[linux-block.git] / drivers / xen / evtchn.c

/******************************************************************************
 * evtchn.c
 *
 * Driver for receiving and demuxing event-channel signals.
 *
 * Copyright (c) 2004-2005, K A Fraser
 * Multi-process extensions Copyright (c) 2004, Steven Smith
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/major.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/cpu.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>

#include <xen/xen.h>
#include <xen/events.h>
#include <xen/evtchn.h>
#include <xen/xen-ops.h>
#include <asm/xen/hypervisor.h>

struct per_user_data {
	struct mutex bind_mutex; /* serialize bind/unbind operations */
	struct rb_root evtchns;
	unsigned int nr_evtchns;

	/* Notification ring, accessed via /dev/xen/evtchn. */
	unsigned int ring_size;
	evtchn_port_t *ring;
	unsigned int ring_cons, ring_prod, ring_overflow;
	struct mutex ring_cons_mutex; /* protect against concurrent readers */
	spinlock_t ring_prod_lock; /* product against concurrent interrupts */

	/* Processes wait on this queue when ring is empty. */
	wait_queue_head_t evtchn_wait;
	struct fasync_struct *evtchn_async_queue;
	const char *name;

	domid_t restrict_domid;
};

#define UNRESTRICTED_DOMID ((domid_t)-1)

struct user_evtchn {
	struct rb_node node;
	struct per_user_data *user;
	evtchn_port_t port;
	bool enabled;
};

static void evtchn_free_ring(evtchn_port_t *ring)
{
	kvfree(ring);
}

static unsigned int evtchn_ring_offset(struct per_user_data *u,
				       unsigned int idx)
{
	return idx & (u->ring_size - 1);
}

static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
					unsigned int idx)
{
	return u->ring + evtchn_ring_offset(u, idx);
}

static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
{
	struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;

	u->nr_evtchns++;

	while (*new) {
		struct user_evtchn *this;

		this = rb_entry(*new, struct user_evtchn, node);

		parent = *new;
		if (this->port < evtchn->port)
			new = &((*new)->rb_left);
		else if (this->port > evtchn->port)
			new = &((*new)->rb_right);
		else
			return -EEXIST;
	}

	/* Add new node and rebalance tree. */
	rb_link_node(&evtchn->node, parent, new);
	rb_insert_color(&evtchn->node, &u->evtchns);

	return 0;
}

static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
{
	u->nr_evtchns--;
	rb_erase(&evtchn->node, &u->evtchns);
	kfree(evtchn);
}

static struct user_evtchn *find_evtchn(struct per_user_data *u,
				       evtchn_port_t port)
{
	struct rb_node *node = u->evtchns.rb_node;

	while (node) {
		struct user_evtchn *evtchn;

		evtchn = rb_entry(node, struct user_evtchn, node);

		if (evtchn->port < port)
			node = node->rb_left;
		else if (evtchn->port > port)
			node = node->rb_right;
		else
			return evtchn;
	}
	return NULL;
}

static irqreturn_t evtchn_interrupt(int irq, void *data)
{
	struct user_evtchn *evtchn = data;
	struct per_user_data *u = evtchn->user;
	unsigned int prod, cons;

	WARN(!evtchn->enabled,
	     "Interrupt for port %u, but apparently not enabled; per-user %p\n",
	     evtchn->port, u);

	evtchn->enabled = false;

	spin_lock(&u->ring_prod_lock);

	prod = READ_ONCE(u->ring_prod);
	cons = READ_ONCE(u->ring_cons);

	if ((prod - cons) < u->ring_size) {
		*evtchn_ring_entry(u, prod) = evtchn->port;
		smp_wmb(); /* Ensure ring contents visible */
		WRITE_ONCE(u->ring_prod, prod + 1);
		if (cons == prod) {
			wake_up_interruptible(&u->evtchn_wait);
			kill_fasync(&u->evtchn_async_queue,
				    SIGIO, POLL_IN);
		}
	} else
		u->ring_overflow = 1;

	spin_unlock(&u->ring_prod_lock);

	return IRQ_HANDLED;
}

static ssize_t evtchn_read(struct file *file, char __user *buf,
			   size_t count, loff_t *ppos)
{
	int rc;
	unsigned int c, p, bytes1 = 0, bytes2 = 0;
	struct per_user_data *u = file->private_data;

