![Rafael J. Wysocki](/assets/img/avatar_default.png)
Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
225 lines
4.9 KiB
C
225 lines
4.9 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2000 H. Peter Anvin - All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
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* USA; either version 2 of the License, or (at your option) any later
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* version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* msr.c
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*
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* x86 MSR access device
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*
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* This device is accessed by lseek() to the appropriate register number
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* and then read/write in chunks of 8 bytes. A larger size means multiple
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* reads or writes of the same register.
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*
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* This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
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* an SMP box will direct the access to CPU %d.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/init.h>
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#include <linux/poll.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/major.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <asm/processor.h>
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#include <asm/msr.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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static struct class *msr_class;
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static loff_t msr_seek(struct file *file, loff_t offset, int orig)
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{
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loff_t ret = -EINVAL;
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lock_kernel();
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switch (orig) {
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case 0:
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file->f_pos = offset;
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ret = file->f_pos;
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break;
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case 1:
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file->f_pos += offset;
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ret = file->f_pos;
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}
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unlock_kernel();
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return ret;
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}
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static ssize_t msr_read(struct file *file, char __user * buf,
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size_t count, loff_t * ppos)
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{
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u32 __user *tmp = (u32 __user *) buf;
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u32 data[2];
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u32 reg = *ppos;
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int cpu = iminor(file->f_path.dentry->d_inode);
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int err;
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if (count % 8)
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return -EINVAL; /* Invalid chunk size */
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for (; count; count -= 8) {
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err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
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if (err)
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return -EIO;
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if (copy_to_user(tmp, &data, 8))
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return -EFAULT;
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tmp += 2;
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}
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return ((char __user *)tmp) - buf;
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}
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static ssize_t msr_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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const u32 __user *tmp = (const u32 __user *)buf;
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u32 data[2];
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u32 reg = *ppos;
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int cpu = iminor(file->f_path.dentry->d_inode);
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int err;
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if (count % 8)
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return -EINVAL; /* Invalid chunk size */
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for (; count; count -= 8) {
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if (copy_from_user(&data, tmp, 8))
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return -EFAULT;
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err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
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if (err)
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return -EIO;
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tmp += 2;
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}
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return ((char __user *)tmp) - buf;
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}
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static int msr_open(struct inode *inode, struct file *file)
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{
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unsigned int cpu = iminor(file->f_path.dentry->d_inode);
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struct cpuinfo_x86 *c = &(cpu_data)[cpu];
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if (cpu >= NR_CPUS || !cpu_online(cpu))
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return -ENXIO; /* No such CPU */
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if (!cpu_has(c, X86_FEATURE_MSR))
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return -EIO; /* MSR not supported */
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return 0;
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}
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/*
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* File operations we support
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*/
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static const struct file_operations msr_fops = {
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.owner = THIS_MODULE,
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.llseek = msr_seek,
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.read = msr_read,
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.write = msr_write,
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.open = msr_open,
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};
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static int msr_device_create(int i)
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{
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int err = 0;
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struct device *dev;
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dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, i), "msr%d",i);
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if (IS_ERR(dev))
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err = PTR_ERR(dev);
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return err;
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}
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static int msr_class_cpu_callback(struct notifier_block *nfb,
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unsigned long action, void *hcpu)
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{
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unsigned int cpu = (unsigned long)hcpu;
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switch (action) {
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case CPU_ONLINE:
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case CPU_ONLINE_FROZEN:
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msr_device_create(cpu);
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break;
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block __cpuinitdata msr_class_cpu_notifier =
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{
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.notifier_call = msr_class_cpu_callback,
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};
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static int __init msr_init(void)
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{
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int i, err = 0;
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i = 0;
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if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
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printk(KERN_ERR "msr: unable to get major %d for msr\n",
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MSR_MAJOR);
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err = -EBUSY;
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goto out;
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}
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msr_class = class_create(THIS_MODULE, "msr");
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if (IS_ERR(msr_class)) {
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err = PTR_ERR(msr_class);
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goto out_chrdev;
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}
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for_each_online_cpu(i) {
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err = msr_device_create(i);
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if (err != 0)
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goto out_class;
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}
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register_hotcpu_notifier(&msr_class_cpu_notifier);
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err = 0;
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goto out;
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out_class:
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i = 0;
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for_each_online_cpu(i)
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device_destroy(msr_class, MKDEV(MSR_MAJOR, i));
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class_destroy(msr_class);
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out_chrdev:
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unregister_chrdev(MSR_MAJOR, "cpu/msr");
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out:
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return err;
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}
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static void __exit msr_exit(void)
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{
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int cpu = 0;
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for_each_online_cpu(cpu)
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device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
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class_destroy(msr_class);
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unregister_chrdev(MSR_MAJOR, "cpu/msr");
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unregister_hotcpu_notifier(&msr_class_cpu_notifier);
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}
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module_init(msr_init);
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module_exit(msr_exit)
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MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
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MODULE_DESCRIPTION("x86 generic MSR driver");
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MODULE_LICENSE("GPL");
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