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 | 42 | |
cd4d09ec | 43 | #include <asm/cpufeature.h> |
1da177e4 | 44 | #include <asm/msr.h> |
1da177e4 | 45 | |
8874b414 | 46 | static struct class *msr_class; |
1da177e4 | 47 | |
94a9fa41 PC |
48 | static ssize_t msr_read(struct file *file, char __user *buf, |
49 | size_t count, loff_t *ppos) | |
1da177e4 LT |
50 | { |
51 | u32 __user *tmp = (u32 __user *) buf; | |
52 | u32 data[2]; | |
1da177e4 | 53 | u32 reg = *ppos; |
6131ffaa | 54 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
55 | int err = 0; |
56 | ssize_t bytes = 0; | |
1da177e4 LT |
57 | |
58 | if (count % 8) | |
59 | return -EINVAL; /* Invalid chunk size */ | |
60 | ||
6926d570 | 61 | for (; count; count -= 8) { |
78a62d2c | 62 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
0cc0213e | 63 | if (err) |
85f1cb60 | 64 | break; |
85f1cb60 PA |
65 | if (copy_to_user(tmp, &data, 8)) { |
66 | err = -EFAULT; | |
67 | break; | |
c6f31932 | 68 | } |
1da177e4 | 69 | tmp += 2; |
85f1cb60 | 70 | bytes += 8; |
1da177e4 LT |
71 | } |
72 | ||
85f1cb60 | 73 | return bytes ? bytes : err; |
1da177e4 LT |
74 | } |
75 | ||
76 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
77 | size_t count, loff_t *ppos) | |
78 | { | |
79 | const u32 __user *tmp = (const u32 __user *)buf; | |
80 | u32 data[2]; | |
1da177e4 | 81 | u32 reg = *ppos; |
6131ffaa | 82 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
83 | int err = 0; |
84 | ssize_t bytes = 0; | |
1da177e4 LT |
85 | |
86 | if (count % 8) | |
87 | return -EINVAL; /* Invalid chunk size */ | |
88 | ||
f475ff35 | 89 | for (; count; count -= 8) { |
85f1cb60 PA |
90 | if (copy_from_user(&data, tmp, 8)) { |
91 | err = -EFAULT; | |
92 | break; | |
93 | } | |
78a62d2c | 94 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
0cc0213e | 95 | if (err) |
85f1cb60 | 96 | break; |
1da177e4 | 97 | tmp += 2; |
85f1cb60 | 98 | bytes += 8; |
1da177e4 LT |
99 | } |
100 | ||
85f1cb60 | 101 | return bytes ? bytes : err; |
1da177e4 LT |
102 | } |
103 | ||
ff55df53 PA |
104 | static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) |
105 | { | |
106 | u32 __user *uregs = (u32 __user *)arg; | |
107 | u32 regs[8]; | |
6131ffaa | 108 | int cpu = iminor(file_inode(file)); |
ff55df53 PA |
109 | int err; |
110 | ||
111 | switch (ioc) { | |
112 | case X86_IOC_RDMSR_REGS: | |
113 | if (!(file->f_mode & FMODE_READ)) { | |
114 | err = -EBADF; | |
115 | break; | |
116 | } | |
117 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
118 | err = -EFAULT; | |
119 | break; | |
120 | } | |
121 | err = rdmsr_safe_regs_on_cpu(cpu, regs); | |
122 | if (err) | |
123 | break; | |
124 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
125 | err = -EFAULT; | |
126 | break; | |
127 | ||
128 | case X86_IOC_WRMSR_REGS: | |
129 | if (!(file->f_mode & FMODE_WRITE)) { | |
130 | err = -EBADF; | |
131 | break; | |
132 | } | |
133 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
134 | err = -EFAULT; | |
135 | break; | |
136 | } | |
137 | err = wrmsr_safe_regs_on_cpu(cpu, regs); | |
138 | if (err) | |
139 | break; | |
140 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
141 | err = -EFAULT; | |
142 | break; | |
143 | ||
144 | default: | |
145 | err = -ENOTTY; | |
146 | break; | |
147 | } | |
148 | ||
149 | return err; | |
150 | } | |
151 | ||
1da177e4 LT |
152 | static int msr_open(struct inode *inode, struct file *file) |
153 | { | |
6131ffaa | 154 | unsigned int cpu = iminor(file_inode(file)); |
494c2ebf | 155 | struct cpuinfo_x86 *c; |
1da177e4 | 156 | |
c903f045 AC |
157 | if (!capable(CAP_SYS_RAWIO)) |
158 | return -EPERM; | |
159 | ||
d6c30405 FW |
160 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
161 | return -ENXIO; /* No such CPU */ | |
162 | ||
5119e92e JC |
163 | c = &cpu_data(cpu); |
164 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
d6c30405 FW |
165 | return -EIO; /* MSR not supported */ |
166 | ||
167 | return 0; | |
1da177e4 LT |
168 | } |
169 | ||
170 | /* | |
