/* ----------------------------------------------------------------------- * * * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved * Copyright 2009 Intel Corporation; author: H. Peter Anvin * * 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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_inode(file); mutex_lock(&inode->i_mutex); switch (orig) { case SEEK_SET: file->f_pos = offset; ret = file->f_pos; break; case SEEK_CUR: 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_inode(file)); int err = 0; ssize_t bytes = 0; 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) break; if (copy_to_user(tmp, &data, 8)) { err = -EFAULT; break; } tmp += 2; bytes += 8; } return bytes ? bytes : err; } 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_inode(file)); int err = 0; ssize_t bytes = 0; if (count % 8) return -EINVAL; /* Invalid chunk size */ for (; count; count -= 8) { if (copy_from_user(&data, tmp, 8)) { err = -EFAULT; break; } err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); if (err) break; tmp += 2; bytes += 8; } return bytes ? bytes : err; } static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) { u32 __user *uregs = (u32 __user *)arg; u32 regs[8]; int cpu = iminor(file_inode(file)); int err; switch (ioc) { case X86_IOC_RDMSR_REGS: if (!(file->f_mode & FMODE_READ)) { err = -EBADF; break; } if (copy_from_user(®s, uregs, sizeof regs)) { err = -EFAULT; break; } err = rdmsr_safe_regs_on_cpu(cpu, regs); if (err) break; if (copy_to_user(uregs, ®s, sizeof regs)) err = -EFAULT; break; case X86_IOC_WRMSR_REGS: if (!(file->f_mode & FMODE_WRITE)) { err = -EBADF; break; } if (copy_from_user(®s, uregs, sizeof regs)) { err = -EFAULT; break; } err = wrmsr_safe_regs_on_cpu(cpu, regs); if (err) break; if (copy_to_user(uregs, ®s, sizeof regs)) err = -EFAULT; break; default: err = -ENOTTY; break; } return err; } static int msr_open(struct inode *inode, struct file *file) { unsigned int cpu = iminor(file_inode(file)); struct cpuinfo_x86 *c; if (!capable(CAP_SYS_RAWIO)) return -EPERM; if (cpu >= nr_cpu_ids || !cpu_online(cpu)) return -ENXIO; /* No such CPU */ c = &cpu_data(cpu); if (!cpu_has(c, X86_FEATURE_MSR)) return -EIO; /* MSR not supported */ return 0; } /* * 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, .unlocked_ioctl = msr_ioctl, .compat_ioctl = msr_ioctl, }; static int msr_device_create(int cpu) { struct device *dev; dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, "msr%d", cpu); return PTR_ERR_OR_ZERO(dev); } static void msr_device_destroy(int cpu) { device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); } static int 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 notifier_from_errno(err); } static struct notifier_block __refdata msr_class_cpu_notifier = { .notifier_call = msr_class_cpu_callback, }; static char *msr_devnode(struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); } static int __init msr_init(void) { int i, err = 0; i = 0; if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { pr_err("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; } msr_class->devnode = msr_devnode; cpu_notifier_register_begin(); for_each_online_cpu(i) { err = msr_device_create(i); if (err != 0) goto out_class; } __register_hotcpu_notifier(&msr_class_cpu_notifier); cpu_notifier_register_done(); err = 0; goto out; out_class: i = 0; for_each_online_cpu(i) msr_device_destroy(i); cpu_notifier_register_done(); class_destroy(msr_class); out_chrdev: __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); out: return err; } static void __exit msr_exit(void) { int cpu = 0; cpu_notifier_register_begin(); for_each_online_cpu(cpu) msr_device_destroy(cpu); class_destroy(msr_class); __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); __unregister_hotcpu_notifier(&msr_class_cpu_notifier); cpu_notifier_register_done(); } module_init(msr_init); module_exit(msr_exit) MODULE_AUTHOR("H. Peter Anvin "); MODULE_DESCRIPTION("x86 generic MSR driver"); MODULE_LICENSE("GPL");