[deliverable/linux.git] / drivers / hv / hv_utils_transport.c

/*
 * Kernel/userspace transport abstraction for Hyper-V util driver.
 *
 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */

#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/poll.h>

#include "hyperv_vmbus.h"
#include "hv_utils_transport.h"

static DEFINE_SPINLOCK(hvt_list_lock);
static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);

static void hvt_reset(struct hvutil_transport *hvt)
{
	kfree(hvt->outmsg);
	hvt->outmsg = NULL;
	hvt->outmsg_len = 0;
	if (hvt->on_reset)
		hvt->on_reset();
}

static ssize_t hvt_op_read(struct file *file, char __user *buf,
			   size_t count, loff_t *ppos)
{
	struct hvutil_transport *hvt;
	int ret;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
				     hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
		return -EINTR;

	mutex_lock(&hvt->lock);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		ret = -EBADF;
		goto out_unlock;
	}

	if (!hvt->outmsg) {
		ret = -EAGAIN;
		goto out_unlock;
	}

	if (count < hvt->outmsg_len) {
		ret = -EINVAL;
		goto out_unlock;
	}

	if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
		ret = hvt->outmsg_len;
	else
		ret = -EFAULT;

	kfree(hvt->outmsg);
	hvt->outmsg = NULL;
	hvt->outmsg_len = 0;

out_unlock:
	mutex_unlock(&hvt->lock);
	return ret;
}

static ssize_t hvt_op_write(struct file *file, const char __user *buf,
			    size_t count, loff_t *ppos)
{
	struct hvutil_transport *hvt;
	u8 *inmsg;
	int ret;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	inmsg = memdup_user(buf, count);
	if (IS_ERR(inmsg))
		return PTR_ERR(inmsg);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
		ret = -EBADF;
	else
		ret = hvt->on_msg(inmsg, count);

	kfree(inmsg);

	return ret ? ret : count;
}

static unsigned int hvt_op_poll(struct file *file, poll_table *wait)
{
	struct hvutil_transport *hvt;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	poll_wait(file, &hvt->outmsg_q, wait);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
		return POLLERR | POLLHUP;

	if (hvt->outmsg_len > 0)
		return POLLIN | POLLRDNORM;

	return 0;
}

static int hvt_op_open(struct inode *inode, struct file *file)
{
	struct hvutil_transport *hvt;
	int ret = 0;
	bool issue_reset = false;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	mutex_lock(&hvt->lock);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		ret = -EBADF;
	} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
		/*
		 * Switching to CHARDEV mode. We switch bach to INIT when
		 * device gets released.
		 */
		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
	}
	else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
		/*
		 * We're switching from netlink communication to using char
		 * device. Issue the reset first.
		 */
		issue_reset = true;
		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
	} else {
		ret = -EBUSY;
	}

	if (issue_reset)
		hvt_reset(hvt);

	mutex_unlock(&hvt->lock);

	return ret;
}

static void hvt_transport_free(struct hvutil_transport *hvt)
{
	misc_deregister(&hvt->mdev);
	kfree(hvt->outmsg);
	kfree(hvt);
}

static int hvt_op_release(struct inode *inode, struct file *file)
{
	struct hvutil_transport *hvt;
	int mode_old;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	mutex_lock(&hvt->lock);
	mode_old = hvt->mode;
	if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
		hvt->mode = HVUTIL_TRANSPORT_INIT;
	/*
	 * Cleanup message buffers to avoid spurious messages when the daemon
	 * connects back.
	 */
	hvt_reset(hvt);
	mutex_unlock(&hvt->lock);

	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
		hvt_transport_free(hvt);

	return 0;
}

static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
	struct hvutil_transport *hvt, *hvt_found = NULL;

	spin_lock(&hvt_list_lock);
	list_for_each_entry(hvt, &hvt_list, list) {
		if (hvt->cn_id.idx == msg->id.idx &&
		    hvt->cn_id.val == msg->id.val) {
			hvt_found = hvt;
			break;
		}
	}
	spin_unlock(&hvt_list_lock);
	if (!hvt_found) {
		pr_warn("hvt_cn_callback: spurious message received!\n");
		return;
	}

