->ring_prod_lock);
564 mutex_unlock(&u->ring_cons_mutex);
565 rc = 0;
566 break;
567 }
568
569 case IOCTL_EVTCHN_RESTRICT_DOMID: {
570 struct ioctl_evtchn_restrict_domid ierd;
571
572 rc = -EACCES;
573 if (u->restrict_domid != UNRESTRICTED_DOMID)
574 break;
575
576 rc = -EFAULT;
577 if (copy_from_user(&ierd, uarg, sizeof(ierd)))
578 break;
579
580 rc = -EINVAL;
581 if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED)
582 break;
583
584 u->restrict_domid = ierd.domid;
585 rc = 0;
586
587 break;
588 }
589
590 default:
591 rc = -ENOSYS;
592 break;
593 }
594 mutex_unlock(&u->bind_mutex);
595
596 return rc;
597}
598
599static __poll_t evtchn_poll(struct file *file, poll_table *wait)
600{
601 __poll_t mask = EPOLLOUT | EPOLLWRNORM;
602 struct per_user_data *u = file->private_data;
603
604 poll_wait(file, &u->evtchn_wait, wait);
605 if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))
606 mask |= EPOLLIN | EPOLLRDNORM;
607 if (u->ring_overflow)
608 mask = EPOLLERR;
609 return mask;
610}
611
612static int evtchn_fasync(int fd, struct file *filp, int on)
613{
614 struct per_user_data *u = filp->private_data;
615 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
616}
617
618static int evtchn_open(struct inode *inode, struct file *filp)
619{
620 struct per_user_data *u;
621
622 u = kzalloc(sizeof(*u), GFP_KERNEL);
623 if (u == NULL)
624 return -ENOMEM;
625
626 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
627 if (u->name == NULL) {
628 kfree(u);
629 return -ENOMEM;
630 }
631
632 init_waitqueue_head(&u->evtchn_wait);
633
634 mutex_init(&u->bind_mutex);
635 mutex_init(&u->ring_cons_mutex);
636 spin_lock_init(&u->ring_prod_lock);
637
638 u->restrict_domid = UNRESTRICTED_DOMID;
639
640 filp->private_data = u;
641
642 return stream_open(inode, filp);
643}
644
645static int evtchn_release(struct inode *inode, struct file *filp)
646{
647 struct per_user_data *u = filp->private_data;
648 struct rb_node *node;
649
650 while ((node = u->evtchns.rb_node)) {
651 struct user_evtchn *evtchn;
652
653 evtchn = rb_entry(node, struct user_evtchn, node);
654 disable_irq(irq_from_evtchn(evtchn->port));
655 evtchn_unbind_from_user(u, evtchn);
656 }
657
658 evtchn_free_ring(u->ring);
659 kfree(u->name);
660 kfree(u);
661
662 return 0;
663}
664
665static const struct file_operations evtchn_fops = {
666 .owner = THIS_MODULE,
667 .read = evtchn_read,
668 .write = evtchn_write,
669 .unlocked_ioctl = evtchn_ioctl,
670 .poll = evtchn_poll,
671 .fasync = evtchn_fasync,
672 .open = evtchn_open,
673 .release = evtchn_release,
674 .llseek = no_llseek,
675};
676
677static struct miscdevice evtchn_miscdev = {
678 .minor = MISC_DYNAMIC_MINOR,
679 .name = "xen/evtchn",
680 .fops = &evtchn_fops,
681};
682static int __init evtchn_init(void)
683{
684 int err;
685
686 if (!xen_domain())
687 return -ENODEV;
688
689 /* Create '/dev/xen/evtchn'. */
690 err = misc_register(&evtchn_miscdev);
691 if (err != 0) {
692 pr_err("Could not register /dev/xen/evtchn\n");
693 return err;
694 }
695
696 pr_info("Event-channel device installed\n");
697
698 return 0;
699}
700
701static void __exit evtchn_cleanup(void)
702{
703 misc_deregister(&evtchn_miscdev);
704}
705
706module_init(evtchn_init);
707module_exit(evtchn_cleanup);
708
709MODULE_LICENSE("GPL");
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#include <linux/mm.h>
53#include <linux/vmalloc.h>
54
55#include <xen/xen.h>
56#include <xen/events.h>
57#include <xen/evtchn.h>
58#include <asm/xen/hypervisor.h>
59
60struct per_user_data {
61 struct mutex bind_mutex; /* serialize bind/unbind operations */
62 struct rb_root evtchns;
63 unsigned int nr_evtchns;
64
65 /* Notification ring, accessed via /dev/xen/evtchn. */
66 unsigned int ring_size;
67 evtchn_port_t *ring;