	/* Whole number of ports. */
	count &= ~(sizeof(evtchn_port_t)-1);

	if (count == 0)
		return 0;

	if (count > PAGE_SIZE)
		count = PAGE_SIZE;

	for (;;) {
		mutex_lock(&u->ring_cons_mutex);

		rc = -EFBIG;
		if (u->ring_overflow)
			goto unlock_out;

		c = READ_ONCE(u->ring_cons);
		p = READ_ONCE(u->ring_prod);
		if (c != p)
			break;

		mutex_unlock(&u->ring_cons_mutex);

		if (file->f_flags & O_NONBLOCK)
			return -EAGAIN;

		rc = wait_event_interruptible(u->evtchn_wait,
			READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));
		if (rc)
			return rc;
	}

	/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
	if (((c ^ p) & u->ring_size) != 0) {
		bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
			sizeof(evtchn_port_t);
		bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
	} else {
		bytes1 = (p - c) * sizeof(evtchn_port_t);
		bytes2 = 0;
	}

	/* Truncate chunks according to caller's maximum byte count. */
	if (bytes1 > count) {
		bytes1 = count;
		bytes2 = 0;
	} else if ((bytes1 + bytes2) > count) {
		bytes2 = count - bytes1;
	}

	rc = -EFAULT;
	smp_rmb(); /* Ensure that we see the port before we copy it. */
	if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
	    ((bytes2 != 0) &&
	     copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
		goto unlock_out;

	WRITE_ONCE(u->ring_cons, c + (bytes1 + bytes2) / sizeof(evtchn_port_t));
	rc = bytes1 + bytes2;

 unlock_out:
	mutex_unlock(&u->ring_cons_mutex);
	return rc;
}

static ssize_t evtchn_write(struct file *file, const char __user *buf,
			    size_t count, loff_t *ppos)
{
	int rc, i;
	evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
	struct per_user_data *u = file->private_data;

	if (kbuf == NULL)
		return -ENOMEM;

	/* Whole number of ports. */
	count &= ~(sizeof(evtchn_port_t)-1);

	rc = 0;
	if (count == 0)
		goto out;

	if (count > PAGE_SIZE)
		count = PAGE_SIZE;

	rc = -EFAULT;
	if (copy_from_user(kbuf, buf, count) != 0)
		goto out;

	mutex_lock(&u->bind_mutex);

	for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
		evtchn_port_t port = kbuf[i];
		struct user_evtchn *evtchn;

		evtchn = find_evtchn(u, port);
		if (evtchn && !evtchn->enabled) {
			evtchn->enabled = true;
			xen_irq_lateeoi(irq_from_evtchn(port), 0);
		}
	}

	mutex_unlock(&u->bind_mutex);

	rc = count;

 out:
	free_page((unsigned long)kbuf);
	return rc;
}

static int evtchn_resize_ring(struct per_user_data *u)
{
	unsigned int new_size;
	evtchn_port_t *new_ring, *old_ring;

	/*
	 * Ensure the ring is large enough to capture all possible
	 * events. i.e., one free slot for each bound event.
	 */
	if (u->nr_evtchns <= u->ring_size)
		return 0;

	if (u->ring_size == 0)
		new_size = 64;
	else
		new_size = 2 * u->ring_size;

	new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
	if (!new_ring)
		return -ENOMEM;

	old_ring = u->ring;

	/*
	 * Access to the ring contents is serialized by either the
	 * prod /or/ cons lock so take both when resizing.
	 */
	mutex_lock(&u->ring_cons_mutex);
	spin_lock_irq(&u->ring_prod_lock);

	/*
	 * Copy the old ring contents to the new ring.
	 *
	 * To take care of wrapping, a full ring, and the new index
	 * pointing into the second half, simply copy the old contents
	 * twice.
	 *
	 * +---------+    +------------------+
	 * |34567  12| -> |34567  1234567  12|
	 * +-----p-c-+    +-------c------p---+
	 */
	memcpy(new_ring, old_ring, u->ring_size * sizeof(*u->ring));
	memcpy(new_ring + u->ring_size, old_ring,
	       u->ring_size * sizeof(*u->ring));

	u->ring = new_ring;
	u->ring_size = new_size;

	spin_unlock_irq(&u->ring_prod_lock);
	mutex_unlock(&u->ring_cons_mutex);

	evtchn_free_ring(old_ring);

	return 0;
}

static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
{
	struct user_evtchn *evtchn;
	struct evtchn_close close;
	int rc = 0;

