[mirror_ubuntu-hirsute-kernel.git] / arch / x86 / kernel / msr.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
 *   USA; either version 2 of the License, or (at your option) any later
 *   version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * x86 MSR access device
 *
 * This device is accessed by lseek() to the appropriate register number
 * and then read/write in chunks of 8 bytes.  A larger size means multiple
 * reads or writes of the same register.
 *
 * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
 * an SMP box will direct the access to CPU %d.
 */

#include <linux/module.h>

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/notifier.h>

#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/uaccess.h>
#include <asm/system.h>

static struct class *msr_class;

static loff_t msr_seek(struct file *file, loff_t offset, int orig)
{
	loff_t ret;
	struct inode *inode = file->f_mapping->host;

	mutex_lock(&inode->i_mutex);
	switch (orig) {
	case 0:
		file->f_pos = offset;
		ret = file->f_pos;
		break;
	case 1:
		file->f_pos += offset;
		ret = file->f_pos;
		break;
	default:
		ret = -EINVAL;
	}
	mutex_unlock(&inode->i_mutex);
	return ret;
}

static ssize_t msr_read(struct file *file, char __user *buf,
			size_t count, loff_t *ppos)
{
	u32 __user *tmp = (u32 __user *) buf;
	u32 data[2];
	u32 reg = *ppos;
	int cpu = iminor(file->f_path.dentry->d_inode);
	int err;

	if (count % 8)
		return -EINVAL;	/* Invalid chunk size */

	for (; count; count -= 8) {
		err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
		if (err)
			return -EIO;
		if (copy_to_user(tmp, &data, 8))
			return -EFAULT;
		tmp += 2;
	}

	return ((char __user *)tmp) - buf;
}

static ssize_t msr_write(struct file *file, const char __user *buf,
			 size_t count, loff_t *ppos)
{
	const u32 __user *tmp = (const u32 __user *)buf;
	u32 data[2];
	u32 reg = *ppos;
	int cpu = iminor(file->f_path.dentry->d_inode);
	int err;

	if (count % 8)
		return -EINVAL;	/* Invalid chunk size */

	for (; count; count -= 8) {
		if (copy_from_user(&data, tmp, 8))
			return -EFAULT;
		err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
		if (err)
			return -EIO;
		tmp += 2;
	}

	return ((char __user *)tmp) - buf;
}

static int msr_open(struct inode *inode, struct file *file)
{
	unsigned int cpu = iminor(file->f_path.dentry->d_inode);
	struct cpuinfo_x86 *c = &cpu_data(cpu);

	if (cpu >= NR_CPUS || !cpu_online(cpu))
		return -ENXIO;	/* No such CPU */
	if (!cpu_has(c, X86_FEATURE_MSR))
		return -EIO;	/* MSR not supported */

	return 0;
}

/*
 * File operations we support
 */
static const struct file_operations msr_fops = {
	.owner = THIS_MODULE,
	.llseek = msr_seek,
	.read = msr_read,
	.write = msr_write,
	.open = msr_open,
};

static int __cpuinit msr_device_create(int cpu)
{
	struct device *dev;

	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
			    "msr%d", cpu);
	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
}

static void msr_device_destroy(int cpu)
{
	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
}

static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
				unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long)hcpu;
	int err = 0;

	switch (action) {
	case CPU_UP_PREPARE:
		err = msr_device_create(cpu);
		break;
	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
	case CPU_DEAD:
		msr_device_destroy(cpu);
		break;
	}
	return err ? NOTIFY_BAD : NOTIFY_OK;
}

static struct notifier_block __refdata msr_class_cpu_notifier = {
	.notifier_call = msr_class_cpu_callback,
};

static int __init msr_init(void)
{
	int i, err = 0;
	i = 0;

	if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
		printk(KERN_ERR "msr: unable to get major %d for msr\n",
		       MSR_MAJOR);
		err = -EBUSY;
		goto out;
	}
	msr_class = class_create(THIS_MODULE, "msr");
	if (IS_ERR(msr_class)) {
		err = PTR_ERR(msr_class);
		goto out_chrdev;
	}
	for_each_online_cpu(i) {
		err = msr_device_create(i);
		if (err != 0)
			goto out_class;
	}
	register_hotcpu_notifier(&msr_class_cpu_notifier);

	err = 0;
	goto out;

out_class:
	i = 0;
	for_each_online_cpu(i)
		msr_device_destroy(i);
	class_destroy(msr_class);
out_chrdev:
	unregister_chrdev(MSR_MAJOR, "cpu/msr");
out:
	return err;
}

static void __exit msr_exit(void)
{
	int cpu = 0;
	for_each_online_cpu(cpu)
		msr_device_destroy(cpu);
	class_destroy(msr_class);
	unregister_chrdev(MSR_MAJOR, "cpu/msr");
	unregister_hotcpu_notifier(&msr_class_cpu_notifier);
}

module_init(msr_init);
module_exit(msr_exit)

MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
MODULE_DESCRIPTION("x86 generic MSR driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4	1	/* ----------------------------------------------------------------------- *
2b06ac86 PA	2	*
2b06ac86 PA	3	* Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
1da177e4 LT	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
	8	* USA; either version 2 of the License, or (at your option) any later
	9	* version; incorporated herein by reference.
	10	*
	11	* ----------------------------------------------------------------------- */
	12
	13	/*
1da177e4 LT	14	* x86 MSR access device
	15	*
	16	* This device is accessed by lseek() to the appropriate register number
	17	* and then read/write in chunks of 8 bytes. A larger size means multiple
	18	* reads or writes of the same register.
	19	*
	20	* This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
	21	* an SMP box will direct the access to CPU %d.
	22	*/
	23
	24	#include <linux/module.h>
1da177e4 LT	25
	26	#include <linux/types.h>
	27	#include <linux/errno.h>
	28	#include <linux/fcntl.h>
	29	#include <linux/init.h>
	30	#include <linux/poll.h>
	31	#include <linux/smp.h>
	32	#include <linux/smp_lock.h>
	33	#include <linux/major.h>
	34	#include <linux/fs.h>
	35	#include <linux/device.h>
	36	#include <linux/cpu.h>
	37	#include <linux/notifier.h>
	38
	39	#include <asm/processor.h>
	40	#include <asm/msr.h>
	41	#include <asm/uaccess.h>
	42	#include <asm/system.h>
	43
8874b414	44	static struct class *msr_class;
1da177e4	45
1da177e4 LT	46	static loff_t msr_seek(struct file *file, loff_t offset, int orig)
1da177e4 LT	47	{
2b06ac86 PA	48	loff_t ret;
2b06ac86 PA	49	struct inode *inode = file->f_mapping->host;
1da177e4	50
2b06ac86	51	mutex_lock(&inode->i_mutex);
1da177e4 LT	52	switch (orig) {
	53	case 0:
	54	file->f_pos = offset;
	55	ret = file->f_pos;
	56	break;
	57	case 1:
	58	file->f_pos += offset;
	59	ret = file->f_pos;
2b06ac86 PA	60	break;
	61	default:
	62	ret = -EINVAL;
1da177e4	63	}
2b06ac86	64	mutex_unlock(&inode->i_mutex);
1da177e4 LT	65	return ret;
	66	}
	67
94a9fa41 PC	68	static ssize_t msr_read(struct file file, char __user buf,
94a9fa41 PC	69	size_t count, loff_t *ppos)
1da177e4 LT	70	{
	71	u32 __user tmp = (u32 __user ) buf;
	72	u32 data[2];
1da177e4	73	u32 reg = *ppos;
aab4c5a5	74	int cpu = iminor(file->f_path.dentry->d_inode);
1da177e4 LT	75	int err;
	76
	77	if (count % 8)
	78	return -EINVAL; /* Invalid chunk size */
	79
6926d570	80	for (; count; count -= 8) {
78a62d2c	81	err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
1da177e4	82	if (err)
78a62d2c	83	return -EIO;
1da177e4 LT	84	if (copy_to_user(tmp, &data, 8))
	85	return -EFAULT;
	86	tmp += 2;
	87	}
	88
	89	return ((char __user *)tmp) - buf;
	90	}
	91
	92	static ssize_t msr_write(struct file file, const char __user buf,
	93	size_t count, loff_t *ppos)
	94	{
	95	const u32 __user tmp = (const u32 __user )buf;
	96	u32 data[2];
1da177e4	97	u32 reg = *ppos;
aab4c5a5	98	int cpu = iminor(file->f_path.dentry->d_inode);
1da177e4 LT	99	int err;
	100
	101	if (count % 8)
	102	return -EINVAL; /* Invalid chunk size */
	103
f475ff35	104	for (; count; count -= 8) {
1da177e4 LT	105	if (copy_from_user(&data, tmp, 8))
1da177e4 LT	106	return -EFAULT;
78a62d2c	107	err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
1da177e4	108	if (err)
78a62d2c	109	return -EIO;