68 unsigned int ring_cons, ring_prod, ring_overflow;
69 struct mutex ring_cons_mutex; /* protect against concurrent readers */
70 spinlock_t ring_prod_lock; /* product against concurrent interrupts */
71
72 /* Processes wait on this queue when ring is empty. */
73 wait_queue_head_t evtchn_wait;
74 struct fasync_struct *evtchn_async_queue;
75 const char *name;
76};
77
78struct user_evtchn {
79 struct rb_node node;
80 struct per_user_data *user;
81 unsigned port;
82 bool enabled;
83};
84
85static evtchn_port_t *evtchn_alloc_ring(unsigned int size)
86{
87 evtchn_port_t *ring;
88 size_t s = size * sizeof(*ring);
89
90 ring = kmalloc(s, GFP_KERNEL);
91 if (!ring)
92 ring = vmalloc(s);
93
94 return ring;
95}
96
97static void evtchn_free_ring(evtchn_port_t *ring)
98{
99 kvfree(ring);
100}
101
102static unsigned int evtchn_ring_offset(struct per_user_data *u,
103 unsigned int idx)
104{
105 return idx & (u->ring_size - 1);
106}
107
108static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
109 unsigned int idx)
110{
111 return u->ring + evtchn_ring_offset(u, idx);
112}
113
114static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
115{
116 struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
117
118 u->nr_evtchns++;
119
120 while (*new) {
121 struct user_evtchn *this;
122
123 this = container_of(*new, struct user_evtchn, node);
124
125 parent = *new;
126 if (this->port < evtchn->port)
127 new = &((*new)->rb_left);
128 else if (this->port > evtchn->port)
129 new = &((*new)->rb_right);
130 else
131 return -EEXIST;
132 }
133
134 /* Add new node and rebalance tree. */
135 rb_link_node(&evtchn->node, parent, new);
136 rb_insert_color(&evtchn->node, &u->evtchns);
137
138 return 0;
139}
140
141static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
142{
143 u->nr_evtchns--;
144 rb_erase(&evtchn->node, &u->evtchns);
145 kfree(evtchn);
146}
147
148static struct user_evtchn *find_evtchn(struct per_user_data *u, unsigned port)
149{
150 struct rb_node *node = u->evtchns.rb_node;
151
152 while (node) {
153 struct user_evtchn *evtchn;
154
155 evtchn = container_of(node, struct user_evtchn, node);
156
157 if (evtchn->port < port)
158 node = node->rb_left;
159 else if (evtchn->port > port)
160 node = node->rb_right;
161 else
162 return evtchn;
163 }
164 return NULL;
165}
166
167static irqreturn_t evtchn_interrupt(int irq, void *data)
168{
169 struct user_evtchn *evtchn = data;
170 struct per_user_data *u = evtchn->user;
171
172 WARN(!evtchn->enabled,
173 "Interrupt for port %d, but apparently not enabled; per-user %p\n",
174 evtchn->port, u);
175
176 disable_irq_nosync(irq);
177 evtchn->enabled = false;
178
179 spin_lock(&u->ring_prod_lock);
180
181 if ((u->ring_prod - u->ring_cons) < u->ring_size) {
182 *evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
183 wmb(); /* Ensure ring contents visible */
184 if (u->ring_cons == u->ring_prod++) {
185 wake_up_interruptible(&u->evtchn_wait);
186 kill_fasync(&u->evtchn_async_queue,
187 SIGIO, POLL_IN);
188 }
189 } else
190 u->ring_overflow = 1;
191
192 spin_unlock(&u->ring_prod_lock);
193
194 return IRQ_HANDLED;
195}
196
197static ssize_t evtchn_read(struct file *file, char __user *buf,
198 size_t count, loff_t *ppos)
199{
200 int rc;
201 unsigned int c, p, bytes1 = 0, bytes2 = 0;
202 struct per_user_data *u = file->private_data;
203
204 /* Whole number of ports. */
205 count &= ~(sizeof(evtchn_port_t)-1);
206
207 if (count == 0)
208 return 0;
209
210 if (count > PAGE_SIZE)
211 count = PAGE_SIZE;
212
213 for (;;) {
214 mutex_lock(&u->ring_cons_mutex);
215
216 rc = -EFBIG;
217 if (u->ring_overflow)
218 goto unlock_out;
219
220 c = u->ring_cons;
221 p = u->ring_prod;
222 if (c != p)
223 break;
224
225 mutex_unlock(&u->ring_cons_mutex);
226
227 if (file->f_flags & O_NONBLOCK)