	/*
	 * Ports are never reused, so every caller should pass in a
	 * unique port.
	 *
	 * (Locking not necessary because we haven't registered the
	 * interrupt handler yet, and our caller has already
	 * serialized bind operations.)
	 */

	evtchn = kzalloc(sizeof(*evtchn), GFP_KERNEL);
	if (!evtchn)
		return -ENOMEM;

	evtchn->user = u;
	evtchn->port = port;
	evtchn->enabled = true; /* start enabled */

	rc = add_evtchn(u, evtchn);
	if (rc < 0)
		goto err;

	rc = evtchn_resize_ring(u);
	if (rc < 0)
		goto err;

	rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
					       u->name, evtchn);
	if (rc < 0)
		goto err;

	rc = evtchn_make_refcounted(port);
	return rc;

err:
	/* bind failed, should close the port now */
	close.port = port;
	if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
		BUG();
	del_evtchn(u, evtchn);
	return rc;
}

static void evtchn_unbind_from_user(struct per_user_data *u,
				    struct user_evtchn *evtchn)
{
	int irq = irq_from_evtchn(evtchn->port);

	BUG_ON(irq < 0);

	unbind_from_irqhandler(irq, evtchn);

	del_evtchn(u, evtchn);
}

static long evtchn_ioctl(struct file *file,
			 unsigned int cmd, unsigned long arg)
{
	int rc;
	struct per_user_data *u = file->private_data;
	void __user *uarg = (void __user *) arg;

	/* Prevent bind from racing with unbind */
	mutex_lock(&u->bind_mutex);

	switch (cmd) {
	case IOCTL_EVTCHN_BIND_VIRQ: {
		struct ioctl_evtchn_bind_virq bind;
		struct evtchn_bind_virq bind_virq;

		rc = -EACCES;
		if (u->restrict_domid != UNRESTRICTED_DOMID)
			break;

		rc = -EFAULT;
		if (copy_from_user(&bind, uarg, sizeof(bind)))
			break;

		bind_virq.virq = bind.virq;
		bind_virq.vcpu = xen_vcpu_nr(0);
		rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
						 &bind_virq);
		if (rc != 0)
			break;

		rc = evtchn_bind_to_user(u, bind_virq.port);
		if (rc == 0)
			rc = bind_virq.port;
		break;
	}

	case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
		struct ioctl_evtchn_bind_interdomain bind;
		struct evtchn_bind_interdomain bind_interdomain;

		rc = -EFAULT;
		if (copy_from_user(&bind, uarg, sizeof(bind)))
			break;

		rc = -EACCES;
		if (u->restrict_domid != UNRESTRICTED_DOMID &&
		    u->restrict_domid != bind.remote_domain)
			break;

		bind_interdomain.remote_dom  = bind.remote_domain;
		bind_interdomain.remote_port = bind.remote_port;
		rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
						 &bind_interdomain);
		if (rc != 0)
			break;

		rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
		if (rc == 0)
			rc = bind_interdomain.local_port;
		break;
	}

	case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
		struct ioctl_evtchn_bind_unbound_port bind;
		struct evtchn_alloc_unbound alloc_unbound;

		rc = -EACCES;
		if (u->restrict_domid != UNRESTRICTED_DOMID)
			break;

		rc = -EFAULT;
		if (copy_from_user(&bind, uarg, sizeof(bind)))
			break;

		alloc_unbound.dom        = DOMID_SELF;
		alloc_unbound.remote_dom = bind.remote_domain;
		rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
						 &alloc_unbound);
		if (rc != 0)
			break;

		rc = evtchn_bind_to_user(u, alloc_unbound.port);
		if (rc == 0)
			rc = alloc_unbound.port;
		break;
	}

	case IOCTL_EVTCHN_UNBIND: {
		struct ioctl_evtchn_unbind unbind;
		struct user_evtchn *evtchn;

		rc = -EFAULT;
		if (copy_from_user(&unbind, uarg, sizeof(unbind)))
			break;

