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 | ||
951a18c6 FF |
25 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
26 | ||
1da177e4 | 27 | #include <linux/module.h> |
1da177e4 LT |
28 | |
29 | #include <linux/types.h> | |
30 | #include <linux/errno.h> | |
31 | #include <linux/fcntl.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/poll.h> | |
34 | #include <linux/smp.h> | |
1da177e4 LT |
35 | #include <linux/major.h> |
36 | #include <linux/fs.h> | |
37 | #include <linux/device.h> | |
38 | #include <linux/cpu.h> | |
39 | #include <linux/notifier.h> | |
448dd2fa | 40 | #include <linux/uaccess.h> |
5a0e3ad6 | 41 | #include <linux/gfp.h> |
1da177e4 LT |
42 | |
43 | #include <asm/processor.h> | |
44 | #include <asm/msr.h> | |
1da177e4 | 45 | |
8874b414 | 46 | static struct class *msr_class; |
1da177e4 | 47 | |
1da177e4 LT |
48 | static loff_t msr_seek(struct file *file, loff_t offset, int orig) |
49 | { | |
2b06ac86 | 50 | loff_t ret; |
12249873 | 51 | struct inode *inode = file_inode(file); |
1da177e4 | 52 | |
2b06ac86 | 53 | mutex_lock(&inode->i_mutex); |
1da177e4 | 54 | switch (orig) { |
03452d27 | 55 | case SEEK_SET: |
1da177e4 LT |
56 | file->f_pos = offset; |
57 | ret = file->f_pos; | |
58 | break; | |
03452d27 | 59 | case SEEK_CUR: |
1da177e4 LT |
60 | file->f_pos += offset; |
61 | ret = file->f_pos; | |
2b06ac86 PA |
62 | break; |
63 | default: | |
64 | ret = -EINVAL; | |
1da177e4 | 65 | } |
2b06ac86 | 66 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
67 | return ret; |
68 | } | |
69 | ||
94a9fa41 PC |
70 | static ssize_t msr_read(struct file *file, char __user *buf, |
71 | size_t count, loff_t *ppos) | |
1da177e4 LT |
72 | { |
73 | u32 __user *tmp = (u32 __user *) buf; | |
74 | u32 data[2]; | |
1da177e4 | 75 | u32 reg = *ppos; |
6131ffaa | 76 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
77 | int err = 0; |
78 | ssize_t bytes = 0; | |
1da177e4 LT |
79 | |
80 | if (count % 8) | |
81 | return -EINVAL; /* Invalid chunk size */ | |
82 | ||
6926d570 | 83 | for (; count; count -= 8) { |
78a62d2c | 84 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
0cc0213e | 85 | if (err) |
85f1cb60 | 86 | break; |
85f1cb60 PA |
87 | if (copy_to_user(tmp, &data, 8)) { |
88 | err = -EFAULT; | |
89 | break; | |
c6f31932 | 90 | } |
1da177e4 | 91 | tmp += 2; |
85f1cb60 | 92 | bytes += 8; |
1da177e4 LT |
93 | } |
94 | ||
85f1cb60 | 95 | return bytes ? bytes : err; |
1da177e4 LT |
96 | } |
97 | ||
98 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
99 | size_t count, loff_t *ppos) | |
100 | { | |
101 | const u32 __user *tmp = (const u32 __user *)buf; | |
102 | u32 data[2]; | |
1da177e4 | 103 | u32 reg = *ppos; |
6131ffaa | 104 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
105 | int err = 0; |
106 | ssize_t bytes = 0; | |
1da177e4 LT |
107 | |
108 | if (count % 8) | |
109 | return -EINVAL; /* Invalid chunk size */ | |
110 | ||
f475ff35 | 111 | for (; count; count -= 8) { |
85f1cb60 PA |
112 | if (copy_from_user(&data, tmp, 8)) { |
113 | err = -EFAULT; | |
114 | break; | |
115 | } | |
78a62d2c | 116 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
0cc0213e | 117 | if (err) |
85f1cb60 | 118 | break; |
1da177e4 | 119 | tmp += 2; |
85f1cb60 | 120 | bytes += 8; |
1da177e4 LT |
121 | } |
122 | ||
85f1cb60 | 123 | return bytes ? bytes : err; |
1da177e4 LT |
124 | } |
125 | ||
ff55df53 PA |
126 | static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) |
127 | { | |
128 | u32 __user *uregs = (u32 __user *)arg; | |
129 | u32 regs[8]; | |
6131ffaa | 130 | int cpu = iminor(file_inode(file)); |
ff55df53 PA |
131 | int err; |
132 | ||
133 | switch (ioc) { | |
134 | case X86_IOC_RDMSR_REGS: | |
135 | if (!(file->f_mode & FMODE_READ)) { | |
136 | err = -EBADF; | |
137 | break; | |
138 | } | |
139 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
140 | err = -EFAULT; | |
141 | break; | |
142 | } | |
143 | err = rdmsr_safe_regs_on_cpu(cpu, regs); | |
144 | if (err) | |
145 | break; | |
146 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
147 | err = -EFAULT; | |
148 | break; | |
149 | ||
150 | case X86_IOC_WRMSR_REGS: | |
151 | if (!(file->f_mode & FMODE_WRITE)) { | |
152 | err = -EBADF; | |
153 | break; | |
154 | } | |
155 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
156 | err = -EFAULT; | |
157 | break; | |
158 | } | |
159 | err = wrmsr_safe_regs_on_cpu(cpu, regs); | |
160 | if (err) | |
161 | break; | |
162 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
163 | err = -EFAULT; | |
164 | break; | |
165 | ||
166 | default: | |
167 | err = -ENOTTY; | |
168 | break; | |
169 | } | |
170 | ||
171 | return err; | |
172 | } | |
173 | ||
