arch/x86/kernel/microcode_core.c - linux/kernel/git/klassert/ipsec - Git at Google

 /*
  *	Intel CPU Microcode Update Driver for Linux
  *
  *	Copyright (C) 2000-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
  *		      2006	Shaohua Li <shaohua.li@intel.com>
  *
  *	This driver allows to upgrade microcode on Intel processors
  *	belonging to IA-32 family - PentiumPro, Pentium II,
  *	Pentium III, Xeon, Pentium 4, etc.
  *
  *	Reference: Section 8.11 of Volume 3a, IA-32 Intel? Architecture
  *	Software Developer's Manual
  *	Order Number 253668 or free download from:
  *
  *	http://developer.intel.com/Assets/PDF/manual/253668.pdf
  *
  *	For more information, go to http://www.urbanmyth.org/microcode
  *
  *	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; either version
  *	2 of the License, or (at your option) any later version.
  *
  *	1.0	16 Feb 2000, Tigran Aivazian <tigran@sco.com>
  *		Initial release.
  *	1.01	18 Feb 2000, Tigran Aivazian <tigran@sco.com>
  *		Added read() support + cleanups.
  *	1.02	21 Feb 2000, Tigran Aivazian <tigran@sco.com>
  *		Added 'device trimming' support. open(O_WRONLY) zeroes
  *		and frees the saved copy of applied microcode.
  *	1.03	29 Feb 2000, Tigran Aivazian <tigran@sco.com>
  *		Made to use devfs (/dev/cpu/microcode) + cleanups.
  *	1.04	06 Jun 2000, Simon Trimmer <simon@veritas.com>
  *		Added misc device support (now uses both devfs and misc).
  *		Added MICROCODE_IOCFREE ioctl to clear memory.
  *	1.05	09 Jun 2000, Simon Trimmer <simon@veritas.com>
  *		Messages for error cases (non Intel & no suitable microcode).
  *	1.06	03 Aug 2000, Tigran Aivazian <tigran@veritas.com>
  *		Removed ->release(). Removed exclusive open and status bitmap.
  *		Added microcode_rwsem to serialize read()/write()/ioctl().
  *		Removed global kernel lock usage.
  *	1.07	07 Sep 2000, Tigran Aivazian <tigran@veritas.com>
  *		Write 0 to 0x8B msr and then cpuid before reading revision,
  *		so that it works even if there were no update done by the
  *		BIOS. Otherwise, reading from 0x8B gives junk (which happened
  *		to be 0 on my machine which is why it worked even when I
  *		disabled update by the BIOS)
  *		Thanks to Eric W. Biederman <ebiederman@lnxi.com> for the fix.
  *	1.08	11 Dec 2000, Richard Schaal <richard.schaal@intel.com> and
  *			     Tigran Aivazian <tigran@veritas.com>
  *		Intel Pentium 4 processor support and bugfixes.
  *	1.09	30 Oct 2001, Tigran Aivazian <tigran@veritas.com>
  *		Bugfix for HT (Hyper-Threading) enabled processors
  *		whereby processor resources are shared by all logical processors
  *		in a single CPU package.
  *	1.10	28 Feb 2002 Asit K Mallick <asit.k.mallick@intel.com> and
  *		Tigran Aivazian <tigran@veritas.com>,
  *		Serialize updates as required on HT processors due to
  *		speculative nature of implementation.
  *	1.11	22 Mar 2002 Tigran Aivazian <tigran@veritas.com>
  *		Fix the panic when writing zero-length microcode chunk.
  *	1.12	29 Sep 2003 Nitin Kamble <nitin.a.kamble@intel.com>,
  *		Jun Nakajima <jun.nakajima@intel.com>
  *		Support for the microcode updates in the new format.
  *	1.13	10 Oct 2003 Tigran Aivazian <tigran@veritas.com>
  *		Removed ->read() method and obsoleted MICROCODE_IOCFREE ioctl
  *		because we no longer hold a copy of applied microcode
  *		in kernel memory.
  *	1.14	25 Jun 2004 Tigran Aivazian <tigran@veritas.com>
  *		Fix sigmatch() macro to handle old CPUs with pf == 0.
  *		Thanks to Stuart Swales for pointing out this bug.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/platform_device.h>
 #include <linux/miscdevice.h>
 #include <linux/capability.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/cpu.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/syscore_ops.h>

