Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* ----------------------------------------------------------------------- * |
2b06ac86 PA |
2 | * |
3 | * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved | |
ff55df53 | 4 | * Copyright 2009 Intel Corporation; author: H. Peter Anvin |
1da177e4 LT |
5 | * |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139, | |
9 | * USA; either version 2 of the License, or (at your option) any later | |
10 | * version; incorporated herein by reference. | |
11 | * | |
12 | * ----------------------------------------------------------------------- */ | |
13 | ||
14 | /* | |
1da177e4 LT |
15 | * x86 MSR access device |
16 | * | |
17 | * This device is accessed by lseek() to the appropriate register number | |
18 | * and then read/write in chunks of 8 bytes. A larger size means multiple | |
19 | * reads or writes of the same register. | |
20 | * | |
21 | * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on | |
22 | * an SMP box will direct the access to CPU %d. | |
23 | */ | |
24 | ||
25 | #include <linux/module.h> | |
1da177e4 LT |
26 | |
27 | #include <linux/types.h> | |
28 | #include <linux/errno.h> | |
29 | #include <linux/fcntl.h> | |
30 | #include <linux/init.h> | |
31 | #include <linux/poll.h> | |
32 | #include <linux/smp.h> | |
1da177e4 LT |
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> | |
448dd2fa | 38 | #include <linux/uaccess.h> |
5a0e3ad6 | 39 | #include <linux/gfp.h> |
1da177e4 LT |
40 | |
41 | #include <asm/processor.h> | |
42 | #include <asm/msr.h> | |
1da177e4 | 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) |
47 | { | |
2b06ac86 PA |
48 | loff_t ret; |
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, |
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; |
6131ffaa | 74 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
75 | int err = 0; |
76 | ssize_t bytes = 0; | |
1da177e4 LT |
77 | |
78 | if (count % 8) | |
79 | return -EINVAL; /* Invalid chunk size */ | |
80 | ||
6926d570 | 81 | for (; count; count -= 8) { |
78a62d2c | 82 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
0cc0213e | 83 | if (err) |
85f1cb60 | 84 | break; |
85f1cb60 PA |
85 | if (copy_to_user(tmp, &data, 8)) { |
86 | err = -EFAULT; | |
87 | break; | |
c6f31932 | 88 | } |
1da177e4 | 89 | tmp += 2; |
85f1cb60 | 90 | bytes += 8; |
1da177e4 LT |
91 | } |
92 | ||
85f1cb60 | 93 | return bytes ? bytes : err; |
1da177e4 LT |
94 | } |
95 | ||
96 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
97 | size_t count, loff_t *ppos) | |
98 | { | |
99 | const u32 __user *tmp = (const u32 __user *)buf; | |
100 | u32 data[2]; | |
1da177e4 | 101 | u32 reg = *ppos; |
6131ffaa | 102 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
103 | int err = 0; |
104 | ssize_t bytes = 0; | |
1da177e4 LT |
105 | |
106 | if (count % 8) | |
107 | return -EINVAL; /* Invalid chunk size */ | |
108 | ||
f475ff35 | 109 | for (; count; count -= 8) { |
85f1cb60 PA |
110 | if (copy_from_user(&data, tmp, 8)) { |
111 | err = -EFAULT; | |
112 | break; | |
113 | } | |
78a62d2c | 114 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
0cc0213e | 115 | if (err) |
85f1cb60 | 116 | break; |
1da177e4 | 117 | tmp += 2; |
85f1cb60 | 118 | bytes += 8; |
1da177e4 LT |
119 | } |
120 | ||
85f1cb60 | 121 | return bytes ? bytes : err; |
1da177e4 LT |
122 | } |
123 | ||
ff55df53 PA |
124 | static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) |
125 | { | |
126 | u32 __user *uregs = (u32 __user *)arg; | |
127 | u32 regs[8]; | |
6131ffaa | 128 | int cpu = iminor(file_inode(file)); |
ff55df53 PA |
129 | int err; |
130 | ||
131 | switch (ioc) { | |
132 | case X86_IOC_RDMSR_REGS: | |
133 | if (!(file->f_mode & FMODE_READ)) { | |
134 | err = -EBADF; | |
135 | break; | |
136 | } | |
137 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
138 | err = -EFAULT; | |
139 | break; | |
140 | } | |
141 | err = rdmsr_safe_regs_on_cpu(cpu, regs); | |
142 | if (err) | |
143 | break; | |
144 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
145 | err = -EFAULT; | |
146 | break; | |
147 | ||
148 | case X86_IOC_WRMSR_REGS: | |
149 | if (!(file->f_mode & FMODE_WRITE)) { | |
150 | err = -EBADF; | |
151 | break; | |
152 | } | |
153 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
154 | err = -EFAULT; | |
155 | break; | |
156 | } | |
157 | err = wrmsr_safe_regs_on_cpu(cpu, regs); | |
158 | if (err) | |
159 | break; | |
160 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
161 | err = -EFAULT; | |
162 | break; | |
163 | ||
164 | default: | |
165 | err = -ENOTTY; | |
166 | break; | |
167 | } | |
168 | ||
169 | return err; | |