228 return -EAGAIN;
229
230 rc = wait_event_interruptible(u->evtchn_wait,
231 u->ring_cons != u->ring_prod);
232 if (rc)
233 return rc;
234 }
235
236 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
237 if (((c ^ p) & u->ring_size) != 0) {
238 bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
239 sizeof(evtchn_port_t);
240 bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
241 } else {
242 bytes1 = (p - c) * sizeof(evtchn_port_t);
243 bytes2 = 0;
244 }
245
246 /* Truncate chunks according to caller's maximum byte count. */
247 if (bytes1 > count) {
248 bytes1 = count;
249 bytes2 = 0;
250 } else if ((bytes1 + bytes2) > count) {
251 bytes2 = count - bytes1;
252 }
253
254 rc = -EFAULT;
255 rmb(); /* Ensure that we see the port before we copy it. */
256 if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
257 ((bytes2 != 0) &&
258 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
259 goto unlock_out;
260
261 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
262 rc = bytes1 + bytes2;
263
264 unlock_out:
265 mutex_unlock(&u->ring_cons_mutex);
266 return rc;
267}
268
269static ssize_t evtchn_write(struct file *file, const char __user *buf,
270 size_t count, loff_t *ppos)
271{
272 int rc, i;
273 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
274 struct per_user_data *u = file->private_data;
275
276 if (kbuf == NULL)
277 return -ENOMEM;
278
279 /* Whole number of ports. */
280 count &= ~(sizeof(evtchn_port_t)-1);
281
282 rc = 0;
283 if (count == 0)
284 goto out;
285
286 if (count > PAGE_SIZE)
287 count = PAGE_SIZE;
288
289 rc = -EFAULT;
290 if (copy_from_user(kbuf, buf, count) != 0)
291 goto out;
292
293 mutex_lock(&u->bind_mutex);
294
295 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
296 unsigned port = kbuf[i];
297 struct user_evtchn *evtchn;
298
299 evtchn = find_evtchn(u, port);
300 if (evtchn && !evtchn->enabled) {
301 evtchn->enabled = true;
302 enable_irq(irq_from_evtchn(port));
303 }
304 }
305
306 mutex_unlock(&u->bind_mutex);
307
308 rc = count;
309
310 out:
311 free_page((unsigned long)kbuf);
312 return rc;
313}
314
315static int evtchn_resize_ring(struct per_user_data *u)
316{
317 unsigned int new_size;
318 evtchn_port_t *new_ring, *old_ring;
319
320 /*
321 * Ensure the ring is large enough to capture all possible
322 * events. i.e., one free slot for each bound event.
323 */
324 if (u->nr_evtchns <= u->ring_size)
325 return 0;
326
327 if (u->ring_size == 0)
328 new_size = 64;
329 else
330 new_size = 2 * u->ring_size;
331
332 new_ring = evtchn_alloc_ring(new_size);
333 if (!new_ring)
334 return -ENOMEM;
335
336 old_ring = u->ring;
337
338 /*
339 * Access to the ring contents is serialized by either the
340 * prod /or/ cons lock so take both when resizing.
341 */
342 mutex_lock(&u->ring_cons_mutex);
343 spin_lock_irq(&u->ring_prod_lock);
344
345 /*
346 * Copy the old ring contents to the new ring.
347 *
348 * To take care of wrapping, a full ring, and the new index
349 * pointing into the second half, simply copy the old contents
350 * twice.
351 *
352 * +---------+ +------------------+
353 * |34567 12| -> |34567 1234567 12|
354 * +-----p-c-+ +-------c------p---+
355 */
356 memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
357 memcpy(new_ring + u->ring_size, old_ring,
358 u->ring_size * sizeof(*u->ring));
359
360 u->ring = new_ring;
361 u->ring_size = new_size;
362
363 spin_unlock_irq(&u->ring_prod_lock);
364 mutex_unlock(&u->ring_cons_mutex);
365
366 evtchn_free_ring(old_ring);
367
368 return 0;
369}
370
371static int evtchn_bind_to_user(struct per_user_data *u, int port)
372{
373 struct user_evtchn *evtchn;
374 struct evtchn_close close;
375 int rc = 0;
376
377 /*
378 * Ports are never reused, so every caller should pass in a
379 * unique port.