1da177e4 LT	110	tmp += 2;
	111	}
	112
	113	return ((char __user *)tmp) - buf;
	114	}
	115
	116	static int msr_open(struct inode inode, struct file file)
	117	{
aab4c5a5	118	unsigned int cpu = iminor(file->f_path.dentry->d_inode);
92cb7612	119	struct cpuinfo_x86 *c = &cpu_data(cpu);
1da177e4 LT	120
	121	if (cpu >= NR_CPUS \|\| !cpu_online(cpu))
	122	return -ENXIO; /* No such CPU */
	123	if (!cpu_has(c, X86_FEATURE_MSR))
	124	return -EIO; /* MSR not supported */
	125
	126	return 0;
	127	}
	128
	129	/*
	130	* File operations we support
	131	*/
5dfe4c96	132	static const struct file_operations msr_fops = {
1da177e4 LT	133	.owner = THIS_MODULE,
	134	.llseek = msr_seek,
	135	.read = msr_read,
	136	.write = msr_write,
	137	.open = msr_open,
	138	};
	139
38048983	140	static int __cpuinit msr_device_create(int cpu)
1da177e4	141	{
a271aaf1	142	struct device *dev;
1da177e4	143
881a841f AM	144	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
	145	"msr%d", cpu);
	146	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
	147	}
	148
	149	static void msr_device_destroy(int cpu)
	150	{
	151	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
1da177e4 LT	152	}
1da177e4 LT	153
761c4bf8	154	static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
e09793bb	155	unsigned long action, void *hcpu)
1da177e4 LT	156	{
1da177e4 LT	157	unsigned int cpu = (unsigned long)hcpu;
881a841f	158	int err = 0;
1da177e4 LT	159
1da177e4 LT	160	switch (action) {
881a841f	161	case CPU_UP_PREPARE:
881a841f	162	err = msr_device_create(cpu);
1da177e4	163	break;
881a841f	164	case CPU_UP_CANCELED:
b844eba2	165	case CPU_UP_CANCELED_FROZEN:
1da177e4	166	case CPU_DEAD:
881a841f	167	msr_device_destroy(cpu);
1da177e4 LT	168	break;
1da177e4 LT	169	}
881a841f	170	return err ? NOTIFY_BAD : NOTIFY_OK;
1da177e4 LT	171	}
1da177e4 LT	172
c72258c7	173	static struct notifier_block __refdata msr_class_cpu_notifier = {
1da177e4 LT	174	.notifier_call = msr_class_cpu_callback,
	175	};
	176
	177	static int __init msr_init(void)
	178	{
	179	int i, err = 0;
	180	i = 0;
	181
	182	if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
	183	printk(KERN_ERR "msr: unable to get major %d for msr\n",
	184	MSR_MAJOR);
	185	err = -EBUSY;
	186	goto out;
	187	}
8874b414	188	msr_class = class_create(THIS_MODULE, "msr");
1da177e4 LT	189	if (IS_ERR(msr_class)) {
	190	err = PTR_ERR(msr_class);
	191	goto out_chrdev;
	192	}
	193	for_each_online_cpu(i) {
a271aaf1	194	err = msr_device_create(i);
1da177e4 LT	195	if (err != 0)
	196	goto out_class;
	197	}
e09793bb	198	register_hotcpu_notifier(&msr_class_cpu_notifier);
1da177e4 LT	199
	200	err = 0;
	201	goto out;
	202
	203	out_class:
	204	i = 0;
	205	for_each_online_cpu(i)
881a841f	206	msr_device_destroy(i);
8874b414	207	class_destroy(msr_class);
1da177e4 LT	208	out_chrdev:
	209	unregister_chrdev(MSR_MAJOR, "cpu/msr");
	210	out:
	211	return err;
	212	}
	213
	214	static void __exit msr_exit(void)
	215	{
	216	int cpu = 0;
	217	for_each_online_cpu(cpu)
881a841f	218	msr_device_destroy(cpu);
8874b414	219	class_destroy(msr_class);
1da177e4	220	unregister_chrdev(MSR_MAJOR, "cpu/msr");
e09793bb	221	unregister_hotcpu_notifier(&msr_class_cpu_notifier);
1da177e4 LT	222	}
	223
	224	module_init(msr_init);
	225	module_exit(msr_exit)
	226
	227	MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
	228	MODULE_DESCRIPTION("x86 generic MSR driver");
	229	MODULE_LICENSE("GPL");