		rc = -EINVAL;
		if (unbind.port >= xen_evtchn_nr_channels())
			break;

		rc = -ENOTCONN;
		evtchn = find_evtchn(u, unbind.port);
		if (!evtchn)
			break;

		disable_irq(irq_from_evtchn(unbind.port));
		evtchn_unbind_from_user(u, evtchn);
		rc = 0;
		break;
	}

	case IOCTL_EVTCHN_NOTIFY: {
		struct ioctl_evtchn_notify notify;
		struct user_evtchn *evtchn;

		rc = -EFAULT;
		if (copy_from_user(&notify, uarg, sizeof(notify)))
			break;

		rc = -ENOTCONN;
		evtchn = find_evtchn(u, notify.port);
		if (evtchn) {
			notify_remote_via_evtchn(notify.port);
			rc = 0;
		}
		break;
	}

	case IOCTL_EVTCHN_RESET: {
		/* Initialise the ring to empty. Clear errors. */
		mutex_lock(&u->ring_cons_mutex);
		spin_lock_irq(&u->ring_prod_lock);
		WRITE_ONCE(u->ring_cons, 0);
		WRITE_ONCE(u->ring_prod, 0);
		u->ring_overflow = 0;
		spin_unlock_irq(&u->ring_prod_lock);
		mutex_unlock(&u->ring_cons_mutex);
		rc = 0;
		break;
	}

	case IOCTL_EVTCHN_RESTRICT_DOMID: {
		struct ioctl_evtchn_restrict_domid ierd;

		rc = -EACCES;
		if (u->restrict_domid != UNRESTRICTED_DOMID)
			break;

		rc = -EFAULT;
		if (copy_from_user(&ierd, uarg, sizeof(ierd)))
		    break;

		rc = -EINVAL;
		if (ierd.domid == 0 || ierd.domid >= DOMID_FIRST_RESERVED)
			break;

		u->restrict_domid = ierd.domid;
		rc = 0;

		break;
	}

	default:
		rc = -ENOSYS;
		break;
	}
	mutex_unlock(&u->bind_mutex);

	return rc;
}

static __poll_t evtchn_poll(struct file *file, poll_table *wait)
{
	__poll_t mask = EPOLLOUT | EPOLLWRNORM;
	struct per_user_data *u = file->private_data;

	poll_wait(file, &u->evtchn_wait, wait);
	if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))
		mask |= EPOLLIN | EPOLLRDNORM;
	if (u->ring_overflow)
		mask = EPOLLERR;
	return mask;
}

static int evtchn_fasync(int fd, struct file *filp, int on)
{
	struct per_user_data *u = filp->private_data;
	return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
}

static int evtchn_open(struct inode *inode, struct file *filp)
{
	struct per_user_data *u;

	u = kzalloc(sizeof(*u), GFP_KERNEL);
	if (u == NULL)
		return -ENOMEM;

	u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
	if (u->name == NULL) {
		kfree(u);
		return -ENOMEM;
	}

	init_waitqueue_head(&u->evtchn_wait);

	mutex_init(&u->bind_mutex);
	mutex_init(&u->ring_cons_mutex);
	spin_lock_init(&u->ring_prod_lock);

	u->restrict_domid = UNRESTRICTED_DOMID;

	filp->private_data = u;

	return stream_open(inode, filp);
}

static int evtchn_release(struct inode *inode, struct file *filp)
{
	struct per_user_data *u = filp->private_data;
	struct rb_node *node;

	while ((node = u->evtchns.rb_node)) {
		struct user_evtchn *evtchn;

		evtchn = rb_entry(node, struct user_evtchn, node);
		disable_irq(irq_from_evtchn(evtchn->port));
		evtchn_unbind_from_user(u, evtchn);
	}

	evtchn_free_ring(u->ring);
	kfree(u->name);
	kfree(u);

	return 0;
}

static const struct file_operations evtchn_fops = {
	.owner   = THIS_MODULE,
	.read    = evtchn_read,
	.write   = evtchn_write,
	.unlocked_ioctl = evtchn_ioctl,
	.poll    = evtchn_poll,
	.fasync  = evtchn_fasync,
	.open    = evtchn_open,
	.release = evtchn_release,
	.llseek	 = no_llseek,
};

static struct miscdevice evtchn_miscdev = {
	.minor        = MISC_DYNAMIC_MINOR,
	.name         = "xen/evtchn",
	.fops         = &evtchn_fops,
};
static int __init evtchn_init(void)
{
	int err;

	if (!xen_domain())
		return -ENODEV;