 #include <asm/microcode.h>
 #include <asm/processor.h>
 #include <asm/cpu_device_id.h>
 #include <asm/perf_event.h>

 MODULE_DESCRIPTION("Microcode Update Driver");
 MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");
 MODULE_LICENSE("GPL");

 #define MICROCODE_VERSION	"2.00"

 static struct microcode_ops	*microcode_ops;

 /*
  * Synchronization.
  *
  * All non cpu-hotplug-callback call sites use:
  *
  * - microcode_mutex to synchronize with each other;
  * - get/put_online_cpus() to synchronize with
  *   the cpu-hotplug-callback call sites.
  *
  * We guarantee that only a single cpu is being
  * updated at any particular moment of time.
  */
 static DEFINE_MUTEX(microcode_mutex);

 struct ucode_cpu_info		ucode_cpu_info[NR_CPUS];
 EXPORT_SYMBOL_GPL(ucode_cpu_info);

 /*
  * Operations that are run on a target cpu:
  */

 struct cpu_info_ctx {
 	struct cpu_signature	*cpu_sig;
 	int			err;
 };

 static void collect_cpu_info_local(void *arg)
 {
 	struct cpu_info_ctx *ctx = arg;

 	ctx->err = microcode_ops->collect_cpu_info(smp_processor_id(),
 						   ctx->cpu_sig);
 }

 static int collect_cpu_info_on_target(int cpu, struct cpu_signature *cpu_sig)
 {
 	struct cpu_info_ctx ctx = { .cpu_sig = cpu_sig, .err = 0 };
 	int ret;

 	ret = smp_call_function_single(cpu, collect_cpu_info_local, &ctx, 1);
 	if (!ret)
 		ret = ctx.err;

 	return ret;
 }

 static int collect_cpu_info(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	int ret;

 	memset(uci, 0, sizeof(*uci));

 	ret = collect_cpu_info_on_target(cpu, &uci->cpu_sig);
 	if (!ret)
 		uci->valid = 1;

 	return ret;
 }

 struct apply_microcode_ctx {
 	int err;
 };

 static void apply_microcode_local(void *arg)
 {
 	struct apply_microcode_ctx *ctx = arg;

 	ctx->err = microcode_ops->apply_microcode(smp_processor_id());
 }

 static int apply_microcode_on_target(int cpu)
 {
 	struct apply_microcode_ctx ctx = { .err = 0 };
 	int ret;

 	ret = smp_call_function_single(cpu, apply_microcode_local, &ctx, 1);
 	if (!ret)
 		ret = ctx.err;

 	return ret;
 }

 #ifdef CONFIG_MICROCODE_OLD_INTERFACE
 static int do_microcode_update(const void __user *buf, size_t size)
 {
 	int error = 0;
 	int cpu;

 	for_each_online_cpu(cpu) {
 		struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 		enum ucode_state ustate;

 		if (!uci->valid)
 			continue;

 		ustate = microcode_ops->request_microcode_user(cpu, buf, size);
 		if (ustate == UCODE_ERROR) {
 			error = -1;
 			break;
 		} else if (ustate == UCODE_OK)
 			apply_microcode_on_target(cpu);
 	}

 	return error;
 }

 static int microcode_open(struct inode *inode, struct file *file)
 {
 	return capable(CAP_SYS_RAWIO) ? nonseekable_open(inode, file) : -EPERM;
 }

 static ssize_t microcode_write(struct file *file, const char __user *buf,
 			       size_t len, loff_t *ppos)
 {
 	ssize_t ret = -EINVAL;

 	if ((len >> PAGE_SHIFT) > totalram_pages) {
 		pr_err("too much data (max %ld pages)\n", totalram_pages);
 		return ret;
 	}

 	get_online_cpus();
 	mutex_lock(&microcode_mutex);

 	if (do_microcode_update(buf, len) == 0)
 		ret = (ssize_t)len;

 	if (ret > 0)
 		perf_check_microcode();