1da177e4 LT |
174 | static int msr_open(struct inode *inode, struct file *file) |
175 | { | |
6131ffaa | 176 | unsigned int cpu = iminor(file_inode(file)); |
494c2ebf | 177 | struct cpuinfo_x86 *c; |
1da177e4 | 178 | |
c903f045 AC |
179 | if (!capable(CAP_SYS_RAWIO)) |
180 | return -EPERM; | |
181 | ||
d6c30405 FW |
182 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
183 | return -ENXIO; /* No such CPU */ | |
184 | ||
5119e92e JC |
185 | c = &cpu_data(cpu); |
186 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
d6c30405 FW |
187 | return -EIO; /* MSR not supported */ |
188 | ||
189 | return 0; | |
1da177e4 LT |
190 | } |
191 | ||
192 | /* | |
193 | * File operations we support | |
194 | */ | |
5dfe4c96 | 195 | static const struct file_operations msr_fops = { |
1da177e4 LT |
196 | .owner = THIS_MODULE, |
197 | .llseek = msr_seek, | |
198 | .read = msr_read, | |
199 | .write = msr_write, | |
200 | .open = msr_open, | |
ff55df53 PA |
201 | .unlocked_ioctl = msr_ioctl, |
202 | .compat_ioctl = msr_ioctl, | |
1da177e4 LT |
203 | }; |
204 | ||
148f9bb8 | 205 | static int msr_device_create(int cpu) |
1da177e4 | 206 | { |
a271aaf1 | 207 | struct device *dev; |
1da177e4 | 208 | |
a9b12619 GKH |
209 | dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, |
210 | "msr%d", cpu); | |
cba0fdbc | 211 | return PTR_ERR_OR_ZERO(dev); |
881a841f AM |
212 | } |
213 | ||
214 | static void msr_device_destroy(int cpu) | |
215 | { | |
216 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
1da177e4 LT |
217 | } |
218 | ||
148f9bb8 PG |
219 | static int msr_class_cpu_callback(struct notifier_block *nfb, |
220 | unsigned long action, void *hcpu) | |
1da177e4 LT |
221 | { |
222 | unsigned int cpu = (unsigned long)hcpu; | |
881a841f | 223 | int err = 0; |
1da177e4 LT |
224 | |
225 | switch (action) { | |
881a841f | 226 | case CPU_UP_PREPARE: |
881a841f | 227 | err = msr_device_create(cpu); |
1da177e4 | 228 | break; |
881a841f | 229 | case CPU_UP_CANCELED: |
b844eba2 | 230 | case CPU_UP_CANCELED_FROZEN: |
1da177e4 | 231 | case CPU_DEAD: |
881a841f | 232 | msr_device_destroy(cpu); |
1da177e4 LT |
233 | break; |
234 | } | |
a94247e7 | 235 | return notifier_from_errno(err); |
1da177e4 LT |
236 | } |
237 | ||
c72258c7 | 238 | static struct notifier_block __refdata msr_class_cpu_notifier = { |
1da177e4 LT |
239 | .notifier_call = msr_class_cpu_callback, |
240 | }; | |
241 | ||
2c9ede55 | 242 | static char *msr_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
243 | { |
244 | return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); | |
245 | } | |
246 | ||
1da177e4 LT |
247 | static int __init msr_init(void) |
248 | { | |
249 | int i, err = 0; | |
250 | i = 0; | |
251 | ||
0b962d47 | 252 | if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { |
951a18c6 | 253 | pr_err("unable to get major %d for msr\n", MSR_MAJOR); |
1da177e4 LT |
254 | err = -EBUSY; |
255 | goto out; | |
256 | } | |
8874b414 | 257 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
258 | if (IS_ERR(msr_class)) { |
259 | err = PTR_ERR(msr_class); | |
260 | goto out_chrdev; | |
261 | } | |
e454cea2 | 262 | msr_class->devnode = msr_devnode; |
de82a01b SB |
263 | |
264 | cpu_notifier_register_begin(); | |
1da177e4 | 265 | for_each_online_cpu(i) { |
a271aaf1 | 266 | err = msr_device_create(i); |
1da177e4 LT |
267 | if (err != 0) |
268 | goto out_class; | |
269 | } | |
de82a01b SB |
270 | __register_hotcpu_notifier(&msr_class_cpu_notifier); |
271 | cpu_notifier_register_done(); | |
1da177e4 LT |
272 | |
273 | err = 0; | |
274 | goto out; | |
275 | ||
276 | out_class: | |
277 | i = 0; | |
278 | for_each_online_cpu(i) | |
881a841f | 279 | msr_device_destroy(i); |
de82a01b | 280 | cpu_notifier_register_done(); |
8874b414 | 281 | class_destroy(msr_class); |
1da177e4 | 282 | out_chrdev: |
0b962d47 | 283 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
1da177e4 LT |
284 | out: |
285 | return err; | |
286 | } | |
287 | ||
288 | static void __exit msr_exit(void) | |
289 | { | |
290 | int cpu = 0; | |
de82a01b SB |
291 | |
292 | cpu_notifier_register_begin(); | |
1da177e4 | 293 | for_each_online_cpu(cpu) |
881a841f | 294 | msr_device_destroy(cpu); |
8874b414 | 295 | class_destroy(msr_class); |
da482474 | 296 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
de82a01b SB |
297 | __unregister_hotcpu_notifier(&msr_class_cpu_notifier); |
298 | cpu_notifier_register_done(); | |
1da177e4 LT |
299 | } |
300 | ||
301 | module_init(msr_init); | |
302 | module_exit(msr_exit) | |
303 | ||
304 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
305 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
306 | MODULE_LICENSE("GPL"); |