	/* Create '/dev/xen/evtchn'. */
	err = misc_register(&evtchn_miscdev);
	if (err != 0) {
		pr_err("Could not register /dev/xen/evtchn\n");
		return err;
	}

	pr_info("Event-channel device installed\n");

	return 0;
}

static void __exit evtchn_cleanup(void)
{
	misc_deregister(&evtchn_miscdev);
}

module_init(evtchn_init);
module_exit(evtchn_cleanup);

MODULE_LICENSE("GPL");
Commit	Line	Data
f7116284 IC	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
283c0972 JP	34	#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
283c0972 JP	35
f7116284 IC	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>
f7116284 IC	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>
f7116284 IC	50	#include <linux/mutex.h>
f7116284 IC	51	#include <linux/cpu.h>
86200154 DV	52	#include <linux/mm.h>
86200154 DV	53	#include <linux/vmalloc.h>
1ccbf534 JF	54
1ccbf534 JF	55	#include <xen/xen.h>
f7116284 IC	56	#include <xen/events.h>
f7116284 IC	57	#include <xen/evtchn.h>
cbbb4682	58	#include <xen/xen-ops.h>
f7116284 IC	59	#include <asm/xen/hypervisor.h>
	60
	61	struct per_user_data {
0a4666b5	62	struct mutex bind_mutex; /* serialize bind/unbind operations */
73cc4bb0	63	struct rb_root evtchns;
86200154	64	unsigned int nr_evtchns;
0a4666b5	65
f7116284	66	/* Notification ring, accessed via /dev/xen/evtchn. */
86200154	67	unsigned int ring_size;
f7116284 IC	68	evtchn_port_t *ring;
	69	unsigned int ring_cons, ring_prod, ring_overflow;
	70	struct mutex ring_cons_mutex; /* protect against concurrent readers */
73cc4bb0	71	spinlock_t ring_prod_lock; /* product against concurrent interrupts */
f7116284 IC	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;
fbc872c3 DV	77
fbc872c3 DV	78	domid_t restrict_domid;
f7116284 IC	79	};
f7116284 IC	80
fbc872c3 DV	81	#define UNRESTRICTED_DOMID ((domid_t)-1)
fbc872c3 DV	82
73cc4bb0 DV	83	struct user_evtchn {
	84	struct rb_node node;
	85	struct per_user_data *user;
0102e4ef	86	evtchn_port_t port;
73cc4bb0 DV	87	bool enabled;
73cc4bb0 DV	88	};
f7116284	89
86200154 DV	90	static void evtchn_free_ring(evtchn_port_t *ring)
	91	{
	92	kvfree(ring);
	93	}
	94
	95	static unsigned int evtchn_ring_offset(struct per_user_data *u,
	96	unsigned int idx)
	97	{
	98	return idx & (u->ring_size - 1);
	99	}
	100
	101	static 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
73cc4bb0	107	static int add_evtchn(struct per_user_data u, struct user_evtchn evtchn)
e3cc067b	108	{
73cc4bb0	109	struct rb_node *new = &(u->evtchns.rb_node), parent = NULL;
e3cc067b	110
86200154 DV	111	u->nr_evtchns++;
86200154 DV	112
73cc4bb0 DV	113	while (*new) {
	114	struct user_evtchn *this;
	115
2f60b288	116	this = rb_entry(*new, struct user_evtchn, node);
73cc4bb0 DV	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;
e3cc067b JF	132	}
e3cc067b JF	133
73cc4bb0	134	static void del_evtchn(struct per_user_data u, struct user_evtchn evtchn)
e3cc067b	135	{
86200154	136	u->nr_evtchns--;
73cc4bb0 DV	137	rb_erase(&evtchn->node, &u->evtchns);
73cc4bb0 DV	138	kfree(evtchn);
e3cc067b JF	139	}
e3cc067b JF	140
0102e4ef YY	141	static struct user_evtchn find_evtchn(struct per_user_data u,
0102e4ef YY	142	evtchn_port_t port)
e3cc067b	143	{
73cc4bb0 DV	144	struct rb_node *node = u->evtchns.rb_node;
	145
	146	while (node) {
	147	struct user_evtchn *evtchn;
	148
2f60b288	149	evtchn = rb_entry(node, struct user_evtchn, node);