 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();

 	return ret;
 }

 static const struct file_operations microcode_fops = {
 	.owner			= THIS_MODULE,
 	.write			= microcode_write,
 	.open			= microcode_open,
 	.llseek		= no_llseek,
 };

 static struct miscdevice microcode_dev = {
 	.minor			= MICROCODE_MINOR,
 	.name			= "microcode",
 	.nodename		= "cpu/microcode",
 	.fops			= &microcode_fops,
 };

 static int __init microcode_dev_init(void)
 {
 	int error;

 	error = misc_register(&microcode_dev);
 	if (error) {
 		pr_err("can't misc_register on minor=%d\n", MICROCODE_MINOR);
 		return error;
 	}

 	return 0;
 }

 static void __exit microcode_dev_exit(void)
 {
 	misc_deregister(&microcode_dev);
 }

 MODULE_ALIAS_MISCDEV(MICROCODE_MINOR);
 MODULE_ALIAS("devname:cpu/microcode");
 #else
 #define microcode_dev_init()	0
 #define microcode_dev_exit()	do { } while (0)
 #endif

 /* fake device for request_firmware */
 static struct platform_device	*microcode_pdev;

 static int reload_for_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	int err = 0;

 	if (uci->valid) {
 		enum ucode_state ustate;

 		ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev);
 		if (ustate == UCODE_OK)
 			apply_microcode_on_target(cpu);
 		else
 			if (ustate == UCODE_ERROR)
 				err = -EINVAL;
 	}

 	return err;
 }

 static ssize_t reload_store(struct device *dev,
 			    struct device_attribute *attr,
 			    const char *buf, size_t size)
 {
 	unsigned long val;
 	int cpu;
 	ssize_t ret = 0, tmp_ret;

 	ret = kstrtoul(buf, 0, &val);
 	if (ret)
 		return ret;

 	if (val != 1)
 		return size;

 	get_online_cpus();
 	mutex_lock(&microcode_mutex);
 	for_each_online_cpu(cpu) {
 		tmp_ret = reload_for_cpu(cpu);
 		if (tmp_ret != 0)
 			pr_warn("Error reloading microcode on CPU %d\n", cpu);

 		/* save retval of the first encountered reload error */
 		if (!ret)
 			ret = tmp_ret;
 	}
 	if (!ret)
 		perf_check_microcode();
 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();

 	if (!ret)
 		ret = size;

 	return ret;
 }

 static ssize_t version_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

 	return sprintf(buf, "0x%x\n", uci->cpu_sig.rev);
 }

 static ssize_t pf_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

 	return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
 }

 static DEVICE_ATTR(reload, 0200, NULL, reload_store);
 static DEVICE_ATTR(version, 0400, version_show, NULL);
 static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);

 static struct attribute *mc_default_attrs[] = {
 	&dev_attr_version.attr,
 	&dev_attr_processor_flags.attr,
 	NULL
 };

 static struct attribute_group mc_attr_group = {
 	.attrs			= mc_default_attrs,
 	.name			= "microcode",
 };

 static void microcode_fini_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

 	microcode_ops->microcode_fini_cpu(cpu);
 	uci->valid = 0;
 }

 static enum ucode_state microcode_resume_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

 	if (!uci->mc)
 		return UCODE_NFOUND;

 	pr_debug("CPU%d updated upon resume\n", cpu);
 	apply_microcode_on_target(cpu);

 	return UCODE_OK;
 }

 static enum ucode_state microcode_init_cpu(int cpu)
 {
 	enum ucode_state ustate;

 	if (collect_cpu_info(cpu))
 		return UCODE_ERROR;

 	/* --dimm. Trigger a delayed update? */
 	if (system_state != SYSTEM_RUNNING)
 		return UCODE_NFOUND;

 	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev);

 	if (ustate == UCODE_OK) {
 		pr_debug("CPU%d updated upon init\n", cpu);
 		apply_microcode_on_target(cpu);
 	}

 	return ustate;
 }

 static enum ucode_state microcode_update_cpu(int cpu)
 {
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	enum ucode_state ustate;

 	if (uci->valid)
 		ustate = microcode_resume_cpu(cpu);
 	else
 		ustate = microcode_init_cpu(cpu);

 	return ustate;
 }

 static int mc_device_add(struct device *dev, struct subsys_interface *sif)
 {
 	int err, cpu = dev->id;

 	if (!cpu_online(cpu))
 		return 0;

 	pr_debug("CPU%d added\n", cpu);

 	err = sysfs_create_group(&dev->kobj, &mc_attr_group);
 	if (err)
 		return err;

 	if (microcode_init_cpu(cpu) == UCODE_ERROR)
 		return -EINVAL;

