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 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
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>
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>
53 #include <linux/vmalloc.h>
56 #include <xen/events.h>
57 #include <xen/evtchn.h>
58 #include <xen/xen-ops.h>
59 #include <asm/xen/hypervisor.h>
61 struct per_user_data
{
62 struct mutex bind_mutex
; /* serialize bind/unbind operations */
63 struct rb_root evtchns
;
64 unsigned int nr_evtchns
;
66 /* Notification ring, accessed via /dev/xen/evtchn. */
67 unsigned int ring_size
;
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 */
73 /* Processes wait on this queue when ring is empty. */
74 wait_queue_head_t evtchn_wait
;
75 struct fasync_struct
*evtchn_async_queue
;
78 domid_t restrict_domid
;
81 #define UNRESTRICTED_DOMID ((domid_t)-1)
85 struct per_user_data
*user
;
90 static void evtchn_free_ring(evtchn_port_t
*ring
)
95 static unsigned int evtchn_ring_offset(struct per_user_data
*u
,
98 return idx
& (u
->ring_size
- 1);
101 static evtchn_port_t
*evtchn_ring_entry(struct per_user_data
*u
,
104 return u
->ring
+ evtchn_ring_offset(u
, idx
);
107 static int add_evtchn(struct per_user_data
*u
, struct user_evtchn
*evtchn
)
109 struct rb_node
**new = &(u
->evtchns
.rb_node
), *parent
= NULL
;
114 struct user_evtchn
*this;
116 this = rb_entry(*new, struct user_evtchn
, node
);
119 if (this->port
< evtchn
->port
)
120 new = &((*new)->rb_left
);
121 else if (this->port
> evtchn
->port
)
122 new = &((*new)->rb_right
);
127 /* Add new node and rebalance tree. */
128 rb_link_node(&evtchn
->node
, parent
, new);
129 rb_insert_color(&evtchn
->node
, &u
->evtchns
);
134 static void del_evtchn(struct per_user_data
*u
, struct user_evtchn
*evtchn
)
137 rb_erase(&evtchn
->node
, &u
->evtchns
);
141 static struct user_evtchn
*find_evtchn(struct per_user_data
*u
,
144 struct rb_node
*node
= u
->evtchns
.rb_node
;
147 struct user_evtchn
*evtchn
;
149 evtchn
= rb_entry(node
, struct user_evtchn
, node
);
151 if (evtchn
->port
< port
)
152 node
= node
->rb_left
;
153 else if (evtchn
->port
> port
)
154 node
= node
->rb_right
;
161 static irqreturn_t
evtchn_interrupt(int irq
, void *data
)
163 struct user_evtchn
*evtchn
= data
;
164 struct per_user_data
*u
= evtchn
->user
;
165 unsigned int prod
, cons
;
167 WARN(!evtchn
->enabled
,
168 "Interrupt for port %u, but apparently not enabled; per-user %p\n",
171 evtchn
->enabled
= false;
173 spin_lock(&u
->ring_prod_lock
);
175 prod
= READ_ONCE(u
->ring_prod
);
176 cons
= READ_ONCE(u
->ring_cons
);
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);
183 wake_up_interruptible(&u
->evtchn_wait
);
184 kill_fasync(&u
->evtchn_async_queue
,
188 u
->ring_overflow
= 1;
190 spin_unlock(&u
->ring_prod_lock
);
195 static ssize_t
evtchn_read(struct file
*file
, char __user
*buf
,
196 size_t count
, loff_t
*ppos
)
199 unsigned int c
, p
, bytes1
= 0, bytes2
= 0;
200 struct per_user_data
*u
= file
->private_data
;
202 /* Whole number of ports. */
203 count
&= ~(sizeof(evtchn_port_t
)-1);
208 if (count
> PAGE_SIZE
)
212 mutex_lock(&u
->ring_cons_mutex
);
215 if (u
->ring_overflow
)
218 c
= READ_ONCE(u
->ring_cons
);
219 p
= READ_ONCE(u
->ring_prod
);
223 mutex_unlock(&u
->ring_cons_mutex
);
225 if (file
->f_flags
& O_NONBLOCK
)
228 rc
= wait_event_interruptible(u
->evtchn_wait
,
229 READ_ONCE(u
->ring_cons
) != READ_ONCE(u
->ring_prod
));
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
);
240 bytes1
= (p
- c
) * sizeof(evtchn_port_t
);
244 /* Truncate chunks according to caller's maximum byte count. */
245 if (bytes1
> count
) {
248 } else if ((bytes1
+ bytes2
) > count
) {
249 bytes2
= count
- bytes1
;
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
) ||
256 copy_to_user(&buf
[bytes1
], &u
->ring
[0], bytes2
)))
259 WRITE_ONCE(u
->ring_cons
, c
+ (bytes1
+ bytes2
) / sizeof(evtchn_port_t
));
260 rc
= bytes1
+ bytes2
;
263 mutex_unlock(&u
->ring_cons_mutex
);
267 static ssize_t
evtchn_write(struct file
*file
, const char __user
*buf
,
268 size_t count
, loff_t
*ppos
)
271 evtchn_port_t
*kbuf
= (evtchn_port_t
*)__get_free_page(GFP_KERNEL
);
272 struct per_user_data
*u
= file
->private_data
;
277 /* Whole number of ports. */
278 count
&= ~(sizeof(evtchn_port_t
)-1);
284 if (count
> PAGE_SIZE
)
288 if (copy_from_user(kbuf
, buf
, count
) != 0)
291 mutex_lock(&u
->bind_mutex
);
293 for (i
= 0; i
< (count
/sizeof(evtchn_port_t
)); i
++) {
294 evtchn_port_t port
= kbuf
[i
];
295 struct user_evtchn
*evtchn
;
297 evtchn
= find_evtchn(u
, port
);
298 if (evtchn
&& !evtchn
->enabled
) {
299 evtchn
->enabled
= true;
300 xen_irq_lateeoi(irq_from_evtchn(port
), 0);
304 mutex_unlock(&u
->bind_mutex
);
309 free_page((unsigned long)kbuf
);
313 static int evtchn_resize_ring(struct per_user_data
*u
)
315 unsigned int new_size
;
316 evtchn_port_t
*new_ring
, *old_ring
;
319 * Ensure the ring is large enough to capture all possible
320 * events. i.e., one free slot for each bound event.
