1 /******************************************************************************
4 * Driver for receiving and demuxing event-channel signals.
6 * Copyright (c) 2004-2005, K A Fraser
7 * Multi-process extensions Copyright (c) 2004, Steven Smith
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:
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:
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
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
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>
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>
52 #include <xen/events.h>
53 #include <xen/evtchn.h>
54 #include <asm/xen/hypervisor.h>
56 struct per_user_data {
57 struct mutex bind_mutex; /* serialize bind/unbind operations */
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))
63 unsigned int ring_cons, ring_prod, ring_overflow;
64 struct mutex ring_cons_mutex; /* protect against concurrent readers */
66 /* Processes wait on this queue when ring is empty. */
67 wait_queue_head_t evtchn_wait;
68 struct fasync_struct *evtchn_async_queue;
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.
76 static unsigned long *port_user;
77 static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
79 static inline struct per_user_data *get_port_user(unsigned port)
81 return (struct per_user_data *)(port_user[port] & ~1);
84 static inline void set_port_user(unsigned port, struct per_user_data *u)
86 port_user[port] = (unsigned long)u;
89 static inline bool get_port_enabled(unsigned port)
91 return port_user[port] & 1;
94 static inline void set_port_enabled(unsigned port, bool enabled)
99 port_user[port] &= ~1;
102 static irqreturn_t evtchn_interrupt(int irq, void *data)
104 unsigned int port = (unsigned long)data;
105 struct per_user_data *u;
107 spin_lock(&port_user_lock);
109 u = get_port_user(port);
111 WARN(!get_port_enabled(port),
112 "Interrupt for port %d, but apparently not enabled; per-user %p\n",
115 disable_irq_nosync(irq);
116 set_port_enabled(port, false);
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,
127 u->ring_overflow = 1;
129 spin_unlock(&port_user_lock);
134 static ssize_t evtchn_read(struct file *file, char __user *buf,
135 size_t count, loff_t *ppos)
138 unsigned int c, p, bytes1 = 0, bytes2 = 0;
139 struct per_user_data *u = file->private_data;
141 /* Whole number of ports. */
142 count &= ~(sizeof(evtchn_port_t)-1);
147 if (count > PAGE_SIZE)
151 mutex_lock(&u->ring_cons_mutex);
154 if (u->ring_overflow)
162 mutex_unlock(&u->ring_cons_mutex);
164 if (file->f_flags & O_NONBLOCK)
167 rc = wait_event_interruptible(u->evtchn_wait,
168 u->ring_cons != u->ring_prod);
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);
179 bytes1 = (p - c) * sizeof(evtchn_port_t);
183 /* Truncate chunks according to caller's maximum byte count. */
184 if (bytes1 > count) {
187 } else if ((bytes1 + bytes2) > count) {
188 bytes2 = count - bytes1;
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) ||
195 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
198 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
199 rc = bytes1 + bytes2;
202 mutex_unlock(&u->ring_cons_mutex);
206 static ssize_t evtchn_write(struct file *file, const char __user *buf,
207 size_t count, loff_t *ppos)
210 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
211 struct per_user_data *u = file->private_data;
216 /* Whole number of ports. */
217 count &= ~(sizeof(evtchn_port_t)-1);
223 if (count > PAGE_SIZE)
227 if (copy_from_user(kbuf, buf, count) != 0)
230 spin_lock_irq(&port_user_lock);
232 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
233 unsigned port = kbuf[i];
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));
243 spin_unlock_irq(&port_user_lock);
248 free_page((unsigned long)kbuf);
252 static int evtchn_bind_to_user(struct per_user_data *u, int port)
257 * Ports are never reused, so every caller should pass in a
260 * (Locking not necessary because we haven't registered the
261 * interrupt handler yet, and our caller has already
262 * serialized bind operations.)