170 | } | |
171 | ||
1da177e4 LT |
172 | static int msr_open(struct inode *inode, struct file *file) |
173 | { | |
6131ffaa | 174 | unsigned int cpu = iminor(file_inode(file)); |
494c2ebf | 175 | struct cpuinfo_x86 *c; |
1da177e4 | 176 | |
c903f045 AC |
177 | if (!capable(CAP_SYS_RAWIO)) |
178 | return -EPERM; | |
179 | ||
d6c30405 FW |
180 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
181 | return -ENXIO; /* No such CPU */ | |
182 | ||
5119e92e JC |
183 | c = &cpu_data(cpu); |
184 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
d6c30405 FW |
185 | return -EIO; /* MSR not supported */ |
186 | ||
187 | return 0; | |
1da177e4 LT |
188 | } |
189 | ||
190 | /* | |
191 | * File operations we support | |
192 | */ | |
5dfe4c96 | 193 | static const struct file_operations msr_fops = { |
1da177e4 LT |
194 | .owner = THIS_MODULE, |
195 | .llseek = msr_seek, | |
196 | .read = msr_read, | |
197 | .write = msr_write, | |
198 | .open = msr_open, | |
ff55df53 PA |
199 | .unlocked_ioctl = msr_ioctl, |
200 | .compat_ioctl = msr_ioctl, | |
1da177e4 LT |
201 | }; |
202 | ||
148f9bb8 | 203 | static int msr_device_create(int cpu) |
1da177e4 | 204 | { |
a271aaf1 | 205 | struct device *dev; |
1da177e4 | 206 | |
a9b12619 GKH |
207 | dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, |
208 | "msr%d", cpu); | |
881a841f AM |
209 | return IS_ERR(dev) ? PTR_ERR(dev) : 0; |
210 | } | |
211 | ||
212 | static void msr_device_destroy(int cpu) | |
213 | { | |
214 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
1da177e4 LT |
215 | } |
216 | ||
148f9bb8 PG |
217 | static int msr_class_cpu_callback(struct notifier_block *nfb, |
218 | unsigned long action, void *hcpu) | |
1da177e4 LT |
219 | { |
220 | unsigned int cpu = (unsigned long)hcpu; | |
881a841f | 221 | int err = 0; |
1da177e4 LT |
222 | |
223 | switch (action) { | |
881a841f | 224 | case CPU_UP_PREPARE: |
881a841f | 225 | err = msr_device_create(cpu); |
1da177e4 | 226 | break; |
881a841f | 227 | case CPU_UP_CANCELED: |
b844eba2 | 228 | case CPU_UP_CANCELED_FROZEN: |
1da177e4 | 229 | case CPU_DEAD: |
881a841f | 230 | msr_device_destroy(cpu); |
1da177e4 LT |
231 | break; |
232 | } | |
a94247e7 | 233 | return notifier_from_errno(err); |
1da177e4 LT |
234 | } |
235 | ||
c72258c7 | 236 | static struct notifier_block __refdata msr_class_cpu_notifier = { |
1da177e4 LT |
237 | .notifier_call = msr_class_cpu_callback, |
238 | }; | |
239 | ||
2c9ede55 | 240 | static char *msr_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
241 | { |
242 | return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); | |
243 | } | |
244 | ||
1da177e4 LT |
245 | static int __init msr_init(void) |
246 | { | |
247 | int i, err = 0; | |
248 | i = 0; | |
249 | ||
0b962d47 | 250 | if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { |
1da177e4 LT |
251 | printk(KERN_ERR "msr: unable to get major %d for msr\n", |
252 | MSR_MAJOR); | |
253 | err = -EBUSY; | |
254 | goto out; | |
255 | } | |
8874b414 | 256 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
257 | if (IS_ERR(msr_class)) { |
258 | err = PTR_ERR(msr_class); | |
259 | goto out_chrdev; | |
260 | } | |
e454cea2 | 261 | msr_class->devnode = msr_devnode; |
a2db672a | 262 | get_online_cpus(); |
1da177e4 | 263 | for_each_online_cpu(i) { |
a271aaf1 | 264 | err = msr_device_create(i); |
1da177e4 LT |
265 | if (err != 0) |
266 | goto out_class; | |
267 | } | |
e09793bb | 268 | register_hotcpu_notifier(&msr_class_cpu_notifier); |
a2db672a | 269 | put_online_cpus(); |
1da177e4 LT |
270 | |
271 | err = 0; | |
272 | goto out; | |
273 | ||
274 | out_class: | |
275 | i = 0; | |
276 | for_each_online_cpu(i) | |
881a841f | 277 | msr_device_destroy(i); |
a2db672a | 278 | put_online_cpus(); |
8874b414 | 279 | class_destroy(msr_class); |
1da177e4 | 280 | out_chrdev: |
0b962d47 | 281 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
1da177e4 LT |
282 | out: |
283 | return err; | |
284 | } | |
285 | ||
286 | static void __exit msr_exit(void) | |
287 | { | |
288 | int cpu = 0; | |
a2db672a | 289 | get_online_cpus(); |
1da177e4 | 290 | for_each_online_cpu(cpu) |
881a841f | 291 | msr_device_destroy(cpu); |
8874b414 | 292 | class_destroy(msr_class); |
da482474 | 293 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
e09793bb | 294 | unregister_hotcpu_notifier(&msr_class_cpu_notifier); |
a2db672a | 295 | put_online_cpus(); |
1da177e4 LT |
296 | } |
297 | ||
298 | module_init(msr_init); | |
299 | module_exit(msr_exit) | |
300 | ||
301 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
302 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
303 | MODULE_LICENSE("GPL"); |