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Commit | Line | Data |
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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; |
8fba38c9 | 47 | static enum cpuhp_state cpuhp_msr_state; |
1da177e4 | 48 | |
94a9fa41 PC |
49 | static ssize_t msr_read(struct file *file, char __user *buf, |
50 | size_t count, loff_t *ppos) | |
1da177e4 LT |
51 | { |
52 | u32 __user *tmp = (u32 __user *) buf; | |
53 | u32 data[2]; | |
1da177e4 | 54 | u32 reg = *ppos; |
6131ffaa | 55 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
56 | int err = 0; |
57 | ssize_t bytes = 0; | |
1da177e4 LT |
58 | |
59 | if (count % 8) | |
60 | return -EINVAL; /* Invalid chunk size */ | |
61 | ||
6926d570 | 62 | for (; count; count -= 8) { |
78a62d2c | 63 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
0cc0213e | 64 | if (err) |
85f1cb60 | 65 | break; |
85f1cb60 PA |
66 | if (copy_to_user(tmp, &data, 8)) { |
67 | err = -EFAULT; | |
68 | break; | |
c6f31932 | 69 | } |
1da177e4 | 70 | tmp += 2; |
85f1cb60 | 71 | bytes += 8; |
1da177e4 LT |
72 | } |
73 | ||
85f1cb60 | 74 | return bytes ? bytes : err; |
1da177e4 LT |
75 | } |
76 | ||
77 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
78 | size_t count, loff_t *ppos) | |
79 | { | |
80 | const u32 __user *tmp = (const u32 __user *)buf; | |
81 | u32 data[2]; | |
1da177e4 | 82 | u32 reg = *ppos; |
6131ffaa | 83 | int cpu = iminor(file_inode(file)); |
85f1cb60 PA |
84 | int err = 0; |
85 | ssize_t bytes = 0; | |
1da177e4 LT |
86 | |
87 | if (count % 8) | |
88 | return -EINVAL; /* Invalid chunk size */ | |
89 | ||
f475ff35 | 90 | for (; count; count -= 8) { |
85f1cb60 PA |
91 | if (copy_from_user(&data, tmp, 8)) { |
92 | err = -EFAULT; | |
93 | break; | |
94 | } | |
78a62d2c | 95 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
0cc0213e | 96 | if (err) |
85f1cb60 | 97 | break; |
1da177e4 | 98 | tmp += 2; |
85f1cb60 | 99 | bytes += 8; |
1da177e4 LT |
100 | } |
101 | ||
85f1cb60 | 102 | return bytes ? bytes : err; |
1da177e4 LT |
103 | } |
104 | ||
ff55df53 PA |
105 | static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) |
106 | { | |
107 | u32 __user *uregs = (u32 __user *)arg; | |
108 | u32 regs[8]; | |
6131ffaa | 109 | int cpu = iminor(file_inode(file)); |
ff55df53 PA |
110 | int err; |
111 | ||
112 | switch (ioc) { | |
113 | case X86_IOC_RDMSR_REGS: | |
114 | if (!(file->f_mode & FMODE_READ)) { | |
115 | err = -EBADF; | |
116 | break; | |
117 | } | |
118 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
119 | err = -EFAULT; | |
120 | break; | |
121 | } | |
122 | err = rdmsr_safe_regs_on_cpu(cpu, regs); | |
123 | if (err) | |
124 | break; | |
125 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
126 | err = -EFAULT; | |
127 | break; | |
128 | ||
129 | case X86_IOC_WRMSR_REGS: | |
130 | if (!(file->f_mode & FMODE_WRITE)) { | |
131 | err = -EBADF; | |
132 | break; | |
133 | } | |
134 | if (copy_from_user(®s, uregs, sizeof regs)) { | |
135 | err = -EFAULT; | |
136 | break; | |
137 | } | |
138 | err = wrmsr_safe_regs_on_cpu(cpu, regs); | |
139 | if (err) | |
140 | break; | |
141 | if (copy_to_user(uregs, ®s, sizeof regs)) | |
142 | err = -EFAULT; | |
143 | break; | |
144 | ||
145 | default: | |
146 | err = -ENOTTY; | |
147 | break; | |
148 | } | |
149 | ||
150 | return err; | |
151 | } | |
152 | ||
1da177e4 LT |