73cc4bb0 DV	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;
e3cc067b JF	159	}
e3cc067b JF	160
70697d54	161	static irqreturn_t evtchn_interrupt(int irq, void *data)
f7116284	162	{
73cc4bb0 DV	163	struct user_evtchn *evtchn = data;
73cc4bb0 DV	164	struct per_user_data *u = evtchn->user;
6977c0b5	165	unsigned int prod, cons;
e3cc067b	166
73cc4bb0	167	WARN(!evtchn->enabled,
0102e4ef	168	"Interrupt for port %u, but apparently not enabled; per-user %p\n",
73cc4bb0	169	evtchn->port, u);
f7116284	170
73cc4bb0 DV	171	evtchn->enabled = false;
	172
	173	spin_lock(&u->ring_prod_lock);
f7116284	174
6977c0b5 JG	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;
d5669959	180	smp_wmb(); /* Ensure ring contents visible */
6977c0b5 JG	181	WRITE_ONCE(u->ring_prod, prod + 1);
6977c0b5 JG	182	if (cons == prod) {
f7116284 IC	183	wake_up_interruptible(&u->evtchn_wait);
	184	kill_fasync(&u->evtchn_async_queue,
	185	SIGIO, POLL_IN);
	186	}
e3cc067b	187	} else
f7116284	188	u->ring_overflow = 1;
f7116284	189
73cc4bb0	190	spin_unlock(&u->ring_prod_lock);
f7116284 IC	191
	192	return IRQ_HANDLED;
	193	}
	194
	195	static 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
6977c0b5 JG	218	c = READ_ONCE(u->ring_cons);
6977c0b5 JG	219	p = READ_ONCE(u->ring_prod);
f7116284 IC	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,
6977c0b5	229	READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));
f7116284 IC	230	if (rc)
	231	return rc;
	232	}
	233
	234	/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
86200154 DV	235	if (((c ^ p) & u->ring_size) != 0) {
86200154 DV	236	bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
f7116284	237	sizeof(evtchn_port_t);
86200154	238	bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
f7116284 IC	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;
d5669959	253	smp_rmb(); /* Ensure that we see the port before we copy it. */
86200154	254	if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) \|\|
f7116284 IC	255	((bytes2 != 0) &&
	256	copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
	257	goto unlock_out;
	258
6977c0b5	259	WRITE_ONCE(u->ring_cons, c + (bytes1 + bytes2) / sizeof(evtchn_port_t));
f7116284 IC	260	rc = bytes1 + bytes2;
	261
	262	unlock_out:
	263	mutex_unlock(&u->ring_cons_mutex);
	264	return rc;
	265	}
	266
	267	static 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
73cc4bb0	291	mutex_lock(&u->bind_mutex);
e3cc067b JF	292
e3cc067b JF	293	for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
0102e4ef	294	evtchn_port_t port = kbuf[i];
73cc4bb0	295	struct user_evtchn *evtchn;
e3cc067b	296
73cc4bb0 DV	297	evtchn = find_evtchn(u, port);
	298	if (evtchn && !evtchn->enabled) {
	299	evtchn->enabled = true;
c44b849c	300	xen_irq_lateeoi(irq_from_evtchn(port), 0);
e3cc067b JF	301	}
	302	}
	303
73cc4bb0	304	mutex_unlock(&u->bind_mutex);
f7116284 IC	305
	306	rc = count;
	307
	308	out:
	309	free_page((unsigned long)kbuf);
	310	return rc;
	311	}
	312
86200154 DV	313	static int evtchn_resize_ring(struct per_user_data *u)
	314	{
	315	unsigned int new_size;
	316	evtchn_port_t new_ring, old_ring;
86200154 DV	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
344476e1	330	new_ring = kvmalloc_array(new_size, sizeof(*new_ring), GFP_KERNEL);
86200154 DV	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	*