	/*
	 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
	 * opens the device.
	 */
	mutex_lock(&hvt->lock);
	if (hvt->mode == HVUTIL_TRANSPORT_INIT)
		hvt->mode = HVUTIL_TRANSPORT_NETLINK;

	if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
		hvt_found->on_msg(msg->data, msg->len);
	else
		pr_warn("hvt_cn_callback: unexpected netlink message!\n");
	mutex_unlock(&hvt->lock);
}

int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len)
{
	struct cn_msg *cn_msg;
	int ret = 0;

	if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
	    hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		return -EINVAL;
	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
		cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
		if (!cn_msg)
			return -ENOMEM;
		cn_msg->id.idx = hvt->cn_id.idx;
		cn_msg->id.val = hvt->cn_id.val;
		cn_msg->len = len;
		memcpy(cn_msg->data, msg, len);
		ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
		kfree(cn_msg);
		return ret;
	}
	/* HVUTIL_TRANSPORT_CHARDEV */
	mutex_lock(&hvt->lock);
	if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
		ret = -EINVAL;
		goto out_unlock;
	}

	if (hvt->outmsg) {
		/* Previous message wasn't received */
		ret = -EFAULT;
		goto out_unlock;
	}
	hvt->outmsg = kzalloc(len, GFP_KERNEL);
	if (hvt->outmsg) {
		memcpy(hvt->outmsg, msg, len);
		hvt->outmsg_len = len;
		wake_up_interruptible(&hvt->outmsg_q);
	} else
		ret = -ENOMEM;
out_unlock:
	mutex_unlock(&hvt->lock);
	return ret;
}

struct hvutil_transport *hvutil_transport_init(const char *name,
					       u32 cn_idx, u32 cn_val,
					       int (*on_msg)(void *, int),
					       void (*on_reset)(void))
{
	struct hvutil_transport *hvt;

	hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
	if (!hvt)
		return NULL;

	hvt->cn_id.idx = cn_idx;
	hvt->cn_id.val = cn_val;

	hvt->mdev.minor = MISC_DYNAMIC_MINOR;
	hvt->mdev.name = name;

	hvt->fops.owner = THIS_MODULE;
	hvt->fops.read = hvt_op_read;
	hvt->fops.write = hvt_op_write;
	hvt->fops.poll = hvt_op_poll;
	hvt->fops.open = hvt_op_open;
	hvt->fops.release = hvt_op_release;

	hvt->mdev.fops = &hvt->fops;

	init_waitqueue_head(&hvt->outmsg_q);
	mutex_init(&hvt->lock);

	spin_lock(&hvt_list_lock);
	list_add(&hvt->list, &hvt_list);
	spin_unlock(&hvt_list_lock);

	hvt->on_msg = on_msg;
	hvt->on_reset = on_reset;

	if (misc_register(&hvt->mdev))
		goto err_free_hvt;

	/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
	    cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
		goto err_free_hvt;

	return hvt;

err_free_hvt:
	kfree(hvt);
	return NULL;
}

void hvutil_transport_destroy(struct hvutil_transport *hvt)
{
	int mode_old;

	mutex_lock(&hvt->lock);
	mode_old = hvt->mode;
	hvt->mode = HVUTIL_TRANSPORT_DESTROY;
	wake_up_interruptible(&hvt->outmsg_q);
	mutex_unlock(&hvt->lock);

