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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
166 WARN(!evtchn->enabled,
167 "Interrupt for port %u, but apparently not enabled; per-user %p\n",
168 evtchn->port, u);
169
170 disable_irq_nosync(irq);
171 evtchn->enabled = false;
172
173 spin_lock(&u->ring_prod_lock);
174
175 if ((u->ring_prod - u->ring_cons) < u->ring_size) {
176 *evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
177 wmb(); /* Ensure ring contents visible */
178 if (u->ring_cons == u->ring_prod++) {
179 wake_up_interruptible(&u->evtchn_wait);
180 kill_fasync(&u->evtchn_async_queue,
181 SIGIO, POLL_IN);
182 }
183 } else
184 u->ring_overflow = 1;
185
186 spin_unlock(&u->ring_prod_lock);
187
188 return IRQ_HANDLED;
189}
190
191static ssize_t evtchn_read(struct file *file, char __user *buf,
192 size_t count, loff_t *ppos)
193{
194 int rc;
195 unsigned int c, p, bytes1 = 0, bytes2 = 0;
196 struct per_user_data *u = file->private_data;
197
198 /* Whole number of ports. */
199 count &= ~(sizeof(evtchn_port_t)-1);
200
201 if (count == 0)
202 return 0;
203
204 if (count > PAGE_SIZE)
205 count = PAGE_SIZE;
206
207 for (;;) {
208 mutex_lock(&u->ring_cons_mutex);
209
210 rc = -EFBIG;
211 if (u->ring_overflow)
212 goto unlock_out;
213
214 c = u->ring_cons;
215 p = u->ring_prod;
216 if (c != p)
217 break;
218
219 mutex_unlock(&u->ring_cons_mutex);
220
221 if (file->f_flags & O_NONBLOCK)
222 return -EAGAIN;
223
224 rc = wait_event_interruptible(u->evtchn_wait,
225 u->ring_cons != u->ring_prod);
226 if (rc)
227 return rc;
228 }
229
230 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
231 if (((c ^ p) & u->ring_size) != 0) {
232 bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
233 sizeof(evtchn_port_t);
234 bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
235 } else {
236 bytes1 = (p - c) * sizeof(evtchn_port_t);
237 bytes2 = 0;
238 }
239
240 /* Truncate chunks according to caller's maximum byte count. */
241 if (bytes1 > count) {
242 bytes1 = count;
243 bytes2 = 0;
244 } else if ((bytes1 + bytes2) > count) {
245 bytes2 = count - bytes1;
246 }
247
248 rc = -EFAULT;
249 rmb(); /* Ensure that we see the port before we copy it. */
250 if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
251 ((bytes2 != 0) &&
252 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
253 goto unlock_out;
254
255 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
256 rc = bytes1 + bytes2;
257
258 unlock_out:
259 mutex_unlock(&u->ring_cons_mutex);
260 return rc;
261}
262
263static ssize_t evtchn_write(struct file *file, const char __user *buf,
264 size_t count, loff_t *ppos)
265{
266 int rc, i;
267 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
268 struct per_user_data *u = file->private_data;
269
270 if (kbuf == NULL)
271 return -ENOMEM;
272
273 /* Whole number of ports. */
274 count &= ~(sizeof(evtchn_port_t)-1);
275
276 rc = 0;
277 if (count == 0)
278 goto out;
279
280 if (count > PAGE_SIZE)
281 count = PAGE_SIZE;
282
283 rc = -EFAULT;
284 if (copy_from_user(kbuf, buf, count) != 0)
285 goto out;
286
287 mutex_lock(&u->bind_mutex);
288
289 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
290 evtchn_port_t port = kbuf[i];
291 struct user_evtchn *evtchn;
292
293 evtchn = find_evtchn(u, port);
294 if (evtchn && !evtchn->enabled) {
295 evtchn->enabled = true;
296 enable_irq(irq_from_evtchn(port));
297 }
298 }
299
300 mutex_unlock(&u->bind_mutex);
301
302 rc = count;
303
304 out:
305 free_page((unsigned long)kbuf);
306 return rc;
307}
308
309static int evtchn_resize_ring(struct per_user_data *u)
310{
311 unsigned int new_size;
312 evtchn_port_t *new_ring, *old_ring;
313
314 /*
315 * Ensure the ring is large enough to capture all possible
316 * events. i.e., one free slot for each bound event.