153 | static int msr_open(struct inode *inode, struct file *file) |
154 | { | |
6131ffaa | 155 | unsigned int cpu = iminor(file_inode(file)); |
494c2ebf | 156 | struct cpuinfo_x86 *c; |
1da177e4 | 157 | |
c903f045 AC |
158 | if (!capable(CAP_SYS_RAWIO)) |
159 | return -EPERM; | |
160 | ||
d6c30405 FW |
161 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
162 | return -ENXIO; /* No such CPU */ | |
163 | ||
5119e92e JC |
164 | c = &cpu_data(cpu); |
165 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
d6c30405 FW |
166 | return -EIO; /* MSR not supported */ |
167 | ||
168 | return 0; | |
1da177e4 LT |
169 | } |
170 | ||
171 | /* | |
172 | * File operations we support | |
173 | */ | |
5dfe4c96 | 174 | static const struct file_operations msr_fops = { |
1da177e4 | 175 | .owner = THIS_MODULE, |
b25472f9 | 176 | .llseek = no_seek_end_llseek, |
1da177e4 LT |
177 | .read = msr_read, |
178 | .write = msr_write, | |
179 | .open = msr_open, | |
ff55df53 PA |
180 | .unlocked_ioctl = msr_ioctl, |
181 | .compat_ioctl = msr_ioctl, | |
1da177e4 LT |
182 | }; |
183 | ||
8fba38c9 | 184 | static int msr_device_create(unsigned int cpu) |
1da177e4 | 185 | { |
a271aaf1 | 186 | struct device *dev; |
1da177e4 | 187 | |
a9b12619 GKH |
188 | dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, |
189 | "msr%d", cpu); | |
cba0fdbc | 190 | return PTR_ERR_OR_ZERO(dev); |
881a841f AM |
191 | } |
192 | ||
8fba38c9 | 193 | static int msr_device_destroy(unsigned int cpu) |
881a841f AM |
194 | { |
195 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
8fba38c9 | 196 | return 0; |
1da177e4 LT |
197 | } |
198 | ||
2c9ede55 | 199 | static char *msr_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
200 | { |
201 | return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); | |
202 | } | |
203 | ||
1da177e4 LT |
204 | static int __init msr_init(void) |
205 | { | |
8fba38c9 | 206 | int err; |
1da177e4 | 207 | |
0b962d47 | 208 | if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { |
951a18c6 | 209 | pr_err("unable to get major %d for msr\n", MSR_MAJOR); |
8fba38c9 | 210 | return -EBUSY; |
1da177e4 | 211 | } |
8874b414 | 212 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
213 | if (IS_ERR(msr_class)) { |
214 | err = PTR_ERR(msr_class); | |
215 | goto out_chrdev; | |
216 | } | |
e454cea2 | 217 | msr_class->devnode = msr_devnode; |
de82a01b | 218 | |
8fba38c9 SAS |
219 | err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online", |
220 | msr_device_create, msr_device_destroy); | |
221 | if (err < 0) | |
222 | goto out_class; | |
223 | cpuhp_msr_state = err; | |
224 | return 0; | |
1da177e4 LT |
225 | |
226 | out_class: | |
8fba38c9 | 227 | cpuhp_remove_state(cpuhp_msr_state); |
8874b414 | 228 | class_destroy(msr_class); |
1da177e4 | 229 | out_chrdev: |
0b962d47 | 230 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
1da177e4 LT |
231 | return err; |
232 | } | |
8fba38c9 | 233 | module_init(msr_init); |
1da177e4 LT |
234 | |
235 | static void __exit msr_exit(void) | |
236 | { | |
8fba38c9 | 237 | cpuhp_remove_state(cpuhp_msr_state); |
8874b414 | 238 | class_destroy(msr_class); |
da482474 | 239 | __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); |
1da177e4 | 240 | } |
1da177e4 LT |
241 | module_exit(msr_exit) |
242 | ||
243 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
244 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
245 | MODULE_LICENSE("GPL"); |