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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 bool unbinding;
89};
90
91static void evtchn_free_ring(evtchn_port_t *ring)
92{
93 kvfree(ring);
94}
95
96static unsigned int evtchn_ring_offset(struct per_user_data *u,
97 unsigned int idx)
98{
99 return idx & (u->ring_size - 1);
100}
101
102static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
103 unsigned int idx)
104{
105 return u->ring + evtchn_ring_offset(u, idx);
106}
107
108static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
109{
110 struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
111
112 u->nr_evtchns++;
113
114 while (*new) {
115 struct user_evtchn *this;
116
117 this = rb_entry(*new, struct user_evtchn, node);
118
119 parent = *new;
120 if (this->port < evtchn->port)
121 new = &((*new)->rb_left);
122 else if (this->port > evtchn->port)
123 new = &((*new)->rb_right);
124 else
125 return -EEXIST;
126 }
127
128 /* Add new node and rebalance tree. */
129 rb_link_node(&evtchn->node, parent, new);
130 rb_insert_color(&evtchn->node, &u->evtchns);
131
132 return 0;
133}
134
135static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
136{
137 u->nr_evtchns--;
138 rb_erase(&evtchn->node, &u->evtchns);
139 kfree(evtchn);
140}
141
142static struct user_evtchn *find_evtchn(struct per_user_data *u,
143 evtchn_port_t port)
144{
145 struct rb_node *node = u->evtchns.rb_node;
146
147 while (node) {
148 struct user_evtchn *evtchn;
149
150 evtchn = rb_entry(node, struct user_evtchn, node);
151
152 if (evtchn->port < port)
153 node = node->rb_left;
154 else if (evtchn->port > port)
155 node = node->rb_right;
156 else
157 return evtchn;
158 }
159 return NULL;
160}
161
162static irqreturn_t evtchn_interrupt(int irq, void *data)
163{
164 struct user_evtchn *evtchn = data;
165 struct per_user_data *u = evtchn->user;
166 unsigned int prod, cons;
167
168 /* Handler might be called when tearing down the IRQ. */
169 if (evtchn->unbinding)
170 return IRQ_HANDLED;
171
172 WARN(!evtchn->enabled,
173 "Interrupt for port %u, but apparently not enabled; per-user %p\n",
174 evtchn->port, u);
175
176 evtchn->enabled = false;
177
178 spin_lock(&u->ring_prod_lock);
179
180 prod = READ_ONCE(u->ring_prod);
181 cons = READ_ONCE(u->ring_cons);
182
183 if ((prod - cons) < u->ring_size) {
184 *evtchn_ring_entry(u, prod) = evtchn->port;
185 smp_wmb(); /* Ensure ring contents visible */
186 WRITE_ONCE(u->ring_prod, prod + 1);
187 if (cons == prod) {
188 wake_up_interruptible(&u->evtchn_wait);
189 kill_fasync(&u->evtchn_async_queue,
190 SIGIO, POLL_IN);
191 }
192 } else
193 u->ring_overflow = 1;
194
195 spin_unlock(&u->ring_prod_lock);
196
197 return IRQ_HANDLED;
198}
199
200static ssize_t evtchn_read(struct file *file, char __user *buf,
201 size_t count, loff_t *ppos)
202{
203 int rc;
204 unsigned int c, p, bytes1 = 0, bytes2 = 0;
205 struct per_user_data *u = file->private_data;
206
207 /* Whole number of ports. */
208 count &= ~(sizeof(evtchn_port_t)-1);
209
210 if (count == 0)
211 return 0;
212
213 if (count > PAGE_SIZE)
214 count = PAGE_SIZE;
215
216 for (;;) {
217 mutex_lock(&u->ring_cons_mutex);
218
219 rc = -EFBIG;
220 if (u->ring_overflow)
221 goto unlock_out;
222
223 c = READ_ONCE(u->ring_cons);
224 p = READ_ONCE(u->ring_prod);
225 if (c != p)
226 break;
227
228 mutex_unlock(&u->ring_cons_mutex);
229
230 if (file->f_flags & O_NONBLOCK)
231 return -EAGAIN;
232
233 rc = wait_event_interruptible(u->evtchn_wait,
234 READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));
235 if (rc)
236 return rc;
237 }
238
239 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
240 if (((c ^ p) & u->ring_size) != 0) {