27e0e638 JB	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.
86200154 DV	349	*
86200154 DV	350	* +---------+ +------------------+
27e0e638 JB	351	* \|34567 12\| -> \|34567 1234567 12\|
27e0e638 JB	352	* +-----p-c-+ +-------c------p---+
86200154	353	*/
27e0e638 JB	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));
86200154 DV	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
0102e4ef	369	static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
f7116284	370	{
73cc4bb0 DV	371	struct user_evtchn *evtchn;
73cc4bb0 DV	372	struct evtchn_close close;
f7116284 IC	373	int rc = 0;
f7116284 IC	374
0a4666b5 JF	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	*/
73cc4bb0 DV	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;
f7116284	395
86200154 DV	396	rc = evtchn_resize_ring(u);
	397	if (rc < 0)
	398	goto err;
	399
c44b849c JG	400	rc = bind_evtchn_to_irqhandler_lateeoi(port, evtchn_interrupt, 0,
c44b849c JG	401	u->name, evtchn);
73cc4bb0 DV	402	if (rc < 0)
73cc4bb0 DV	403	goto err;
0a4666b5	404
73cc4bb0 DV	405	rc = evtchn_make_refcounted(port);
	406	return rc;
	407
	408	err:
	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);
f7116284 IC	414	return rc;
	415	}
	416
73cc4bb0 DV	417	static void evtchn_unbind_from_user(struct per_user_data *u,
73cc4bb0 DV	418	struct user_evtchn *evtchn)
f7116284	419	{
73cc4bb0	420	int irq = irq_from_evtchn(evtchn->port);
f7116284	421
e7e44e44 WL	422	BUG_ON(irq < 0);
e7e44e44 WL	423
73cc4bb0	424	unbind_from_irqhandler(irq, evtchn);
0a4666b5	425
73cc4bb0	426	del_evtchn(u, evtchn);
f7116284 IC	427	}
	428
	429	static 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
0a4666b5 JF	436	/* Prevent bind from racing with unbind */
	437	mutex_lock(&u->bind_mutex);
	438
f7116284 IC	439	switch (cmd) {
	440	case IOCTL_EVTCHN_BIND_VIRQ: {
	441	struct ioctl_evtchn_bind_virq bind;
	442	struct evtchn_bind_virq bind_virq;
	443
fbc872c3 DV	444	rc = -EACCES;
	445	if (u->restrict_domid != UNRESTRICTED_DOMID)
	446	break;
	447
f7116284 IC	448	rc = -EFAULT;
	449	if (copy_from_user(&bind, uarg, sizeof(bind)))
	450	break;
	451
	452	bind_virq.virq = bind.virq;
cbbb4682	453	bind_virq.vcpu = xen_vcpu_nr(0);
f7116284 IC	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
fbc872c3 DV	473	rc = -EACCES;
	474	if (u->restrict_domid != UNRESTRICTED_DOMID &&
	475	u->restrict_domid != bind.remote_domain)
	476	break;
	477
f7116284 IC	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);
67473b81	486	if (rc == 0)
f7116284 IC	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
fbc872c3 DV	495	rc = -EACCES;
	496	if (u->restrict_domid != UNRESTRICTED_DOMID)
	497	break;
	498
f7116284 IC	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;
73cc4bb0	518	struct user_evtchn *evtchn;
f7116284 IC	519
	520	rc = -EFAULT;
	521	if (copy_from_user(&unbind, uarg, sizeof(unbind)))
	522	break;
	523
	524	rc = -EINVAL;
0dc0064a	525	if (unbind.port >= xen_evtchn_nr_channels())
f7116284 IC	526	break;
f7116284 IC	527
f7116284	528	rc = -ENOTCONN;
73cc4bb0 DV	529	evtchn = find_evtchn(u, unbind.port);
73cc4bb0 DV	530	if (!evtchn)
f7116284	531	break;
f7116284	532
3f5e554f	533	disable_irq(irq_from_evtchn(unbind.port));
73cc4bb0	534	evtchn_unbind_from_user(u, evtchn);
f7116284 IC	535	rc = 0;
	536	break;
	537	}
	538
	539	case IOCTL_EVTCHN_NOTIFY: {
	540	struct ioctl_evtchn_notify notify;