380 *
381 * (Locking not necessary because we haven't registered the
382 * interrupt handler yet, and our caller has already
383 * serialized bind operations.)
384 */
385
386 evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
387 if (!evtchn)
388 return -ENOMEM;
389
390 evtchn->user = u;
391 evtchn->port = port;
392 evtchn->enabled = true; /* start enabled */
393
394 rc = add_evtchn(u, evtchn);
395 if (rc < 0)
396 goto err;
397
398 rc = evtchn_resize_ring(u);
399 if (rc < 0)
400 goto err;
401
402 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
403 u->name, evtchn);
404 if (rc < 0)
405 goto err;
406
407 rc = evtchn_make_refcounted(port);
408 return rc;
409
410err:
411 /* bind failed, should close the port now */
412 close.port = port;
413 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
414 BUG();
415 del_evtchn(u, evtchn);
416 return rc;
417}
418
419static void evtchn_unbind_from_user(struct per_user_data *u,
420 struct user_evtchn *evtchn)
421{
422 int irq = irq_from_evtchn(evtchn->port);
423
424 BUG_ON(irq < 0);
425
426 unbind_from_irqhandler(irq, evtchn);
427
428 del_evtchn(u, evtchn);
429}
430
431static long evtchn_ioctl(struct file *file,
432 unsigned int cmd, unsigned long arg)
433{
434 int rc;
435 struct per_user_data *u = file->private_data;
436 void __user *uarg = (void __user *) arg;
437
438 /* Prevent bind from racing with unbind */
439 mutex_lock(&u->bind_mutex);
440
441 switch (cmd) {
442 case IOCTL_EVTCHN_BIND_VIRQ: {
443 struct ioctl_evtchn_bind_virq bind;
444 struct evtchn_bind_virq bind_virq;
445
446 rc = -EFAULT;
447 if (copy_from_user(&bind, uarg, sizeof(bind)))
448 break;
449
450 bind_virq.virq = bind.virq;
451 bind_virq.vcpu = 0;
452 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
453 &bind_virq);
454 if (rc != 0)
455 break;
456
457 rc = evtchn_bind_to_user(u, bind_virq.port);
458 if (rc == 0)
459 rc = bind_virq.port;
460 break;
461 }
462
463 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
464 struct ioctl_evtchn_bind_interdomain bind;
465 struct evtchn_bind_interdomain bind_interdomain;
466
467 rc = -EFAULT;
468 if (copy_from_user(&bind, uarg, sizeof(bind)))
469 break;
470
471 bind_interdomain.remote_dom = bind.remote_domain;
472 bind_interdomain.remote_port = bind.remote_port;
473 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
474 &bind_interdomain);
475 if (rc != 0)
476 break;
477
478 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
479 if (rc == 0)
480 rc = bind_interdomain.local_port;
481 break;
482 }
483
484 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
485 struct ioctl_evtchn_bind_unbound_port bind;
486 struct evtchn_alloc_unbound alloc_unbound;
487
488 rc = -EFAULT;
489 if (copy_from_user(&bind, uarg, sizeof(bind)))
490 break;
491
492 alloc_unbound.dom = DOMID_SELF;
493 alloc_unbound.remote_dom = bind.remote_domain;
494 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
495 &alloc_unbound);
496 if (rc != 0)
497 break;
498
499 rc = evtchn_bind_to_user(u, alloc_unbound.port);
500 if (rc == 0)
501 rc = alloc_unbound.port;
502 break;
503 }
504
505 case IOCTL_EVTCHN_UNBIND: {
506 struct ioctl_evtchn_unbind unbind;
507 struct user_evtchn *evtchn;
508
509 rc = -EFAULT;
510 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
511 break;
512
513 rc = -EINVAL;
514 if (unbind.port >= xen_evtchn_nr_channels())
515 break;
516
517 rc = -ENOTCONN;
518 evtchn = find_evtchn(u, unbind.port);
519 if (!evtchn)
520 break;
521
522 disable_irq(irq_from_evtchn(unbind.port));