317 */
318 if (u->nr_evtchns <= u->ring_size)
319 return 0;
320
321 if (u->ring_size == 0)
322 new_size = 64;
323 else
324 new_size = 2 * u->ring_size;
325
326 new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
327 if (!new_ring)
328 return -ENOMEM;
329
330 old_ring = u->ring;
331
332 /*
333 * Access to the ring contents is serialized by either the
334 * prod /or/ cons lock so take both when resizing.
335 */
336 mutex_lock(&u->ring_cons_mutex);
337 spin_lock_irq(&u->ring_prod_lock);
338
339 /*
340 * Copy the old ring contents to the new ring.
341 *
342 * To take care of wrapping, a full ring, and the new index
343 * pointing into the second half, simply copy the old contents
344 * twice.
345 *
346 * +---------+ +------------------+
347 * |34567 12| -> |34567 1234567 12|
348 * +-----p-c-+ +-------c------p---+
349 */
350 memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
351 memcpy(new_ring + u->ring_size, old_ring,
352 u->ring_size * sizeof(*u->ring));
353
354 u->ring = new_ring;
355 u->ring_size = new_size;
356
357 spin_unlock_irq(&u->ring_prod_lock);
358 mutex_unlock(&u->ring_cons_mutex);
359
360 evtchn_free_ring(old_ring);
361
362 return 0;
363}
364
365static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
366{
367 struct user_evtchn *evtchn;
368 struct evtchn_close close;
369 int rc = 0;
370
371 /*
372 * Ports are never reused, so every caller should pass in a
373 * unique port.
374 *
375 * (Locking not necessary because we haven't registered the
376 * interrupt handler yet, and our caller has already
377 * serialized bind operations.)
378 */
379
380 evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
381 if (!evtchn)
382 return -ENOMEM;
383
384 evtchn->user = u;
385 evtchn->port = port;
386 evtchn->enabled = true; /* start enabled */
387
388 rc = add_evtchn(u, evtchn);
389 if (rc < 0)
390 goto err;
391
392 rc = evtchn_resize_ring(u);
393 if (rc < 0)
394 goto err;
395
396 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
397 u->name, evtchn);
398 if (rc < 0)
399 goto err;
400
401 rc = evtchn_make_refcounted(port);
402 return rc;
403
404err:
405 /* bind failed, should close the port now */
406 close.port = port;
407 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
408 BUG();
409 del_evtchn(u, evtchn);
410 return rc;
411}
412
413static void evtchn_unbind_from_user(struct per_user_data *u,
414 struct user_evtchn *evtchn)
415{
416 int irq = irq_from_evtchn(evtchn->port);
417
418 BUG_ON(irq < 0);
419
420 unbind_from_irqhandler(irq, evtchn);
421
422 del_evtchn(u, evtchn);
423}
424
425static DEFINE_PER_CPU(int, bind_last_selected_cpu);
426
427static void evtchn_bind_interdom_next_vcpu(evtchn_port_t evtchn)
428{
429 unsigned int selected_cpu, irq;
430 struct irq_desc *desc;
431 unsigned long flags;
432
433 irq = irq_from_evtchn(evtchn);
434 desc = irq_to_desc(irq);
435
436 if (!desc)
437 return;
438
439 raw_spin_lock_irqsave(&desc->lock, flags);
440 selected_cpu = this_cpu_read(bind_last_selected_cpu);
441 selected_cpu = cpumask_next_and(selected_cpu,
442 desc->irq_common_data.affinity, cpu_online_mask);
443
444 if (unlikely(selected_cpu >= nr_cpu_ids))
445 selected_cpu = cpumask_first_and(desc->irq_common_data.affinity,