241 bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
242 sizeof(evtchn_port_t);
243 bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
244 } else {
245 bytes1 = (p - c) * sizeof(evtchn_port_t);
246 bytes2 = 0;
247 }
248
249 /* Truncate chunks according to caller's maximum byte count. */
250 if (bytes1 > count) {
251 bytes1 = count;
252 bytes2 = 0;
253 } else if ((bytes1 + bytes2) > count) {
254 bytes2 = count - bytes1;
255 }
256
257 rc = -EFAULT;
258 smp_rmb(); /* Ensure that we see the port before we copy it. */
259 if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
260 ((bytes2 != 0) &&
261 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
262 goto unlock_out;
263
264 WRITE_ONCE(u->ring_cons, c + (bytes1 + bytes2) / sizeof(evtchn_port_t));
265 rc = bytes1 + bytes2;
266
267 unlock_out:
268 mutex_unlock(&u->ring_cons_mutex);
269 return rc;
270}
271
272static ssize_t evtchn_write(struct file *file, const char __user *buf,
273 size_t count, loff_t *ppos)
274{
275 int rc, i;
276 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
277 struct per_user_data *u = file->private_data;
278
279 if (kbuf == NULL)
280 return -ENOMEM;
281
282 /* Whole number of ports. */
283 count &= ~(sizeof(evtchn_port_t)-1);
284
285 rc = 0;
286 if (count == 0)
287 goto out;
288
289 if (count > PAGE_SIZE)
290 count = PAGE_SIZE;
291
292 rc = -EFAULT;
293 if (copy_from_user(kbuf, buf, count) != 0)
294 goto out;
295
296 mutex_lock(&u->bind_mutex);
297
298 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
299 evtchn_port_t port = kbuf[i];
300 struct user_evtchn *evtchn;
301
302 evtchn = find_evtchn(u, port);
303 if (evtchn && !evtchn->enabled) {
304 evtchn->enabled = true;
305 xen_irq_lateeoi(irq_from_evtchn(port), 0);
306 }
307 }
308
309 mutex_unlock(&u->bind_mutex);
310
311 rc = count;
312
313 out:
314 free_page((unsigned long)kbuf);
315 return rc;
316}
317
318static int evtchn_resize_ring(struct per_user_data *u)
319{
320 unsigned int new_size;
321 evtchn_port_t *new_ring, *old_ring;
322
323 /*
324 * Ensure the ring is large enough to capture all possible
325 * events. i.e., one free slot for each bound event.
326 */
327 if (u->nr_evtchns <= u->ring_size)
328 return 0;
329
330 if (u->ring_size == 0)
331 new_size = 64;
332 else
333 new_size = 2 * u->ring_size;
334
335 new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
336 if (!new_ring)
337 return -ENOMEM;
338
339 old_ring = u->ring;
340
341 /*
342 * Access to the ring contents is serialized by either the
343 * prod /or/ cons lock so take both when resizing.
344 */
345 mutex_lock(&u->ring_cons_mutex);
346 spin_lock_irq(&u->ring_prod_lock);
347
348 /*
349 * Copy the old ring contents to the new ring.
350 *
351 * To take care of wrapping, a full ring, and the new index
352 * pointing into the second half, simply copy the old contents
353 * twice.
354 *
355 * +---------+ +------------------+
356 * |34567 12| -> |34567 1234567 12|
357 * +-----p-c-+ +-------c------p---+
358 */
359 memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
360 memcpy(new_ring + u->ring_size, old_ring,
361 u->ring_size * sizeof(*u->ring));
362
363 u->ring = new_ring;
364 u->ring_size = new_size;
365
366 spin_unlock_irq(&u->ring_prod_lock);
367 mutex_unlock(&u->ring_cons_mutex);
368
369 evtchn_free_ring(old_ring);
370
371 return 0;
372}
373
374static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port,
375 bool is_static)
376{
377 struct user_evtchn *evtchn;
378 int rc = 0;
379
380 /*
381 * Ports are never reused, so every caller should pass in a
382 * unique port.
383 *
384 * (Locking not necessary because we haven't registered the
385 * interrupt handler yet, and our caller has already
386 * serialized bind operations.)