 	return err;
 }

 static int mc_device_remove(struct device *dev, struct subsys_interface *sif)
 {
 	int cpu = dev->id;

 	if (!cpu_online(cpu))
 		return 0;

 	pr_debug("CPU%d removed\n", cpu);
 	microcode_fini_cpu(cpu);
 	sysfs_remove_group(&dev->kobj, &mc_attr_group);
 	return 0;
 }

 static struct subsys_interface mc_cpu_interface = {
 	.name			= "microcode",
 	.subsys			= &cpu_subsys,
 	.add_dev		= mc_device_add,
 	.remove_dev		= mc_device_remove,
 };

 /**
  * mc_bp_resume - Update boot CPU microcode during resume.
  */
 static void mc_bp_resume(void)
 {
 	int cpu = smp_processor_id();
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

 	if (uci->valid && uci->mc)
 		microcode_ops->apply_microcode(cpu);
 }

 static struct syscore_ops mc_syscore_ops = {
 	.resume			= mc_bp_resume,
 };

 static __cpuinit int
 mc_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
 	struct device *dev;

 	dev = get_cpu_device(cpu);
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
 		microcode_update_cpu(cpu);
 	case CPU_DOWN_FAILED:
 	case CPU_DOWN_FAILED_FROZEN:
 		pr_debug("CPU%d added\n", cpu);
 		if (sysfs_create_group(&dev->kobj, &mc_attr_group))
 			pr_err("Failed to create group for CPU%d\n", cpu);
 		break;
 	case CPU_DOWN_PREPARE:
 	case CPU_DOWN_PREPARE_FROZEN:
 		/* Suspend is in progress, only remove the interface */
 		sysfs_remove_group(&dev->kobj, &mc_attr_group);
 		pr_debug("CPU%d removed\n", cpu);
 		break;

 	/*
 	 * When a CPU goes offline, don't free up or invalidate the copy of
 	 * the microcode in kernel memory, so that we can reuse it when the
 	 * CPU comes back online without unnecessarily requesting the userspace
 	 * for it again.
 	 */
 	case CPU_UP_CANCELED_FROZEN:
 		/* The CPU refused to come up during a system resume */
 		microcode_fini_cpu(cpu);
 		break;
 	}
 	return NOTIFY_OK;
 }

 static struct notifier_block __refdata mc_cpu_notifier = {
 	.notifier_call	= mc_cpu_callback,
 };

 #ifdef MODULE
 /* Autoload on Intel and AMD systems */
 static const struct x86_cpu_id __initconst microcode_id[] = {
 #ifdef CONFIG_MICROCODE_INTEL
 	{ X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, },
 #endif
 #ifdef CONFIG_MICROCODE_AMD
 	{ X86_VENDOR_AMD, X86_FAMILY_ANY, X86_MODEL_ANY, },
 #endif
 	{}
 };
 MODULE_DEVICE_TABLE(x86cpu, microcode_id);
 #endif

 static struct attribute *cpu_root_microcode_attrs[] = {
 	&dev_attr_reload.attr,
 	NULL
 };

 static struct attribute_group cpu_root_microcode_group = {
 	.name  = "microcode",
 	.attrs = cpu_root_microcode_attrs,
 };

 static int __init microcode_init(void)
 {
 	struct cpuinfo_x86 *c = &cpu_data(0);
 	int error;

 	if (c->x86_vendor == X86_VENDOR_INTEL)
 		microcode_ops = init_intel_microcode();
 	else if (c->x86_vendor == X86_VENDOR_AMD)
 		microcode_ops = init_amd_microcode();
 	else
 		pr_err("no support for this CPU vendor\n");

 	if (!microcode_ops)
 		return -ENODEV;

 	microcode_pdev = platform_device_register_simple("microcode", -1,
 							 NULL, 0);
 	if (IS_ERR(microcode_pdev))
 		return PTR_ERR(microcode_pdev);

 	get_online_cpus();
 	mutex_lock(&microcode_mutex);

 	error = subsys_interface_register(&mc_cpu_interface);
 	if (!error)
 		perf_check_microcode();
 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();

 	if (error)
 		goto out_pdev;

 	error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
 				   &cpu_root_microcode_group);

 	if (error) {
 		pr_err("Error creating microcode group!\n");
 		goto out_driver;
 	}

 	error = microcode_dev_init();
 	if (error)
 		goto out_ucode_group;

 	register_syscore_ops(&mc_syscore_ops);
 	register_hotcpu_notifier(&mc_cpu_notifier);

 	pr_info("Microcode Update Driver: v" MICROCODE_VERSION
 		" <tigran@aivazian.fsnet.co.uk>, Peter Oruba\n");

 	return 0;

  out_ucode_group:
 	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
 			   &cpu_root_microcode_group);

  out_driver:
 	get_online_cpus();
 	mutex_lock(&microcode_mutex);

 	subsys_interface_unregister(&mc_cpu_interface);