264 BUG_ON(get_port_user(port) != NULL);
265 set_port_user(port, u);
266 set_port_enabled(port, true); /* start enabled */
268 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
269 u->name, (void *)(unsigned long)port);
271 rc = evtchn_make_refcounted(port);
273 /* bind failed, should close the port now */
274 struct evtchn_close close;
276 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
278 set_port_user(port, NULL);
284 static void evtchn_unbind_from_user(struct per_user_data *u, int port)
286 int irq = irq_from_evtchn(port);
290 unbind_from_irqhandler(irq, (void *)(unsigned long)port);
292 set_port_user(port, NULL);
295 static long evtchn_ioctl(struct file *file,
296 unsigned int cmd, unsigned long arg)
299 struct per_user_data *u = file->private_data;
300 void __user *uarg = (void __user *) arg;
302 /* Prevent bind from racing with unbind */
303 mutex_lock(&u->bind_mutex);
306 case IOCTL_EVTCHN_BIND_VIRQ: {
307 struct ioctl_evtchn_bind_virq bind;
308 struct evtchn_bind_virq bind_virq;
311 if (copy_from_user(&bind, uarg, sizeof(bind)))
314 bind_virq.virq = bind.virq;
316 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
321 rc = evtchn_bind_to_user(u, bind_virq.port);
327 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
328 struct ioctl_evtchn_bind_interdomain bind;
329 struct evtchn_bind_interdomain bind_interdomain;
332 if (copy_from_user(&bind, uarg, sizeof(bind)))
335 bind_interdomain.remote_dom = bind.remote_domain;
336 bind_interdomain.remote_port = bind.remote_port;
337 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
342 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
344 rc = bind_interdomain.local_port;
348 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
349 struct ioctl_evtchn_bind_unbound_port bind;
350 struct evtchn_alloc_unbound alloc_unbound;
353 if (copy_from_user(&bind, uarg, sizeof(bind)))
356 alloc_unbound.dom = DOMID_SELF;
357 alloc_unbound.remote_dom = bind.remote_domain;
358 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
363 rc = evtchn_bind_to_user(u, alloc_unbound.port);
365 rc = alloc_unbound.port;
369 case IOCTL_EVTCHN_UNBIND: {
370 struct ioctl_evtchn_unbind unbind;
373 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
377 if (unbind.port >= NR_EVENT_CHANNELS)
380 spin_lock_irq(&port_user_lock);
383 if (get_port_user(unbind.port) != u) {
384 spin_unlock_irq(&port_user_lock);
388 disable_irq(irq_from_evtchn(unbind.port));
390 spin_unlock_irq(&port_user_lock);
392 evtchn_unbind_from_user(u, unbind.port);
398 case IOCTL_EVTCHN_NOTIFY: {
399 struct ioctl_evtchn_notify notify;
402 if (copy_from_user(¬ify, uarg, sizeof(notify)))
405 if (notify.port >= NR_EVENT_CHANNELS) {
407 } else if (get_port_user(notify.port) != u) {
410 notify_remote_via_evtchn(notify.port);
416 case IOCTL_EVTCHN_RESET: {
417 /* Initialise the ring to empty. Clear errors. */
418 mutex_lock(&u->ring_cons_mutex);
419 spin_lock_irq(&port_user_lock);
420 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
421 spin_unlock_irq(&port_user_lock);
422 mutex_unlock(&u->ring_cons_mutex);
431 mutex_unlock(&u->bind_mutex);
436 static unsigned int evtchn_poll(struct file *file, poll_table *wait)
438 unsigned int mask = POLLOUT | POLLWRNORM;
439 struct per_user_data *u = file->private_data;
441 poll_wait(file, &u->evtchn_wait, wait);
442 if (u->ring_cons != u->ring_prod)
443 mask |= POLLIN | POLLRDNORM;
444 if (u->ring_overflow)
449 static int evtchn_fasync(int fd, struct file *filp, int on)
451 struct per_user_data *u = filp->private_data;
452 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
455 static int evtchn_open(struct inode *inode, struct file *filp)
457 struct per_user_data *u;
459 u = kzalloc(sizeof(*u), GFP_KERNEL);
463 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
464 if (u->name == NULL) {
469 init_waitqueue_head(&u->evtchn_wait);
471 u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
472 if (u->ring == NULL) {
478 mutex_init(&u->bind_mutex);
479 mutex_init(&u->ring_cons_mutex);
481 filp->private_data = u;
483 return nonseekable_open(inode, filp);
486 static int evtchn_release(struct inode *inode, struct file *filp)
489 struct per_user_data *u = filp->private_data;
491 spin_lock_irq(&port_user_lock);
493 free_page((unsigned long)u->ring);
495 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
496 if (get_port_user(i) != u)
499 disable_irq(irq_from_evtchn(i));
502 spin_unlock_irq(&port_user_lock);
504 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
505 if (get_port_user(i) != u)
508 evtchn_unbind_from_user(get_port_user(i), i);
517 static const struct file_operations evtchn_fops = {
518 .owner = THIS_MODULE,
520 .write = evtchn_write,
521 .unlocked_ioctl = evtchn_ioctl,
523 .fasync = evtchn_fasync,
525 .release = evtchn_release,
529 static struct miscdevice evtchn_miscdev = {
530 .minor = MISC_DYNAMIC_MINOR,
531 .name = "xen/evtchn",
532 .fops = &evtchn_fops,
534 static int __init evtchn_init(void)
541 port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL);
542 if (port_user == NULL)
545 spin_lock_init(&port_user_lock);
547 /* Create '/dev/xen/evtchn'. */
548 err = misc_register(&evtchn_miscdev);
550 printk(KERN_ERR "Could not register /dev/xen/evtchn\n");
554 printk(KERN_INFO "Event-channel device installed.\n");
559 static void __exit evtchn_cleanup(void)
564 misc_deregister(&evtchn_miscdev);
567 module_init(evtchn_init);
568 module_exit(evtchn_cleanup);
570 MODULE_LICENSE("GPL");