446 cpu_online_mask);
447
448 this_cpu_write(bind_last_selected_cpu, selected_cpu);
449
450 /* unmask expects irqs to be disabled */
451 xen_set_affinity_evtchn(desc, selected_cpu);
452 raw_spin_unlock_irqrestore(&desc->lock, flags);
453}
454
455static long evtchn_ioctl(struct file *file,
456 unsigned int cmd, unsigned long arg)
457{
458 int rc;
459 struct per_user_data *u = file->private_data;
460 void __user *uarg = (void __user *) arg;
461
462 /* Prevent bind from racing with unbind */
463 mutex_lock(&u->bind_mutex);
464
465 switch (cmd) {
466 case IOCTL_EVTCHN_BIND_VIRQ: {
467 struct ioctl_evtchn_bind_virq bind;
468 struct evtchn_bind_virq bind_virq;
469
470 rc = -EACCES;
471 if (u->restrict_domid != UNRESTRICTED_DOMID)
472 break;
473
474 rc = -EFAULT;
475 if (copy_from_user(&bind, uarg, sizeof(bind)))
476 break;
477
478 bind_virq.virq = bind.virq;
479 bind_virq.vcpu = xen_vcpu_nr(0);
480 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
481 &bind_virq);
482 if (rc != 0)
483 break;
484
485 rc = evtchn_bind_to_user(u, bind_virq.port);
486 if (rc == 0)
487 rc = bind_virq.port;
488 break;
489 }
490
491 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
492 struct ioctl_evtchn_bind_interdomain bind;
493 struct evtchn_bind_interdomain bind_interdomain;
494
495 rc = -EFAULT;
496 if (copy_from_user(&bind, uarg, sizeof(bind)))
497 break;
498
499 rc = -EACCES;
500 if (u->restrict_domid != UNRESTRICTED_DOMID &&
501 u->restrict_domid != bind.remote_domain)
502 break;
503
504 bind_interdomain.remote_dom = bind.remote_domain;
505 bind_interdomain.remote_port = bind.remote_port;
506 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
507 &bind_interdomain);
508 if (rc != 0)
509 break;
510
511 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
512 if (rc == 0) {
513 rc = bind_interdomain.local_port;
514 evtchn_bind_interdom_next_vcpu(rc);
515 }
516 break;
517 }
518
519 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
520 struct ioctl_evtchn_bind_unbound_port bind;
521 struct evtchn_alloc_unbound alloc_unbound;
522
523 rc = -EACCES;
524 if (u->restrict_domid != UNRESTRICTED_DOMID)
525 break;
526
527 rc = -EFAULT;
528 if (copy_from_user(&bind, uarg, sizeof(bind)))
529 break;
530
531 alloc_unbound.dom = DOMID_SELF;
532 alloc_unbound.remote_dom = bind.remote_domain;
533 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
534 &alloc_unbound);
535 if (rc != 0)
536 break;
537
538 rc = evtchn_bind_to_user(u, alloc_unbound.port);
539 if (rc == 0)
540 rc = alloc_unbound.port;
541 break;
542 }
543
544 case IOCTL_EVTCHN_UNBIND: {
545 struct ioctl_evtchn_unbind unbind;
546 struct user_evtchn *evtchn;
547
548 rc = -EFAULT;
549 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
550 break;
551
552 rc = -EINVAL;
553 if (unbind.port >= xen_evtchn_nr_channels())
554 break;
555
556 rc = -ENOTCONN;
557 evtchn = find_evtchn(u, unbind.port);
558 if (!evtchn)
559 break;
560
561 disable_irq(irq_from_evtchn(unbind.port));
562 evtchn_unbind_from_user(u, evtchn);
563 rc = 0;
564 break;
565 }
566
567 case IOCTL_EVTCHN_NOTIFY: {
568 struct ioctl_evtchn_notify notify;
569 struct user_evtchn *evtchn;
570
571 rc = -EFAULT;
572 if (copy_from_user(¬ify, uarg, sizeof(notify)))