171 | * File operations we support | |
172 | */ | |
5dfe4c96 | 173 | static const struct file_operations msr_fops = { |
1da177e4 | 174 | .owner = THIS_MODULE, |
b25472f9 | 175 | .llseek = no_seek_end_llseek, |
1da177e4 LT |
176 | .read = msr_read, |
177 | .write = msr_write, | |
178 | .open = msr_open, | |
ff55df53 PA |
179 | .unlocked_ioctl = msr_ioctl, |
180 | .compat_ioctl = msr_ioctl, | |
1da177e4 LT |
181 | }; |
182 | ||
148f9bb8 | 183 | static int msr_device_create(int cpu) |
1da177e4 | 184 | { |
a271aaf1 | 185 | struct device *dev; |
1da177e4 | 186 | |
a9b12619 GKH |
187 | dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, |
188 | "msr%d", cpu); | |
cba0fdbc | 189 | return PTR_ERR_OR_ZERO(dev); |
881a841f AM |
190 | } |
191 | ||
192 | static void msr_device_destroy(int cpu) | |
193 | { | |
194 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
1da177e4 LT |
195 | } |
196 | ||
148f9bb8 PG |
197 | static int msr_class_cpu_callback(struct notifier_block *nfb, |
198 | unsigned long action, void *hcpu) | |
1da177e4 LT |
199 | { |
200 | unsigned int cpu = (unsigned long)hcpu; | |
881a841f | 201 | int err = 0; |
1da177e4 LT |
202 | |
203 | switch (action) { | |
881a841f | 204 | case CPU_UP_PREPARE: |
881a841f | 205 | err = msr_device_create(cpu); |
1da177e4 | 206 | break; |
881a841f | 207 | case CPU_UP_CANCELED: |
b844eba2 | 208 | case CPU_UP_CANCELED_FROZEN: |
1da177e4 | 209 | case CPU_DEAD: |
881a841f | 210 | msr_device_destroy(cpu); |
1da177e4 LT |
211 | break; |
212 | } | |
a94247e7 | 213 | return notifier_from_errno(err); |
1da177e4 LT |
214 | } |
215 | ||
c72258c7 | 216 | static struct notifier_block __refdata msr_class_cpu_notifier = { |
1da177e4 LT |
217 | .notifier_call = msr_class_cpu_callback, |
218 | }; | |
219 | ||
2c9ede55 | 220 | static char *msr_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
221 | { |
222 | return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); | |
223 | } | |
224 | ||
1da177e4 LT |
225 | static int __init msr_init(void) |
226 | { | |
227 | int i, err = 0; | |
228 | i = 0; | |
229 | ||
0b962d47 | 230 | if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { |
951a18c6 | 231 | pr_err("unable to get major %d for msr\n", MSR_MAJOR); |
1da177e4 LT |
232 | err = -EBUSY; |
233 | goto out; | |
234 | } | |
8874b414 | 235 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
236 | if (IS_ERR(msr_class)) { |
237 | err = PTR_ERR(msr_class); | |
238 | goto out_chrdev; | |
239 | } | |
e454cea2 | 240 | msr_class->devnode = msr_devnode; |
de82a01b SB |
241 | |
242 | cpu_notifier_register_begin(); | |
1da177e4 | 243 | for_each_online_cpu(i) { |
a271aaf1 | 244 | err = msr_device_create(i); |
1da177e4 LT |
245 | if (err != 0) |
246 | goto out_class; | |
247 | } | |
de82a01b SB |
248 | __register_hotcpu_notifier(&msr_class_cpu_notifier); |
249 | cpu_notifier_register_done(); | |
1da177e4 LT |
250 | |
251 | err = 0; | |
252 | goto out; | |
253 | ||
254 | out_class: | |
255 | i = 0; | |
256 | for_each_online_cpu(i) | |
881a841f | 257 | msr_device_destroy(i); |
de82a01b | 258 | cpu_notifier_register_done(); |
8874b414 | 259 | class_destroy(msr_class); |
1da177e4 | 260 | out_chrdev: |
0b962d47 | 261 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
1da177e4 LT |
262 | out: |
263 | return err; | |
264 | } | |
265 | ||
266 | static void __exit msr_exit(void) | |
267 | { | |
268 | int cpu = 0; | |
de82a01b SB |
269 | |
270 | cpu_notifier_register_begin(); | |
1da177e4 | 271 | for_each_online_cpu(cpu) |
881a841f | 272 | msr_device_destroy(cpu); |
8874b414 | 273 | class_destroy(msr_class); |
da482474 | 274 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
de82a01b SB |
275 | __unregister_hotcpu_notifier(&msr_class_cpu_notifier); |
276 | cpu_notifier_register_done(); | |
1da177e4 LT |
277 | } |
278 | ||
279 | module_init(msr_init); | |
280 | module_exit(msr_exit) | |
281 | ||
282 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
283 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
284 | MODULE_LICENSE("GPL"); |