73cc4bb0	541	struct user_evtchn *evtchn;
f7116284 IC	542
	543	rc = -EFAULT;
	544	if (copy_from_user(&notify, uarg, sizeof(notify)))
	545	break;
	546
73cc4bb0 DV	547	rc = -ENOTCONN;
	548	evtchn = find_evtchn(u, notify.port);
	549	if (evtchn) {
f7116284 IC	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);
73cc4bb0	559	spin_lock_irq(&u->ring_prod_lock);
6977c0b5 JG	560	WRITE_ONCE(u->ring_cons, 0);
	561	WRITE_ONCE(u->ring_prod, 0);
	562	u->ring_overflow = 0;
73cc4bb0	563	spin_unlock_irq(&u->ring_prod_lock);
f7116284 IC	564	mutex_unlock(&u->ring_cons_mutex);
	565	rc = 0;
	566	break;
	567	}
	568
fbc872c3 DV	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
f7116284 IC	590	default:
	591	rc = -ENOSYS;
	592	break;
	593	}
0a4666b5	594	mutex_unlock(&u->bind_mutex);
f7116284 IC	595
	596	return rc;
	597	}
	598
afc9a42b	599	static __poll_t evtchn_poll(struct file file, poll_table wait)
f7116284	600	{
a9a08845	601	__poll_t mask = EPOLLOUT \| EPOLLWRNORM;
f7116284 IC	602	struct per_user_data *u = file->private_data;
	603
	604	poll_wait(file, &u->evtchn_wait, wait);
6977c0b5	605	if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))
a9a08845	606	mask \|= EPOLLIN \| EPOLLRDNORM;
f7116284	607	if (u->ring_overflow)
a9a08845	608	mask = EPOLLERR;
f7116284 IC	609	return mask;
	610	}
	611
	612	static 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
	618	static 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
0a4666b5	634	mutex_init(&u->bind_mutex);
f7116284	635	mutex_init(&u->ring_cons_mutex);
73cc4bb0	636	spin_lock_init(&u->ring_prod_lock);
f7116284	637
fbc872c3 DV	638	u->restrict_domid = UNRESTRICTED_DOMID;
fbc872c3 DV	639
f7116284 IC	640	filp->private_data = u;
f7116284 IC	641
c5bf68fe	642	return stream_open(inode, filp);
f7116284 IC	643	}
	644
	645	static int evtchn_release(struct inode inode, struct file filp)
	646	{
f7116284	647	struct per_user_data *u = filp->private_data;
73cc4bb0	648	struct rb_node *node;
f7116284	649
73cc4bb0 DV	650	while ((node = u->evtchns.rb_node)) {
73cc4bb0 DV	651	struct user_evtchn *evtchn;
f7116284	652
73cc4bb0 DV	653	evtchn = rb_entry(node, struct user_evtchn, node);
	654	disable_irq(irq_from_evtchn(evtchn->port));
	655	evtchn_unbind_from_user(u, evtchn);
3f5e554f JF	656	}
3f5e554f JF	657
86200154	658	evtchn_free_ring(u->ring);
f7116284 IC	659	kfree(u->name);
	660	kfree(u);
	661
	662	return 0;
	663	}
	664
	665	static 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,
bc7fc5e3	674	.llseek = no_llseek,
f7116284 IC	675	};
	676
	677	static struct miscdevice evtchn_miscdev = {
	678	.minor = MISC_DYNAMIC_MINOR,
376d908f	679	.name = "xen/evtchn",
f7116284 IC	680	.fops = &evtchn_fops,
	681	};
	682	static int __init evtchn_init(void)
	683	{
	684	int err;
	685
	686	if (!xen_domain())
	687	return -ENODEV;
	688
18283ea7	689	/* Create '/dev/xen/evtchn'. */
f7116284 IC	690	err = misc_register(&evtchn_miscdev);
f7116284 IC	691	if (err != 0) {
283c0972	692	pr_err("Could not register /dev/xen/evtchn\n");
f7116284 IC	693	return err;
	694	}
	695
283c0972	696	pr_info("Event-channel device installed\n");
f7116284 IC	697
	698	return 0;
	699	}
	700
	701	static void __exit evtchn_cleanup(void)
	702	{
	703	misc_deregister(&evtchn_miscdev);
	704	}
	705
	706	module_init(evtchn_init);
	707	module_exit(evtchn_cleanup);
	708
	709	MODULE_LICENSE("GPL");