573 break;
574
575 rc = -ENOTCONN;
576 evtchn = find_evtchn(u, notify.port);
577 if (evtchn) {
578 notify_remote_via_evtchn(notify.port);
579 rc = 0;
580 }
581 break;
582 }
583
584 case IOCTL_EVTCHN_RESET: {
585 /* Initialise the ring to empty. Clear errors. */
586 mutex_lock(&u->ring_cons_mutex);
587 spin_lock_irq(&u->ring_prod_lock);
588 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
589 spin_unlock_irq(&u->ring_prod_lock);
590 mutex_unlock(&u->ring_cons_mutex);
591 rc = 0;
592 break;
593 }
594
595 case IOCTL_EVTCHN_RESTRICT_DOMID: {
596 struct ioctl_evtchn_restrict_domid ierd;
597
598 rc = -EACCES;
599 if (u->restrict_domid != UNRESTRICTED_DOMID)
600 break;
601
602 rc = -EFAULT;
603 if (copy_from_user(&ierd, uarg, sizeof(ierd)))
604 break;
605
606 rc = -EINVAL;
607 if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED)
608 break;
609
610 u->restrict_domid = ierd.domid;
611 rc = 0;
612
613 break;
614 }
615
616 default:
617 rc = -ENOSYS;
618 break;
619 }
620 mutex_unlock(&u->bind_mutex);
621
622 return rc;
623}
624
625static __poll_t evtchn_poll(struct file *file, poll_table *wait)
626{
627 __poll_t mask = EPOLLOUT | EPOLLWRNORM;
628 struct per_user_data *u = file->private_data;
629
630 poll_wait(file, &u->evtchn_wait, wait);
631 if (u->ring_cons != u->ring_prod)
632 mask |= EPOLLIN | EPOLLRDNORM;
633 if (u->ring_overflow)
634 mask = EPOLLERR;
635 return mask;
636}
637
638static int evtchn_fasync(int fd, struct file *filp, int on)
639{
640 struct per_user_data *u = filp->private_data;
641 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
642}
643
644static int evtchn_open(struct inode *inode, struct file *filp)
645{
646 struct per_user_data *u;
647
648 u = kzalloc(sizeof(*u), GFP_KERNEL);
649 if (u == NULL)
650 return -ENOMEM;
651
652 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
653 if (u->name == NULL) {
654 kfree(u);
655 return -ENOMEM;
656 }
657
658 init_waitqueue_head(&u->evtchn_wait);
659
660 mutex_init(&u->bind_mutex);
661 mutex_init(&u->ring_cons_mutex);
662 spin_lock_init(&u->ring_prod_lock);
663
664 u->restrict_domid = UNRESTRICTED_DOMID;
665
666 filp->private_data = u;
667
668 return stream_open(inode, filp);
669}
670
671static int evtchn_release(struct inode *inode, struct file *filp)
672{
673 struct per_user_data *u = filp->private_data;
674 struct rb_node *node;
675
676 while ((node = u->evtchns.rb_node)) {
677 struct user_evtchn *evtchn;
678
679 evtchn = rb_entry(node, struct user_evtchn, node);
680 disable_irq(irq_from_evtchn(evtchn->port));
681 evtchn_unbind_from_user(u, evtchn);
682 }
683
684 evtchn_free_ring(u->ring);
685 kfree(u->name);
686 kfree(u);
687
688 return 0;
689}
690
691static const struct file_operations evtchn_fops = {
692 .owner = THIS_MODULE,
693 .read = evtchn_read,
694 .write = evtchn_write,
695 .unlocked_ioctl = evtchn_ioctl,
696 .poll = evtchn_poll,
697 .fasync = evtchn_fasync,
698 .open = evtchn_open,
699 .release = evtchn_release,
700 .llseek = no_llseek,
701};
702
703static struct miscdevice evtchn_miscdev = {
704 .minor = MISC_DYNAMIC_MINOR,
705 .name = "xen/evtchn",
706 .fops = &evtchn_fops,
707};
708static int __init evtchn_init(void)
709{
710 int err;
