Initial import

1 files changed, 306 insertions, 0 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
new file mode 100644
index 000000000..113e70784
--- /dev/null
+++ b/arch/x86/kernel/msr.c
@@ -0,0 +1,306 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   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 <linux/module.h>
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/smp.h>
+#include <linux/major.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/uaccess.h>
+#include <linux/gfp.h>
+
+#include <asm/processor.h>
+#include <asm/msr.h>
+
+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(&regs, uregs, sizeof regs)) {
+			err = -EFAULT;
+			break;
+		}
+		err = rdmsr_safe_regs_on_cpu(cpu, regs);
+		if (err)
+			break;
+		if (copy_to_user(uregs, &regs, sizeof regs))
+			err = -EFAULT;
+		break;
+
+	case X86_IOC_WRMSR_REGS:
+		if (!(file->f_mode & FMODE_WRITE)) {
+			err = -EBADF;
+			break;
+		}
+		if (copy_from_user(&regs, uregs, sizeof regs)) {
+			err = -EFAULT;
+			break;
+		}
+		err = wrmsr_safe_regs_on_cpu(cpu, regs);
+		if (err)
+			break;
+		if (copy_to_user(uregs, &regs, 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 <hpa@zytor.com>");
+MODULE_DESCRIPTION("x86 generic MSR driver");
+MODULE_LICENSE("GPL");