 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();

  out_pdev:
 	platform_device_unregister(microcode_pdev);
 	return error;

 }
 module_init(microcode_init);

 static void __exit microcode_exit(void)
 {
 	struct cpuinfo_x86 *c = &cpu_data(0);

 	microcode_dev_exit();

 	unregister_hotcpu_notifier(&mc_cpu_notifier);
 	unregister_syscore_ops(&mc_syscore_ops);

 	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
 			   &cpu_root_microcode_group);

 	get_online_cpus();
 	mutex_lock(&microcode_mutex);

 	subsys_interface_unregister(&mc_cpu_interface);

 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();

 	platform_device_unregister(microcode_pdev);

 	microcode_ops = NULL;

 	if (c->x86_vendor == X86_VENDOR_AMD)
 		exit_amd_microcode();

 	pr_info("Microcode Update Driver: v" MICROCODE_VERSION " removed.\n");
 }
 module_exit(microcode_exit);
	/*
	* Intel CPU Microcode Update Driver for Linux
	*
	* Copyright (C) 2000-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
	* 2006 Shaohua Li <shaohua.li@intel.com>
	*
	* This driver allows to upgrade microcode on Intel processors
	* belonging to IA-32 family - PentiumPro, Pentium II,
	* Pentium III, Xeon, Pentium 4, etc.
	*
	* Reference: Section 8.11 of Volume 3a, IA-32 Intel? Architecture
	* Software Developer's Manual
	* Order Number 253668 or free download from:
	*
	* http://developer.intel.com/Assets/PDF/manual/253668.pdf
	*
	* For more information, go to http://www.urbanmyth.org/microcode
	*
	* 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; either version
	* 2 of the License, or (at your option) any later version.
	*
	* 1.0 16 Feb 2000, Tigran Aivazian <tigran@sco.com>
	* Initial release.
	* 1.01 18 Feb 2000, Tigran Aivazian <tigran@sco.com>
	* Added read() support + cleanups.
	* 1.02 21 Feb 2000, Tigran Aivazian <tigran@sco.com>
	* Added 'device trimming' support. open(O_WRONLY) zeroes
	* and frees the saved copy of applied microcode.
	* 1.03 29 Feb 2000, Tigran Aivazian <tigran@sco.com>
	* Made to use devfs (/dev/cpu/microcode) + cleanups.
	* 1.04 06 Jun 2000, Simon Trimmer <simon@veritas.com>
	* Added misc device support (now uses both devfs and misc).
	* Added MICROCODE_IOCFREE ioctl to clear memory.
	* 1.05 09 Jun 2000, Simon Trimmer <simon@veritas.com>
	* Messages for error cases (non Intel & no suitable microcode).
	* 1.06 03 Aug 2000, Tigran Aivazian <tigran@veritas.com>
	* Removed ->release(). Removed exclusive open and status bitmap.
	* Added microcode_rwsem to serialize read()/write()/ioctl().
	* Removed global kernel lock usage.
	* 1.07 07 Sep 2000, Tigran Aivazian <tigran@veritas.com>
	* Write 0 to 0x8B msr and then cpuid before reading revision,
	* so that it works even if there were no update done by the
	* BIOS. Otherwise, reading from 0x8B gives junk (which happened
	* to be 0 on my machine which is why it worked even when I
	* disabled update by the BIOS)
	* Thanks to Eric W. Biederman <ebiederman@lnxi.com> for the fix.
	* 1.08 11 Dec 2000, Richard Schaal <richard.schaal@intel.com> and
	* Tigran Aivazian <tigran@veritas.com>
	* Intel Pentium 4 processor support and bugfixes.
	* 1.09 30 Oct 2001, Tigran Aivazian <tigran@veritas.com>
	* Bugfix for HT (Hyper-Threading) enabled processors
	* whereby processor resources are shared by all logical processors
	* in a single CPU package.
	* 1.10 28 Feb 2002 Asit K Mallick <asit.k.mallick@intel.com> and
	* Tigran Aivazian <tigran@veritas.com>,
	* Serialize updates as required on HT processors due to
	* speculative nature of implementation.
	* 1.11 22 Mar 2002 Tigran Aivazian <tigran@veritas.com>
	* Fix the panic when writing zero-length microcode chunk.
	* 1.12 29 Sep 2003 Nitin Kamble <nitin.a.kamble@intel.com>,
	* Jun Nakajima <jun.nakajima@intel.com>
	* Support for the microcode updates in the new format.
	* 1.13 10 Oct 2003 Tigran Aivazian <tigran@veritas.com>
	* Removed ->read() method and obsoleted MICROCODE_IOCFREE ioctl
	* because we no longer hold a copy of applied microcode
	* in kernel memory.
	* 1.14 25 Jun 2004 Tigran Aivazian <tigran@veritas.com>
	* Fix sigmatch() macro to handle old CPUs with pf == 0.
	* Thanks to Stuart Swales for pointing out this bug.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/platform_device.h>
	#include <linux/miscdevice.h>
	#include <linux/capability.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/cpu.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/syscore_ops.h>