523 evtchn_unbind_from_user(u, evtchn);
524 rc = 0;
525 break;
526 }
527
528 case IOCTL_EVTCHN_NOTIFY: {
529 struct ioctl_evtchn_notify notify;
530 struct user_evtchn *evtchn;
531
532 rc = -EFAULT;
533 if (copy_from_user(¬ify, uarg, sizeof(notify)))
534 break;
535
536 rc = -ENOTCONN;
537 evtchn = find_evtchn(u, notify.port);
538 if (evtchn) {
539 notify_remote_via_evtchn(notify.port);
540 rc = 0;
541 }
542 break;
543 }
544
545 case IOCTL_EVTCHN_RESET: {
546 /* Initialise the ring to empty. Clear errors. */
547 mutex_lock(&u->ring_cons_mutex);
548 spin_lock_irq(&u->ring_prod_lock);
549 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
550 spin_unlock_irq(&u->ring_prod_lock);
551 mutex_unlock(&u->ring_cons_mutex);
552 rc = 0;
553 break;
554 }
555
556 default:
557 rc = -ENOSYS;
558 break;
559 }
560 mutex_unlock(&u->bind_mutex);
561
562 return rc;
563}
564
565static unsigned int evtchn_poll(struct file *file, poll_table *wait)
566{
567 unsigned int mask = POLLOUT | POLLWRNORM;
568 struct per_user_data *u = file->private_data;
569
570 poll_wait(file, &u->evtchn_wait, wait);
571 if (u->ring_cons != u->ring_prod)
572 mask |= POLLIN | POLLRDNORM;
573 if (u->ring_overflow)
574 mask = POLLERR;
575 return mask;
576}
577
578static int evtchn_fasync(int fd, struct file *filp, int on)
579{
580 struct per_user_data *u = filp->private_data;
581 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
582}
583
584static int evtchn_open(struct inode *inode, struct file *filp)
585{
586 struct per_user_data *u;
587
588 u = kzalloc(sizeof(*u), GFP_KERNEL);
589 if (u == NULL)
590 return -ENOMEM;
591
592 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
593 if (u->name == NULL) {
594 kfree(u);
595 return -ENOMEM;
596 }
597
598 init_waitqueue_head(&u->evtchn_wait);
599
600 mutex_init(&u->bind_mutex);
601 mutex_init(&u->ring_cons_mutex);
602 spin_lock_init(&u->ring_prod_lock);
603
604 filp->private_data = u;
605
606 return nonseekable_open(inode, filp);
607}
608
609static int evtchn_release(struct inode *inode, struct file *filp)
610{
611 struct per_user_data *u = filp->private_data;
612 struct rb_node *node;
613
614 while ((node = u->evtchns.rb_node)) {
615 struct user_evtchn *evtchn;
616
617 evtchn = rb_entry(node, struct user_evtchn, node);
618 disable_irq(irq_from_evtchn(evtchn->port));
619 evtchn_unbind_from_user(u, evtchn);
620 }
621
622 evtchn_free_ring(u->ring);
623 kfree(u->name);
624 kfree(u);
625
626 return 0;
627}
628
629static const struct file_operations evtchn_fops = {
630 .owner = THIS_MODULE,
631 .read = evtchn_read,
632 .write = evtchn_write,
633 .unlocked_ioctl = evtchn_ioctl,
634 .poll = evtchn_poll,
635 .fasync = evtchn_fasync,
636 .open = evtchn_open,
637 .release = evtchn_release,
638 .llseek = no_llseek,
639};
640
641static struct miscdevice evtchn_miscdev = {
642 .minor = MISC_DYNAMIC_MINOR,
643 .name = "xen/evtchn",
644 .fops = &evtchn_fops,
645};
646static int __init evtchn_init(void)
647{
648 int err;
649
650 if (!xen_domain())
651 return -ENODEV;
652
653 /* Create '/dev/xen/evtchn'. */
654 err = misc_register(&evtchn_miscdev);
655 if (err != 0) {
656 pr_err("Could not register /dev/xen/evtchn\n");
657 return err;
658 }
659
660 pr_info("Event-channel device installed\n");
661
662 return 0;
663}
664
665static void __exit evtchn_cleanup(void)
666{
667 misc_deregister(&evtchn_miscdev);
668}
669
670module_init(evtchn_init);
671module_exit(evtchn_cleanup);
672
673MODULE_LICENSE("GPL");