711
712 if (!xen_domain())
713 return -ENODEV;
714
715 /* Create '/dev/xen/evtchn'. */
716 err = misc_register(&evtchn_miscdev);
717 if (err != 0) {
718 pr_err("Could not register /dev/xen/evtchn\n");
719 return err;
720 }
721
722 pr_info("Event-channel device installed\n");
723
724 return 0;
725}
726
727static void __exit evtchn_cleanup(void)
728{
729 misc_deregister(&evtchn_miscdev);
730}
731
732module_init(evtchn_init);
733module_exit(evtchn_cleanup);
734
735MODULE_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#include <linux/module.h>
35#include <linux/kernel.h>
36#include <linux/sched.h>
37#include <linux/slab.h>
38#include <linux/string.h>
39#include <linux/errno.h>
40#include <linux/fs.h>
41#include <linux/miscdevice.h>
42#include <linux/major.h>
43#include <linux/proc_fs.h>
44#include <linux/stat.h>
45#include <linux/poll.h>
46#include <linux/irq.h>
47#include <linux/init.h>
48#include <linux/mutex.h>
49#include <linux/cpu.h>
50
51#include <xen/xen.h>
52#include <xen/events.h>
53#include <xen/evtchn.h>
54#include <asm/xen/hypervisor.h>
55
56struct per_user_data {
57 struct mutex bind_mutex; /* serialize bind/unbind operations */
58
59 /* Notification ring, accessed via /dev/xen/evtchn. */
60#define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
61#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
62 evtchn_port_t *ring;
63 unsigned int ring_cons, ring_prod, ring_overflow;
64 struct mutex ring_cons_mutex; /* protect against concurrent readers */
65
66 /* Processes wait on this queue when ring is empty. */
67 wait_queue_head_t evtchn_wait;
68 struct fasync_struct *evtchn_async_queue;
69 const char *name;
70};
71
72/*
73 * Who's bound to each port? This is logically an array of struct
74 * per_user_data *, but we encode the current enabled-state in bit 0.
75 */
76static unsigned long *port_user;
77static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
78
79static inline struct per_user_data *get_port_user(unsigned port)
80{
81 return (struct per_user_data *)(port_user[port] & ~1);
82}
83
84static inline void set_port_user(unsigned port, struct per_user_data *u)
85{
86 port_user[port] = (unsigned long)u;
87}
88
89static inline bool get_port_enabled(unsigned port)
90{
91 return port_user[port] & 1;
92}
93
94static inline void set_port_enabled(unsigned port, bool enabled)
95{
96 if (enabled)
97 port_user[port] |= 1;
98 else
99 port_user[port] &= ~1;
100}
101
102static irqreturn_t evtchn_interrupt(int irq, void *data)
103{
104 unsigned int port = (unsigned long)data;
105 struct per_user_data *u;
106
107 spin_lock(&port_user_lock);
108
109 u = get_port_user(port);
110
111 WARN(!get_port_enabled(port),
112 "Interrupt for port %d, but apparently not enabled; per-user %p\n",
113 port, u);
114
115 disable_irq_nosync(irq);
116 set_port_enabled(port, false);
117
118 if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
119 u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port;
120 wmb(); /* Ensure ring contents visible */
121 if (u->ring_cons == u->ring_prod++) {
122 wake_up_interruptible(&u->evtchn_wait);
123 kill_fasync(&u->evtchn_async_queue,
124 SIGIO, POLL_IN);
125 }
126 } else
127 u->ring_overflow = 1;
128