	#include <asm/microcode.h>
	#include <asm/processor.h>
	#include <asm/cpu_device_id.h>
	#include <asm/perf_event.h>

	MODULE_DESCRIPTION("Microcode Update Driver");
	MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");
	MODULE_LICENSE("GPL");

	#define MICROCODE_VERSION "2.00"

	static struct microcode_ops *microcode_ops;

	/*
	* Synchronization.
	*
	* All non cpu-hotplug-callback call sites use:
	*
	* - microcode_mutex to synchronize with each other;
	* - get/put_online_cpus() to synchronize with
	* the cpu-hotplug-callback call sites.
	*
	* We guarantee that only a single cpu is being
	* updated at any particular moment of time.
	*/
	static DEFINE_MUTEX(microcode_mutex);

	struct ucode_cpu_info ucode_cpu_info[NR_CPUS];
	EXPORT_SYMBOL_GPL(ucode_cpu_info);

	/*
	* Operations that are run on a target cpu:
	*/

	struct cpu_info_ctx {
	struct cpu_signature *cpu_sig;
	int err;
	};

	static void collect_cpu_info_local(void *arg)
	{
	struct cpu_info_ctx *ctx = arg;

	ctx->err = microcode_ops->collect_cpu_info(smp_processor_id(),
	ctx->cpu_sig);
	}

	static int collect_cpu_info_on_target(int cpu, struct cpu_signature *cpu_sig)
	{
	struct cpu_info_ctx ctx = { .cpu_sig = cpu_sig, .err = 0 };
	int ret;

	ret = smp_call_function_single(cpu, collect_cpu_info_local, &ctx, 1);
	if (!ret)
	ret = ctx.err;

	return ret;
	}

	static int collect_cpu_info(int cpu)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
	int ret;

	memset(uci, 0, sizeof(*uci));

	ret = collect_cpu_info_on_target(cpu, &uci->cpu_sig);
	if (!ret)
	uci->valid = 1;

	return ret;
	}

	struct apply_microcode_ctx {
	int err;
	};

	static void apply_microcode_local(void *arg)
	{
	struct apply_microcode_ctx *ctx = arg;

	ctx->err = microcode_ops->apply_microcode(smp_processor_id());
	}

	static int apply_microcode_on_target(int cpu)
	{
	struct apply_microcode_ctx ctx = { .err = 0 };
	int ret;

	ret = smp_call_function_single(cpu, apply_microcode_local, &ctx, 1);
	if (!ret)
	ret = ctx.err;

	return ret;
	}

	#ifdef CONFIG_MICROCODE_OLD_INTERFACE
	static int do_microcode_update(const void __user *buf, size_t size)
	{
	int error = 0;
	int cpu;

	for_each_online_cpu(cpu) {
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
	enum ucode_state ustate;

	if (!uci->valid)
	continue;