322 if (u
->nr_evtchns
<= u
->ring_size
)
325 if (u
->ring_size
== 0)
328 new_size
= 2 * u
->ring_size
;
330 new_ring
= kvmalloc_array(new_size
, sizeof(*new_ring
), GFP_KERNEL
);
337 * Access to the ring contents is serialized by either the
338 * prod /or/ cons lock so take both when resizing.
340 mutex_lock(&u
->ring_cons_mutex
);
341 spin_lock_irq(&u
->ring_prod_lock
);
344 * Copy the old ring contents to the new ring.
346 * To take care of wrapping, a full ring, and the new index
347 * pointing into the second half, simply copy the old contents
350 * +---------+ +------------------+
351 * |34567 12| -> |34567 1234567 12|
352 * +-----p-c-+ +-------c------p---+
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
));
359 u
->ring_size
= new_size
;
361 spin_unlock_irq(&u
->ring_prod_lock
);
362 mutex_unlock(&u
->ring_cons_mutex
);
364 evtchn_free_ring(old_ring
);
369 static int evtchn_bind_to_user(struct per_user_data
*u
, evtchn_port_t port
)
371 struct user_evtchn
*evtchn
;
372 struct evtchn_close close
;
376 * Ports are never reused, so every caller should pass in a
379 * (Locking not necessary because we haven't registered the
380 * interrupt handler yet, and our caller has already
381 * serialized bind operations.)
384 evtchn
= kzalloc(sizeof(*evtchn
), GFP_KERNEL
);
390 evtchn
->enabled
= true; /* start enabled */
392 rc
= add_evtchn(u
, evtchn
);
396 rc
= evtchn_resize_ring(u
);
400 rc
= bind_evtchn_to_irqhandler_lateeoi(port
, evtchn_interrupt
, 0,
405 rc
= evtchn_make_refcounted(port
);
409 /* bind failed, should close the port now */
411 if (HYPERVISOR_event_channel_op(EVTCHNOP_close
, &close
) != 0)
413 del_evtchn(u
, evtchn
);
417 static void evtchn_unbind_from_user(struct per_user_data
*u
,
418 struct user_evtchn
*evtchn
)
420 int irq
= irq_from_evtchn(evtchn
->port
);
424 unbind_from_irqhandler(irq
, evtchn
);
426 del_evtchn(u
, evtchn
);
429 static long evtchn_ioctl(struct file
*file
,
430 unsigned int cmd
, unsigned long arg
)
433 struct per_user_data
*u
= file
->private_data
;
434 void __user
*uarg
= (void __user
*) arg
;
436 /* Prevent bind from racing with unbind */
437 mutex_lock(&u
->bind_mutex
);
440 case IOCTL_EVTCHN_BIND_VIRQ
: {
441 struct ioctl_evtchn_bind_virq bind
;
442 struct evtchn_bind_virq bind_virq
;
445 if (u
->restrict_domid
!= UNRESTRICTED_DOMID
)
449 if (copy_from_user(&bind
, uarg
, sizeof(bind
)))
452 bind_virq
.virq
= bind
.virq
;
453 bind_virq
.vcpu
= xen_vcpu_nr(0);
454 rc
= HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq
,
459 rc
= evtchn_bind_to_user(u
, bind_virq
.port
);
465 case IOCTL_EVTCHN_BIND_INTERDOMAIN
: {
466 struct ioctl_evtchn_bind_interdomain bind
;
467 struct evtchn_bind_interdomain bind_interdomain
;
470 if (copy_from_user(&bind
, uarg
, sizeof(bind
)))
474 if (u
->restrict_domid
!= UNRESTRICTED_DOMID
&&
475 u
->restrict_domid
!= bind
.remote_domain
)
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
,
485 rc
= evtchn_bind_to_user(u
, bind_interdomain
.local_port
);
487 rc
= bind_interdomain
.local_port
;
491 case IOCTL_EVTCHN_BIND_UNBOUND_PORT
: {
492 struct ioctl_evtchn_bind_unbound_port bind
;
493 struct evtchn_alloc_unbound alloc_unbound
;
496 if (u
->restrict_domid
!= UNRESTRICTED_DOMID
)
500 if (copy_from_user(&bind
, uarg
, sizeof(bind
)))
503 alloc_unbound