129 spin_unlock(&port_user_lock);
130
131 return IRQ_HANDLED;
132}
133
134static ssize_t evtchn_read(struct file *file, char __user *buf,
135 size_t count, loff_t *ppos)
136{
137 int rc;
138 unsigned int c, p, bytes1 = 0, bytes2 = 0;
139 struct per_user_data *u = file->private_data;
140
141 /* Whole number of ports. */
142 count &= ~(sizeof(evtchn_port_t)-1);
143
144 if (count == 0)
145 return 0;
146
147 if (count > PAGE_SIZE)
148 count = PAGE_SIZE;
149
150 for (;;) {
151 mutex_lock(&u->ring_cons_mutex);
152
153 rc = -EFBIG;
154 if (u->ring_overflow)
155 goto unlock_out;
156
157 c = u->ring_cons;
158 p = u->ring_prod;
159 if (c != p)
160 break;
161
162 mutex_unlock(&u->ring_cons_mutex);
163
164 if (file->f_flags & O_NONBLOCK)
165 return -EAGAIN;
166
167 rc = wait_event_interruptible(u->evtchn_wait,
168 u->ring_cons != u->ring_prod);
169 if (rc)
170 return rc;
171 }
172
173 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
174 if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
175 bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
176 sizeof(evtchn_port_t);
177 bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
178 } else {
179 bytes1 = (p - c) * sizeof(evtchn_port_t);
180 bytes2 = 0;
181 }
182
183 /* Truncate chunks according to caller's maximum byte count. */
184 if (bytes1 > count) {
185 bytes1 = count;
186 bytes2 = 0;
187 } else if ((bytes1 + bytes2) > count) {
188 bytes2 = count - bytes1;
189 }
190
191 rc = -EFAULT;
192 rmb(); /* Ensure that we see the port before we copy it. */
193 if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
194 ((bytes2 != 0) &&
195 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
196 goto unlock_out;
197
198 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
199 rc = bytes1 + bytes2;
200
201 unlock_out:
202 mutex_unlock(&u->ring_cons_mutex);
203 return rc;
204}
205
206static ssize_t evtchn_write(struct file *file, const char __user *buf,
207 size_t count, loff_t *ppos)
208{
209 int rc, i;
210 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
211 struct per_user_data *u = file->private_data;
212
213 if (kbuf == NULL)
214 return -ENOMEM;
215
216 /* Whole number of ports. */
217 count &= ~(sizeof(evtchn_port_t)-1);
218
219 rc = 0;
220 if (count == 0)
221 goto out;
222
223 if (count > PAGE_SIZE)
224 count = PAGE_SIZE;
225
226 rc = -EFAULT;
227 if (copy_from_user(kbuf, buf, count) != 0)
228 goto out;
229
230 spin_lock_irq(&port_user_lock);
231
232 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
233 unsigned port = kbuf[i];
234
235 if (port < NR_EVENT_CHANNELS &&
236 get_port_user(port) == u &&
237 !get_port_enabled(port)) {
238 set_port_enabled(port, true);
239 enable_irq(irq_from_evtchn(port));
240 }
241 }
242
243 spin_unlock_irq(&port_user_lock);
244
245 rc = count;
246
247 out:
248 free_page((unsigned long)kbuf);
249 return rc;
250}
251
252static int evtchn_bind_to_user(struct per_user_data *u, int port)
253{
254 int rc = 0;
255
256 /*
257 * Ports are never reused, so every caller should pass in a
258 * unique port.
259 *
260 * (Locking not necessary because we haven't registered the
261 * interrupt handler yet, and our caller has already
262 * serialized bind operations.)