	ustate = microcode_ops->request_microcode_user(cpu, buf, size);
	if (ustate == UCODE_ERROR) {
	error = -1;
	break;
	} else if (ustate == UCODE_OK)
	apply_microcode_on_target(cpu);
	}

	return error;
	}

	static int microcode_open(struct inode inode, struct file file)
	{
	return capable(CAP_SYS_RAWIO) ? nonseekable_open(inode, file) : -EPERM;
	}

	static ssize_t microcode_write(struct file file, const char __user buf,
	size_t len, loff_t *ppos)
	{
	ssize_t ret = -EINVAL;

	if ((len >> PAGE_SHIFT) > totalram_pages) {
	pr_err("too much data (max %ld pages)\n", totalram_pages);
	return ret;
	}

	get_online_cpus();
	mutex_lock(&microcode_mutex);

	if (do_microcode_update(buf, len) == 0)
	ret = (ssize_t)len;

	if (ret > 0)
	perf_check_microcode();

	mutex_unlock(&microcode_mutex);
	put_online_cpus();

	return ret;
	}

	static const struct file_operations microcode_fops = {
	.owner = THIS_MODULE,
	.write = microcode_write,
	.open = microcode_open,
	.llseek = no_llseek,
	};

	static struct miscdevice microcode_dev = {
	.minor = MICROCODE_MINOR,
	.name = "microcode",
	.nodename = "cpu/microcode",
	.fops = &microcode_fops,
	};

	static int __init microcode_dev_init(void)
	{
	int error;

	error = misc_register(&microcode_dev);
	if (error) {
	pr_err("can't misc_register on minor=%d\n", MICROCODE_MINOR);
	return error;
	}

	return 0;
	}

	static void __exit microcode_dev_exit(void)
	{
	misc_deregister(&microcode_dev);
	}

	MODULE_ALIAS_MISCDEV(MICROCODE_MINOR);
	MODULE_ALIAS("devname:cpu/microcode");
	#else
	#define microcode_dev_init() 0
	#define microcode_dev_exit() do { } while (0)
	#endif

	/* fake device for request_firmware */
	static struct platform_device *microcode_pdev;

	static int reload_for_cpu(int cpu)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
	int err = 0;

	if (uci->valid) {
	enum ucode_state ustate;

	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev);
	if (ustate == UCODE_OK)
	apply_microcode_on_target(cpu);
	else
	if (ustate == UCODE_ERROR)
	err = -EINVAL;
	}

	return err;
	}

	static ssize_t reload_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t size)
	{
	unsigned long val;
	int cpu;
	ssize_t ret = 0, tmp_ret;

	ret = kstrtoul(buf, 0, &val);
	if (ret)
	return ret;

	if (val != 1)
	return size;

	get_online_cpus();
	mutex_lock(&microcode_mutex);
	for_each_online_cpu(cpu) {
	tmp_ret = reload_for_cpu(cpu);
	if (tmp_ret != 0)
	pr_warn("Error reloading microcode on CPU %d\n", cpu);

	/* save retval of the first encountered reload error */
	if (!ret)
	ret = tmp_ret;
	}
	if (!ret)
	perf_check_microcode();
	mutex_unlock(&microcode_mutex);
	put_online_cpus();

	if (!ret)
	ret = size;

	return ret;
	}

	static ssize_t version_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

	return sprintf(buf, "0x%x\n", uci->cpu_sig.rev);
	}

	static ssize_t pf_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

	return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
	}

	static DEVICE_ATTR(reload, 0200, NULL, reload_store);
	static DEVICE_ATTR(version, 0400, version_show, NULL);
	static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);

	static struct attribute *mc_default_attrs[] = {
	&dev_attr_version.attr,
	&dev_attr_processor_flags.attr,
	NULL
	};

	static struct attribute_group mc_attr_group = {
	.attrs = mc_default_attrs,
	.name = "microcode",
	};

	static void microcode_fini_cpu(int cpu)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

	microcode_ops->microcode_fini_cpu(cpu);
	uci->valid = 0;
	}

	static enum ucode_state microcode_resume_cpu(int cpu)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

	if (!uci->mc)
	return UCODE_NFOUND;

	pr_debug("CPU%d updated upon resume\n", cpu);
	apply_microcode_on_target(cpu);

	return UCODE_OK;
	}

	static enum ucode_state microcode_init_cpu(int cpu)
	{
	enum ucode_state ustate;

	if (collect_cpu_info(cpu))
	return UCODE_ERROR;