	/*
	 * In case we were in 'chardev' mode we still have an open fd so we
	 * have to defer freeing the device. Netlink interface can be freed
	 * now.
	 */
	spin_lock(&hvt_list_lock);
	list_del(&hvt->list);
	spin_unlock(&hvt_list_lock);
	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
		cn_del_callback(&hvt->cn_id);

	if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
		hvt_transport_free(hvt);
}
Commit	Line	Data
14b50f80 VK	1	/*
	2	* Kernel/userspace transport abstraction for Hyper-V util driver.
	3	*
	4	* Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License version 2 as published
	8	* by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful, but
	11	* WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	13	* NON INFRINGEMENT. See the GNU General Public License for more
	14	* details.
	15	*
	16	*/
	17
	18	#include <linux/slab.h>
	19	#include <linux/fs.h>
	20	#include <linux/poll.h>
	21
	22	#include "hyperv_vmbus.h"
	23	#include "hv_utils_transport.h"
	24
	25	static DEFINE_SPINLOCK(hvt_list_lock);
	26	static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);
	27
	28	static void hvt_reset(struct hvutil_transport *hvt)
	29	{
14b50f80 VK	30	kfree(hvt->outmsg);
	31	hvt->outmsg = NULL;
	32	hvt->outmsg_len = 0;
14b50f80 VK	33	if (hvt->on_reset)
	34	hvt->on_reset();
	35	}
	36
	37	static ssize_t hvt_op_read(struct file file, char __user buf,
	38	size_t count, loff_t *ppos)
	39	{
	40	struct hvutil_transport *hvt;
	41	int ret;
	42
	43	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	44
a1502566 VK	45	if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 \|\|
a1502566 VK	46	hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
14b50f80 VK	47	return -EINTR;
14b50f80 VK	48
a72f3a4c	49	mutex_lock(&hvt->lock);
a1502566 VK	50
	51	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
	52	ret = -EBADF;
	53	goto out_unlock;
	54	}
	55
14b50f80 VK	56	if (!hvt->outmsg) {
	57	ret = -EAGAIN;
	58	goto out_unlock;
	59	}
	60
	61	if (count < hvt->outmsg_len) {
	62	ret = -EINVAL;
	63	goto out_unlock;
	64	}
	65
	66	if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
	67	ret = hvt->outmsg_len;
	68	else
	69	ret = -EFAULT;
	70
	71	kfree(hvt->outmsg);
	72	hvt->outmsg = NULL;
	73	hvt->outmsg_len = 0;
	74
	75	out_unlock:
a72f3a4c	76	mutex_unlock(&hvt->lock);
14b50f80 VK	77	return ret;
	78	}
	79
	80	static ssize_t hvt_op_write(struct file file, const char __user buf,
	81	size_t count, loff_t *ppos)
	82	{
	83	struct hvutil_transport *hvt;
	84	u8 *inmsg;
1f75338b	85	int ret;
14b50f80 VK	86
	87	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	88
b0035964 OH	89	inmsg = memdup_user(buf, count);
	90	if (IS_ERR(inmsg))
	91	return PTR_ERR(inmsg);
	92
a1502566 VK	93	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
	94	ret = -EBADF;
	95	else
	96	ret = hvt->on_msg(inmsg, count);
1f75338b	97
14b50f80 VK	98	kfree(inmsg);
14b50f80 VK	99
1f75338b	100	return ret ? ret : count;
14b50f80 VK	101	}
	102
	103	static unsigned int hvt_op_poll(struct file file, poll_table wait)
	104	{
	105	struct hvutil_transport *hvt;
	106
	107	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	108
	109	poll_wait(file, &hvt->outmsg_q, wait);
a1502566 VK	110
a1502566 VK	111	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
77b744a5	112	return POLLERR \| POLLHUP;
a1502566	113
14b50f80 VK	114	if (hvt->outmsg_len > 0)