387 */
388
389 evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
390 if (!evtchn)
391 return -ENOMEM;
392
393 evtchn->user = u;
394 evtchn->port = port;
395 evtchn->enabled = true; /* start enabled */
396
397 rc = add_evtchn(u, evtchn);
398 if (rc < 0)
399 goto err;
400
401 rc = evtchn_resize_ring(u);
402 if (rc < 0)
403 goto err;
404
405 rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, IRQF_SHARED,
406 u->name, evtchn);
407 if (rc < 0)
408 goto err;
409
410 rc = evtchn_make_refcounted(port, is_static);
411 return rc;
412
413err:
414 /* bind failed, should close the port now */
415 if (!is_static)
416 xen_evtchn_close(port);
417
418 del_evtchn(u, evtchn);
419 return rc;
420}
421
422static void evtchn_unbind_from_user(struct per_user_data *u,
423 struct user_evtchn *evtchn)
424{
425 int irq = irq_from_evtchn(evtchn->port);
426
427 BUG_ON(irq < 0);
428
429 evtchn->unbinding = true;
430 unbind_from_irqhandler(irq, evtchn);
431
432 del_evtchn(u, evtchn);
433}
434
435static long evtchn_ioctl(struct file *file,
436 unsigned int cmd, unsigned long arg)
437{
438 int rc;
439 struct per_user_data *u = file->private_data;
440 void __user *uarg = (void __user *) arg;
441
442 /* Prevent bind from racing with unbind */
443 mutex_lock(&u->bind_mutex);
444
445 switch (cmd) {
446 case IOCTL_EVTCHN_BIND_VIRQ: {
447 struct ioctl_evtchn_bind_virq bind;
448 struct evtchn_bind_virq bind_virq;
449
450 rc = -EACCES;
451 if (u->restrict_domid != UNRESTRICTED_DOMID)
452 break;
453
454 rc = -EFAULT;
455 if (copy_from_user(&bind, uarg, sizeof(bind)))
456 break;
457
458 bind_virq.virq = bind.virq;
459 bind_virq.vcpu = xen_vcpu_nr(0);
460 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
461 &bind_virq);
462 if (rc != 0)
463 break;
464
465 rc = evtchn_bind_to_user(u, bind_virq.port, false);
466 if (rc == 0)
467 rc = bind_virq.port;
468 break;
469 }
470
471 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
472 struct ioctl_evtchn_bind_interdomain bind;
473 struct evtchn_bind_interdomain bind_interdomain;
474
475 rc = -EFAULT;
476 if (copy_from_user(&bind, uarg, sizeof(bind)))
477 break;
478
479 rc = -EACCES;
480 if (u->restrict_domid != UNRESTRICTED_DOMID &&
481 u->restrict_domid != bind.remote_domain)
482 break;
483
484 bind_interdomain.remote_dom = bind.remote_domain;
485 bind_interdomain.remote_port = bind.remote_port;
486 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
487 &bind_interdomain);
488 if (rc != 0)
489 break;
490
491 rc = evtchn_bind_to_user(u, bind_interdomain.local_port, false);
492 if (rc == 0)
493 rc = bind_interdomain.local_port;
494 break;
495 }
496
497 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
498 struct ioctl_evtchn_bind_unbound_port bind;
499 struct evtchn_alloc_unbound alloc_unbound;
500
501 rc = -EACCES;
502 if (u->restrict_domid != UNRESTRICTED_DOMID)
503 break;
504
505 rc = -EFAULT;
506 if (copy_from_user(&bind, uarg, sizeof(bind)))
507 break;
508
509 alloc_unbound.dom = DOMID_SELF;
510 alloc_unbound.remote_dom = bind.remote_domain;
511 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
512 &alloc_unbound);
513 if (rc != 0)
514 break;
515
516 rc = evtchn_bind_to_user(u, alloc_unbound.port, false);
517 if (rc == 0)
518 rc = alloc_unbound.port;
519 break;
520 }
521
522 case IOCTL_EVTCHN_UNBIND: {
523 struct ioctl_evtchn_unbind unbind;
524 struct user_evtchn *evtchn;
525
526 rc = -EFAULT;
527 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
528 break;
529
530 rc = -EINVAL;
531 if (unbind.port >= xen_evtchn_nr_channels())
532 break;
533
534 rc = -ENOTCONN;
535 evtchn = find_evtchn(u, unbind.port);
536 if (!evtchn)
537 break;
538
539 disable_irq(irq_from_evtchn(unbind.port));
540 evtchn_unbind_from_user(u, evtchn);
541 rc = 0;
542 break;
543 }
544
545 case IOCTL_EVTCHN_BIND_STATIC: {
546 struct ioctl_evtchn_bind bind;
547 struct user_evtchn *evtchn;
548
549 rc = -EFAULT;
550 if (copy_from_user(&bind, uarg, sizeof(bind)))
551 break;
552
553 rc = -EISCONN;
554 evtchn = find_evtchn(u, bind.port);
555 if (evtchn)
556 break;
557
558 rc = evtchn_bind_to_user(u, bind.port, true);