263 */
264 BUG_ON(get_port_user(port) != NULL);
265 set_port_user(port, u);
266 set_port_enabled(port, true); /* start enabled */
267
268 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
269 u->name, (void *)(unsigned long)port);
270 if (rc >= 0)
271 rc = 0;
272
273 return rc;
274}
275
276static void evtchn_unbind_from_user(struct per_user_data *u, int port)
277{
278 int irq = irq_from_evtchn(port);
279
280 unbind_from_irqhandler(irq, (void *)(unsigned long)port);
281
282 set_port_user(port, NULL);
283}
284
285static long evtchn_ioctl(struct file *file,
286 unsigned int cmd, unsigned long arg)
287{
288 int rc;
289 struct per_user_data *u = file->private_data;
290 void __user *uarg = (void __user *) arg;
291
292 /* Prevent bind from racing with unbind */
293 mutex_lock(&u->bind_mutex);
294
295 switch (cmd) {
296 case IOCTL_EVTCHN_BIND_VIRQ: {
297 struct ioctl_evtchn_bind_virq bind;
298 struct evtchn_bind_virq bind_virq;
299
300 rc = -EFAULT;
301 if (copy_from_user(&bind, uarg, sizeof(bind)))
302 break;
303
304 bind_virq.virq = bind.virq;
305 bind_virq.vcpu = 0;
306 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
307 &bind_virq);
308 if (rc != 0)
309 break;
310
311 rc = evtchn_bind_to_user(u, bind_virq.port);
312 if (rc == 0)
313 rc = bind_virq.port;
314 break;
315 }
316
317 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
318 struct ioctl_evtchn_bind_interdomain bind;
319 struct evtchn_bind_interdomain bind_interdomain;
320
321 rc = -EFAULT;
322 if (copy_from_user(&bind, uarg, sizeof(bind)))
323 break;
324
325 bind_interdomain.remote_dom = bind.remote_domain;
326 bind_interdomain.remote_port = bind.remote_port;
327 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
328 &bind_interdomain);
329 if (rc != 0)
330 break;
331
332 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
333 if (rc == 0)
334 rc = bind_interdomain.local_port;
335 break;
336 }
337
338 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
339 struct ioctl_evtchn_bind_unbound_port bind;
340 struct evtchn_alloc_unbound alloc_unbound;
341
342 rc = -EFAULT;
343 if (copy_from_user(&bind, uarg, sizeof(bind)))
344 break;
345
346 alloc_unbound.dom = DOMID_SELF;
347 alloc_unbound.remote_dom = bind.remote_domain;
348 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
349 &alloc_unbound);
350 if (rc != 0)
351 break;
352
353 rc = evtchn_bind_to_user(u, alloc_unbound.port);
354 if (rc == 0)
355 rc = alloc_unbound.port;
356 break;
357 }
358
359 case IOCTL_EVTCHN_UNBIND: {
360 struct ioctl_evtchn_unbind unbind;
361
362 rc = -EFAULT;
363 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
364 break;
365
366 rc = -EINVAL;
367 if (unbind.port >= NR_EVENT_CHANNELS)
368 break;
369
370 spin_lock_irq(&port_user_lock);
371
372 rc = -ENOTCONN;
373 if (get_port_user(unbind.port) != u) {
374 spin_unlock_irq(&port_user_lock);
375 break;
376 }
377
378 disable_irq(irq_from_evtchn(unbind.port));
379
380 spin_unlock_irq(&port_user_lock);
381
382 evtchn_unbind_from_user(u, unbind.port);
383
384 rc = 0;
385 break;
386 }
387
388 case IOCTL_EVTCHN_NOTIFY: {
389 struct ioctl_evtchn_notify notify;
390
391 rc = -EFAULT;
392 if (copy_from_user(¬ify, uarg, sizeof(notify)))
393 break;
394
395 if (notify.port >= NR_EVENT_CHANNELS) {
396 rc = -EINVAL;
397 } else if (get_port_user(notify.port) != u) {
398 rc = -ENOTCONN;
399 } else {
400 notify_remote_via_evtchn(notify.port);
401 rc = 0;
402 }
403 break;
404 }
405
406 case IOCTL_EVTCHN_RESET: {