	115	return POLLIN \| POLLRDNORM;
	116
	117	return 0;
	118	}
	119
	120	static int hvt_op_open(struct inode inode, struct file file)
	121	{
	122	struct hvutil_transport *hvt;
a1502566 VK	123	int ret = 0;
a1502566 VK	124	bool issue_reset = false;
14b50f80 VK	125
	126	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	127
a1502566 VK	128	mutex_lock(&hvt->lock);
	129
	130	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
	131	ret = -EBADF;
	132	} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
	133	/*
	134	* Switching to CHARDEV mode. We switch bach to INIT when
	135	* device gets released.
	136	*/
14b50f80	137	hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
a1502566	138	}
14b50f80 VK	139	else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
	140	/*
	141	* We're switching from netlink communication to using char
	142	* device. Issue the reset first.
	143	*/
a1502566	144	issue_reset = true;
14b50f80	145	hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
a1502566 VK	146	} else {
	147	ret = -EBUSY;
	148	}
14b50f80	149
a1502566 VK	150	if (issue_reset)
	151	hvt_reset(hvt);
	152
	153	mutex_unlock(&hvt->lock);
	154
	155	return ret;
14b50f80 VK	156	}
14b50f80 VK	157
9420098a VK	158	static void hvt_transport_free(struct hvutil_transport *hvt)
	159	{
	160	misc_deregister(&hvt->mdev);
	161	kfree(hvt->outmsg);
	162	kfree(hvt);
	163	}
	164
14b50f80 VK	165	static int hvt_op_release(struct inode inode, struct file file)
	166	{
	167	struct hvutil_transport *hvt;
9420098a	168	int mode_old;
14b50f80 VK	169
	170	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	171
a1502566	172	mutex_lock(&hvt->lock);
9420098a	173	mode_old = hvt->mode;
a1502566 VK	174	if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
a1502566 VK	175	hvt->mode = HVUTIL_TRANSPORT_INIT;
14b50f80 VK	176	/*
	177	* Cleanup message buffers to avoid spurious messages when the daemon
	178	* connects back.
	179	*/
	180	hvt_reset(hvt);
a1502566	181	mutex_unlock(&hvt->lock);
14b50f80	182
9420098a VK	183	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
	184	hvt_transport_free(hvt);
	185
14b50f80 VK	186	return 0;
	187	}
	188
	189	static void hvt_cn_callback(struct cn_msg msg, struct netlink_skb_parms nsp)
	190	{
	191	struct hvutil_transport hvt, hvt_found = NULL;
	192
	193	spin_lock(&hvt_list_lock);
	194	list_for_each_entry(hvt, &hvt_list, list) {
	195	if (hvt->cn_id.idx == msg->id.idx &&
	196	hvt->cn_id.val == msg->id.val) {
	197	hvt_found = hvt;
	198	break;
	199	}
	200	}
	201	spin_unlock(&hvt_list_lock);
	202	if (!hvt_found) {
	203	pr_warn("hvt_cn_callback: spurious message received!\n");
	204	return;
	205	}
	206
	207	/*
	208	* Switching to NETLINK mode. Switching to CHARDEV happens when someone
	209	* opens the device.
	210	*/
a1502566	211	mutex_lock(&hvt->lock);
14b50f80 VK	212	if (hvt->mode == HVUTIL_TRANSPORT_INIT)
	213	hvt->mode = HVUTIL_TRANSPORT_NETLINK;
	214
	215	if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
	216	hvt_found->on_msg(msg->data, msg->len);
	217	else
	218	pr_warn("hvt_cn_callback: unexpected netlink message!\n");
a1502566	219	mutex_unlock(&hvt->lock);
14b50f80 VK	220	}
	221
	222	int hvutil_transport_send(struct hvutil_transport hvt, void msg, int len)
	223	{
	224	struct cn_msg *cn_msg;
	225	int ret = 0;
	226
a1502566 VK	227	if (hvt->mode == HVUTIL_TRANSPORT_INIT \|\|