559 break;
560 }
561
562 case IOCTL_EVTCHN_NOTIFY: {
563 struct ioctl_evtchn_notify notify;
564 struct user_evtchn *evtchn;
565
566 rc = -EFAULT;
567 if (copy_from_user(¬ify, uarg, sizeof(notify)))
568 break;
569
570 rc = -ENOTCONN;
571 evtchn = find_evtchn(u, notify.port);
572 if (evtchn) {
573 notify_remote_via_evtchn(notify.port);
574 rc = 0;
575 }
576 break;
577 }
578
579 case IOCTL_EVTCHN_RESET: {
580 /* Initialise the ring to empty. Clear errors. */
581 mutex_lock(&u->ring_cons_mutex);
582 spin_lock_irq(&u->ring_prod_lock);
583 WRITE_ONCE(u->ring_cons, 0);
584 WRITE_ONCE(u->ring_prod, 0);
585 u->ring_overflow = 0;
586 spin_unlock_irq(&u->ring_prod_lock);
587 mutex_unlock(&u->ring_cons_mutex);
588 rc = 0;
589 break;
590 }
591
592 case IOCTL_EVTCHN_RESTRICT_DOMID: {
593 struct ioctl_evtchn_restrict_domid ierd;
594
595 rc = -EACCES;
596 if (u->restrict_domid != UNRESTRICTED_DOMID)
597 break;
598
599 rc = -EFAULT;
600 if (copy_from_user(&ierd, uarg, sizeof(ierd)))
601 break;
602
603 rc = -EINVAL;
604 if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED)
605 break;
606
607 u->restrict_domid = ierd.domid;
608 rc = 0;
609
610 break;
611 }
612
613 default:
614 rc = -ENOSYS;
615 break;
616 }
617 mutex_unlock(&u->bind_mutex);
618
619 return rc;
620}
621
622static __poll_t evtchn_poll(struct file *file, poll_table *wait)
623{
624 __poll_t mask = EPOLLOUT | EPOLLWRNORM;
625 struct per_user_data *u = file->private_data;
626
627 poll_wait(file, &u->evtchn_wait, wait);
628 if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))
629 mask |= EPOLLIN | EPOLLRDNORM;
630 if (u->ring_overflow)
631 mask = EPOLLERR;
632 return mask;
633}
634
635static int evtchn_fasync(int fd, struct file *filp, int on)
636{
637 struct per_user_data *u = filp->private_data;
638 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
639}
640
641static int evtchn_open(struct inode *inode, struct file *filp)
642{
643 struct per_user_data *u;
644
645 u = kzalloc(sizeof(*u), GFP_KERNEL);
646 if (u == NULL)
647 return -ENOMEM;
648
649 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
650 if (u->name == NULL) {
651 kfree(u);
652 return -ENOMEM;
653 }
654
655 init_waitqueue_head(&u->evtchn_wait);
656
657 mutex_init(&u->bind_mutex);
658 mutex_init(&u->ring_cons_mutex);
659 spin_lock_init(&u->ring_prod_lock);
660
661 u->restrict_domid = UNRESTRICTED_DOMID;
662
663 filp->private_data = u;
664
665 return stream_open(inode, filp);
666}
667
668static int evtchn_release(struct inode *inode, struct file *filp)
669{
670 struct per_user_data *u = filp->private_data;
671 struct rb_node *node;
672
673 while ((node = u->evtchns.rb_node)) {
674 struct user_evtchn *evtchn;
675
676 evtchn = rb_entry(node, struct user_evtchn, node);
677 disable_irq(irq_from_evtchn(evtchn->port));
678 evtchn_unbind_from_user(u, evtchn);
679 }
680
681 evtchn_free_ring(u->ring);
682 kfree(u->name);
683 kfree(u);
684
685 return 0;
686}
687
688static const struct file_operations evtchn_fops = {
689 .owner = THIS_MODULE,
690 .read = evtchn_read,
691 .write = evtchn_write,
692 .unlocked_ioctl = evtchn_ioctl,
693 .poll = evtchn_poll,
694 .fasync = evtchn_fasync,
695 .open = evtchn_open,
696 .release = evtchn_release,
697};
698
699static struct miscdevice evtchn_miscdev = {
700 .minor = MISC_DYNAMIC_MINOR,
701 .name = "xen/evtchn",
702 .fops = &evtchn_fops,
703};
704static int __init evtchn_init(void)
705{
706 int err;
707
708 if (!xen_domain())
709 return -ENODEV;
710
711 /* Create '/dev/xen/evtchn'. */
712 err = misc_register(&evtchn_miscdev);
713 if (err != 0) {
714 pr_err("Could not register /dev/xen/evtchn\n");
715 return err;
716 }
717
718 pr_info("Event-channel device installed\n");
719
720 return 0;
721}
722
723static void __exit evtchn_cleanup(void)
724{
725 misc_deregister(&evtchn_miscdev);
726}
727
728module_init(evtchn_init);
729module_exit(evtchn_cleanup);
730
731MODULE_DESCRIPTION("Xen /dev/xen/evtchn device driver");
732MODULE_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 <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");