.dom
= DOMID_SELF
;
504 alloc_unbound
.remote_dom
= bind
.remote_domain
;
505 rc
= HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound
,
510 rc
= evtchn_bind_to_user(u
, alloc_unbound
.port
);
512 rc
= alloc_unbound
.port
;
516 case IOCTL_EVTCHN_UNBIND
: {
517 struct ioctl_evtchn_unbind unbind
;
518 struct user_evtchn
*evtchn
;
521 if (copy_from_user(&unbind
, uarg
, sizeof(unbind
)))
525 if (unbind
.port
>= xen_evtchn_nr_channels())
529 evtchn
= find_evtchn(u
, unbind
.port
);
533 disable_irq(irq_from_evtchn(unbind
.port
));
534 evtchn_unbind_from_user(u
, evtchn
);
539 case IOCTL_EVTCHN_NOTIFY
: {
540 struct ioctl_evtchn_notify notify
;
541 struct user_evtchn
*evtchn
;
544 if (copy_from_user(¬ify
, uarg
, sizeof(notify
)))
548 evtchn
= find_evtchn(u
, notify
.port
);
550 notify_remote_via_evtchn(notify
.port
);
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
);
569 case IOCTL_EVTCHN_RESTRICT_DOMID
: {
570 struct ioctl_evtchn_restrict_domid ierd
;
573 if (u
->restrict_domid
!= UNRESTRICTED_DOMID
)
577 if (copy_from_user(&ierd
, uarg
, sizeof(ierd
)))
581 if (ierd
.domid
== 0 || ierd
.domid
>= DOMID_FIRST_RESERVED
)
584 u
->restrict_domid
= ierd
.domid
;
594 mutex_unlock(&u
->bind_mutex
);
599 static __poll_t
evtchn_poll(struct file
*file
, poll_table
*wait
)
601 __poll_t mask
= EPOLLOUT
| EPOLLWRNORM
;
602 struct per_user_data
*u
= file
->private_data
;
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
)
612 static int evtchn_fasync(int fd
, struct file
*filp
, int on
)
614 struct per_user_data
*u
= filp
->private_data
;
615 return fasync_helper(fd
, filp
, on
, &u
->evtchn_async_queue
);
618 static int evtchn_open(struct inode
*inode
, struct file
*filp
)
620 struct per_user_data
*u
;
622 u
= kzalloc(sizeof(*u
), GFP_KERNEL
);
626 u
->name
= kasprintf(GFP_KERNEL
, "evtchn:%s", current
->comm
);
627 if (u
->name
== NULL
) {
632 init_waitqueue_head(&u
->evtchn_wait
);
634 mutex_init(&u
->bind_mutex
);
635 mutex_init(&u
->ring_cons_mutex
);
636 spin_lock_init(&u
->ring_prod_lock
);
638 u
->restrict_domid
= UNRESTRICTED_DOMID
;
640 filp
->private_data
= u
;
642 return stream_open(inode
, filp
);
645 static int evtchn_release(struct inode
*inode
, struct file
*filp
)
647 struct per_user_data
*u
= filp
->private_data
;
648 struct rb_node
*node
;
650 while ((node
= u
->evtchns
.rb_node
)) {
651 struct user_evtchn
*evtchn
;
653 evtchn
= rb_entry(node
, struct user_evtchn
, node
);
654 disable_irq(irq_from_evtchn(evtchn
->port
));
655 evtchn_unbind_from_user(u
, evtchn
);
658 evtchn_free_ring(u
->ring
);
665 static const struct file_operations evtchn_fops
= {
666 .owner
= THIS_MODULE
,
668 .write
= evtchn_write
,
669 .unlocked_ioctl
= evtchn_ioctl
,
671 .fasync
= evtchn_fasync
,
673 .release
= evtchn_release
,
677 static struct miscdevice evtchn_miscdev
= {
678 .minor
= MISC_DYNAMIC_MINOR
,
679 .name
= "xen/evtchn",
680 .fops
= &evtchn_fops
,
682 static int __init
evtchn_init(void)
689 /* Create '/dev/xen/evtchn'. */
690 err
= misc_register(&evtchn_miscdev
);
692 pr_err("Could not register /dev/xen/evtchn\n");
696 pr_info("Event-channel device installed\n");
701 static void __exit
evtchn_cleanup(void)
703 misc_deregister(&evtchn_miscdev
);
706 module_init(evtchn_init
);
707 module_exit(evtchn_cleanup
);
709 MODULE_LICENSE("GPL");