a1502566 VK	228	hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
14b50f80 VK	229	return -EINVAL;
	230	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
	231	cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
9dd6a064	232	if (!cn_msg)
14b50f80 VK	233	return -ENOMEM;
	234	cn_msg->id.idx = hvt->cn_id.idx;
	235	cn_msg->id.val = hvt->cn_id.val;
	236	cn_msg->len = len;
	237	memcpy(cn_msg->data, msg, len);
	238	ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
	239	kfree(cn_msg);
	240	return ret;
	241	}
	242	/* HVUTIL_TRANSPORT_CHARDEV */
a72f3a4c	243	mutex_lock(&hvt->lock);
a1502566 VK	244	if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
	245	ret = -EINVAL;
	246	goto out_unlock;
	247	}
	248
14b50f80 VK	249	if (hvt->outmsg) {
	250	/* Previous message wasn't received */
	251	ret = -EFAULT;
	252	goto out_unlock;
	253	}
	254	hvt->outmsg = kzalloc(len, GFP_KERNEL);
cdc0c0c9 OH	255	if (hvt->outmsg) {
	256	memcpy(hvt->outmsg, msg, len);
	257	hvt->outmsg_len = len;
	258	wake_up_interruptible(&hvt->outmsg_q);
	259	} else
	260	ret = -ENOMEM;
14b50f80	261	out_unlock:
a72f3a4c	262	mutex_unlock(&hvt->lock);
14b50f80 VK	263	return ret;
	264	}
	265
	266	struct hvutil_transport hvutil_transport_init(const char name,
	267	u32 cn_idx, u32 cn_val,
	268	int (on_msg)(void , int),
	269	void (*on_reset)(void))
	270	{
	271	struct hvutil_transport *hvt;
	272
	273	hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
	274	if (!hvt)
	275	return NULL;
	276
	277	hvt->cn_id.idx = cn_idx;
	278	hvt->cn_id.val = cn_val;
	279
	280	hvt->mdev.minor = MISC_DYNAMIC_MINOR;
	281	hvt->mdev.name = name;
	282
	283	hvt->fops.owner = THIS_MODULE;
	284	hvt->fops.read = hvt_op_read;
	285	hvt->fops.write = hvt_op_write;
	286	hvt->fops.poll = hvt_op_poll;
	287	hvt->fops.open = hvt_op_open;
	288	hvt->fops.release = hvt_op_release;
	289
	290	hvt->mdev.fops = &hvt->fops;
	291
	292	init_waitqueue_head(&hvt->outmsg_q);
a72f3a4c	293	mutex_init(&hvt->lock);
14b50f80 VK	294
	295	spin_lock(&hvt_list_lock);
	296	list_add(&hvt->list, &hvt_list);
	297	spin_unlock(&hvt_list_lock);
	298
	299	hvt->on_msg = on_msg;
	300	hvt->on_reset = on_reset;
	301
	302	if (misc_register(&hvt->mdev))
	303	goto err_free_hvt;
	304
	305	/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
	306	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
	307	cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
	308	goto err_free_hvt;
	309
	310	return hvt;
	311
	312	err_free_hvt:
	313	kfree(hvt);
	314	return NULL;
	315	}
	316
	317	void hvutil_transport_destroy(struct hvutil_transport *hvt)
	318	{
9420098a VK	319	int mode_old;
9420098a VK	320
a1502566	321	mutex_lock(&hvt->lock);
9420098a	322	mode_old = hvt->mode;
a1502566 VK	323	hvt->mode = HVUTIL_TRANSPORT_DESTROY;
	324	wake_up_interruptible(&hvt->outmsg_q);
	325	mutex_unlock(&hvt->lock);
	326
9420098a VK	327	/*
	328	* In case we were in 'chardev' mode we still have an open fd so we
	329	* have to defer freeing the device. Netlink interface can be freed
	330	* now.
	331	*/
14b50f80 VK	332	spin_lock(&hvt_list_lock);
	333	list_del(&hvt->list);
	334	spin_unlock(&hvt_list_lock);
	335	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
	336	cn_del_callback(&hvt->cn_id);
9420098a VK	337
	338	if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
	339	hvt_transport_free(hvt);
14b50f80	340	}