[mirror_ubuntu-bionic-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) {
			if (err == -EFAULT) /* Fix idiotic error code */
				err = -EIO;
			return err;
		}
		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) {
			if (err == -EFAULT) /* Fix idiotic error code */
				err = -EIO;
			return err;
		}
		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);
	int ret = 0;

	lock_kernel();
	cpu = iminor(file->f_path.dentry->d_inode);

	if (cpu >= NR_CPUS || !cpu_online(cpu)) {
		ret = -ENXIO;	/* No such CPU */
		goto out;
	}
	c = &cpu_data(cpu);
	if (!cpu_has(c, X86_FEATURE_MSR))
		ret = -EIO;	/* MSR not supported */
out:
	unlock_kernel();
	return ret;
}

/*
 * 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_drvdata(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
				    NULL, "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]);
c6f31932 PA	82	if (err) {
	83	if (err == -EFAULT) /* Fix idiotic error code */
	84	err = -EIO;
	85	return err;
	86	}
1da177e4 LT	87	if (copy_to_user(tmp, &data, 8))
	88	return -EFAULT;
	89	tmp += 2;
	90	}
	91
	92	return ((char __user *)tmp) - buf;
	93	}
	94
	95	static ssize_t msr_write(struct file file, const char __user buf,
	96	size_t count, loff_t *ppos)
	97	{
	98	const u32 __user tmp = (const u32 __user )buf;
	99	u32 data[2];
1da177e4	100	u32 reg = *ppos;
aab4c5a5	101	int cpu = iminor(file->f_path.dentry->d_inode);
1da177e4 LT	102	int err;
	103
	104	if (count % 8)
	105	return -EINVAL; /* Invalid chunk size */
	106
f475ff35	107	for (; count; count -= 8) {
1da177e4 LT	108	if (copy_from_user(&data, tmp, 8))
1da177e4 LT	109	return -EFAULT;
78a62d2c	110	err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
c6f31932 PA	111	if (err) {
	112	if (err == -EFAULT) /* Fix idiotic error code */
	113	err = -EIO;
	114	return err;
	115	}
1da177e4 LT	116	tmp += 2;
	117	}
	118
	119	return ((char __user *)tmp) - buf;
	120	}
	121
	122	static int msr_open(struct inode inode, struct file file)
	123	{
aab4c5a5	124	unsigned int cpu = iminor(file->f_path.dentry->d_inode);
92cb7612	125	struct cpuinfo_x86 *c = &cpu_data(cpu);
5119e92e	126	int ret = 0;
1da177e4	127
5119e92e JC	128	lock_kernel();
5119e92e JC	129	cpu = iminor(file->f_path.dentry->d_inode);
1da177e4	130
5119e92e JC	131	if (cpu >= NR_CPUS \|\| !cpu_online(cpu)) {
	132	ret = -ENXIO; /* No such CPU */
	133	goto out;
	134	}
	135	c = &cpu_data(cpu);
	136	if (!cpu_has(c, X86_FEATURE_MSR))
	137	ret = -EIO; /* MSR not supported */
	138	out:
	139	unlock_kernel();
967060d0	140	return ret;
1da177e4 LT	141	}
	142
	143	/*
	144	* File operations we support
	145	*/
5dfe4c96	146	static const struct file_operations msr_fops = {
1da177e4 LT	147	.owner = THIS_MODULE,
	148	.llseek = msr_seek,
	149	.read = msr_read,
	150	.write = msr_write,
	151	.open = msr_open,
	152	};
	153
38048983	154	static int __cpuinit msr_device_create(int cpu)
1da177e4	155	{
a271aaf1	156	struct device *dev;
1da177e4	157
3bfd49c8 GKH	158	dev = device_create_drvdata(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
3bfd49c8 GKH	159	NULL, "msr%d", cpu);
881a841f AM	160	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
	161	}
	162
	163	static void msr_device_destroy(int cpu)
	164	{
	165	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
1da177e4 LT	166	}
1da177e4 LT	167
761c4bf8	168	static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
e09793bb	169	unsigned long action, void *hcpu)
1da177e4 LT	170	{
1da177e4 LT	171	unsigned int cpu = (unsigned long)hcpu;
881a841f	172	int err = 0;
1da177e4 LT	173
1da177e4 LT	174	switch (action) {
881a841f	175	case CPU_UP_PREPARE:
881a841f	176	err = msr_device_create(cpu);
1da177e4	177	break;
881a841f	178	case CPU_UP_CANCELED:
b844eba2	179	case CPU_UP_CANCELED_FROZEN:
1da177e4	180	case CPU_DEAD:
881a841f	181	msr_device_destroy(cpu);
1da177e4 LT	182	break;
1da177e4 LT	183	}
881a841f	184	return err ? NOTIFY_BAD : NOTIFY_OK;
1da177e4 LT	185	}
1da177e4 LT	186
c72258c7	187	static struct notifier_block __refdata msr_class_cpu_notifier = {
1da177e4 LT	188	.notifier_call = msr_class_cpu_callback,
	189	};
	190
	191	static int __init msr_init(void)
	192	{
	193	int i, err = 0;
	194	i = 0;
	195
	196	if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
	197	printk(KERN_ERR "msr: unable to get major %d for msr\n",
	198	MSR_MAJOR);
	199	err = -EBUSY;
	200	goto out;
	201	}
8874b414	202	msr_class = class_create(THIS_MODULE, "msr");
1da177e4 LT	203	if (IS_ERR(msr_class)) {
	204	err = PTR_ERR(msr_class);
	205	goto out_chrdev;
	206	}
	207	for_each_online_cpu(i) {
a271aaf1	208	err = msr_device_create(i);
1da177e4 LT	209	if (err != 0)
	210	goto out_class;
	211	}
e09793bb	212	register_hotcpu_notifier(&msr_class_cpu_notifier);
1da177e4 LT	213
	214	err = 0;
	215	goto out;
	216
	217	out_class:
	218	i = 0;
	219	for_each_online_cpu(i)
881a841f	220	msr_device_destroy(i);
8874b414	221	class_destroy(msr_class);
1da177e4 LT	222	out_chrdev:
	223	unregister_chrdev(MSR_MAJOR, "cpu/msr");
	224	out:
	225	return err;
	226	}
	227
	228	static void __exit msr_exit(void)
	229	{
	230	int cpu = 0;
	231	for_each_online_cpu(cpu)
881a841f	232	msr_device_destroy(cpu);
8874b414	233	class_destroy(msr_class);
1da177e4	234	unregister_chrdev(MSR_MAJOR, "cpu/msr");
e09793bb	235	unregister_hotcpu_notifier(&msr_class_cpu_notifier);
1da177e4 LT	236	}
	237
	238	module_init(msr_init);
	239	module_exit(msr_exit)
	240
	241	MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
	242	MODULE_DESCRIPTION("x86 generic MSR driver");
	243	MODULE_LICENSE("GPL");