407 /* Initialise the ring to empty. Clear errors. */
408 mutex_lock(&u->ring_cons_mutex);
409 spin_lock_irq(&port_user_lock);
410 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
411 spin_unlock_irq(&port_user_lock);
412 mutex_unlock(&u->ring_cons_mutex);
413 rc = 0;
414 break;
415 }
416
417 default:
418 rc = -ENOSYS;
419 break;
420 }
421 mutex_unlock(&u->bind_mutex);
422
423 return rc;
424}
425
426static unsigned int evtchn_poll(struct file *file, poll_table *wait)
427{
428 unsigned int mask = POLLOUT | POLLWRNORM;
429 struct per_user_data *u = file->private_data;
430
431 poll_wait(file, &u->evtchn_wait, wait);
432 if (u->ring_cons != u->ring_prod)
433 mask |= POLLIN | POLLRDNORM;
434 if (u->ring_overflow)
435 mask = POLLERR;
436 return mask;
437}
438
439static int evtchn_fasync(int fd, struct file *filp, int on)
440{
441 struct per_user_data *u = filp->private_data;
442 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
443}
444
445static int evtchn_open(struct inode *inode, struct file *filp)
446{
447 struct per_user_data *u;
448
449 u = kzalloc(sizeof(*u), GFP_KERNEL);
450 if (u == NULL)
451 return -ENOMEM;
452
453 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
454 if (u->name == NULL) {
455 kfree(u);
456 return -ENOMEM;
457 }
458
459 init_waitqueue_head(&u->evtchn_wait);
460
461 u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
462 if (u->ring == NULL) {
463 kfree(u->name);
464 kfree(u);
465 return -ENOMEM;
466 }
467
468 mutex_init(&u->bind_mutex);
469 mutex_init(&u->ring_cons_mutex);
470
471 filp->private_data = u;
472
473 return nonseekable_open(inode, filp);
474}
475
476static int evtchn_release(struct inode *inode, struct file *filp)
477{
478 int i;
479 struct per_user_data *u = filp->private_data;
480
481 spin_lock_irq(&port_user_lock);
482
483 free_page((unsigned long)u->ring);
484
485 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
486 if (get_port_user(i) != u)
487 continue;
488
489 disable_irq(irq_from_evtchn(i));
490 }
491
492 spin_unlock_irq(&port_user_lock);
493
494 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
495 if (get_port_user(i) != u)
496 continue;
497
498 evtchn_unbind_from_user(get_port_user(i), i);
499 }
500
501 kfree(u->name);
502 kfree(u);
503
504 return 0;
505}
506
507static const struct file_operations evtchn_fops = {
508 .owner = THIS_MODULE,
509 .read = evtchn_read,
510 .write = evtchn_write,
511 .unlocked_ioctl = evtchn_ioctl,
512 .poll = evtchn_poll,
513 .fasync = evtchn_fasync,
514 .open = evtchn_open,
515 .release = evtchn_release,
516 .llseek = no_llseek,
517};
518
519static struct miscdevice evtchn_miscdev = {
520 .minor = MISC_DYNAMIC_MINOR,
521 .name = "xen/evtchn",
522 .fops = &evtchn_fops,
523};
524static int __init evtchn_init(void)
525{
526 int err;
527
528 if (!xen_domain())
529 return -ENODEV;
530
531 port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL);
532 if (port_user == NULL)
533 return -ENOMEM;
534
535 spin_lock_init(&port_user_lock);
536
537 /* Create '/dev/misc/evtchn'. */
538 err = misc_register(&evtchn_miscdev);
539 if (err != 0) {
540 printk(KERN_ALERT "Could not register /dev/misc/evtchn\n");
541 return err;
542 }
543
544 printk(KERN_INFO "Event-channel device installed.\n");
545
546 return 0;
547}
548
549static void __exit evtchn_cleanup(void)
550{
551 kfree(port_user);
552 port_user = NULL;
553
554 misc_deregister(&evtchn_miscdev);
555}
556
557module_init(evtchn_init);
558module_exit(evtchn_cleanup);
559
560MODULE_LICENSE("GPL");