	/* --dimm. Trigger a delayed update? */
	if (system_state != SYSTEM_RUNNING)
	return UCODE_NFOUND;

	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev);

	if (ustate == UCODE_OK) {
	pr_debug("CPU%d updated upon init\n", cpu);
	apply_microcode_on_target(cpu);
	}

	return ustate;
	}

	static enum ucode_state microcode_update_cpu(int cpu)
	{
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
	enum ucode_state ustate;

	if (uci->valid)
	ustate = microcode_resume_cpu(cpu);
	else
	ustate = microcode_init_cpu(cpu);

	return ustate;
	}

	static int mc_device_add(struct device dev, struct subsys_interface sif)
	{
	int err, cpu = dev->id;

	if (!cpu_online(cpu))
	return 0;

	pr_debug("CPU%d added\n", cpu);

	err = sysfs_create_group(&dev->kobj, &mc_attr_group);
	if (err)
	return err;

	if (microcode_init_cpu(cpu) == UCODE_ERROR)
	return -EINVAL;

	return err;
	}

	static int mc_device_remove(struct device dev, struct subsys_interface sif)
	{
	int cpu = dev->id;

	if (!cpu_online(cpu))
	return 0;

	pr_debug("CPU%d removed\n", cpu);
	microcode_fini_cpu(cpu);
	sysfs_remove_group(&dev->kobj, &mc_attr_group);
	return 0;
	}

	static struct subsys_interface mc_cpu_interface = {
	.name = "microcode",
	.subsys = &cpu_subsys,
	.add_dev = mc_device_add,
	.remove_dev = mc_device_remove,
	};

	/**
	* mc_bp_resume - Update boot CPU microcode during resume.
	*/
	static void mc_bp_resume(void)
	{
	int cpu = smp_processor_id();
	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

	if (uci->valid && uci->mc)
	microcode_ops->apply_microcode(cpu);
	}

	static struct syscore_ops mc_syscore_ops = {
	.resume = mc_bp_resume,
	};

	static __cpuinit int
	mc_cpu_callback(struct notifier_block nb, unsigned long action, void hcpu)
	{
	unsigned int cpu = (unsigned long)hcpu;
	struct device *dev;

	dev = get_cpu_device(cpu);
	switch (action) {
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
	microcode_update_cpu(cpu);
	case CPU_DOWN_FAILED:
	case CPU_DOWN_FAILED_FROZEN:
	pr_debug("CPU%d added\n", cpu);
	if (sysfs_create_group(&dev->kobj, &mc_attr_group))
	pr_err("Failed to create group for CPU%d\n", cpu);
	break;
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
	/* Suspend is in progress, only remove the interface */
	sysfs_remove_group(&dev->kobj, &mc_attr_group);
	pr_debug("CPU%d removed\n", cpu);
	break;

	/*
	* When a CPU goes offline, don't free up or invalidate the copy of
	* the microcode in kernel memory, so that we can reuse it when the
	* CPU comes back online without unnecessarily requesting the userspace
	* for it again.
	*/
	case CPU_UP_CANCELED_FROZEN:
	/* The CPU refused to come up during a system resume */
	microcode_fini_cpu(cpu);
	break;
	}
	return NOTIFY_OK;
	}

	static struct notifier_block __refdata mc_cpu_notifier = {
	.notifier_call = mc_cpu_callback,
	};

	#ifdef MODULE
	/* Autoload on Intel and AMD systems */
	static const struct x86_cpu_id __initconst microcode_id[] = {
	#ifdef CONFIG_MICROCODE_INTEL
	{ X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, },
	#endif
	#ifdef CONFIG_MICROCODE_AMD
	{ X86_VENDOR_AMD, X86_FAMILY_ANY, X86_MODEL_ANY, },
	#endif
	{}
	};
	MODULE_DEVICE_TABLE(x86cpu, microcode_id);
	#endif

	static struct attribute *cpu_root_microcode_attrs[] = {
	&dev_attr_reload.attr,
	NULL
	};

	static struct attribute_group cpu_root_microcode_group = {
	.name = "microcode",
	.attrs = cpu_root_microcode_attrs,
	};

	static int __init microcode_init(void)
	{
	struct cpuinfo_x86 *c = &cpu_data(0);
	int error;

	if (c->x86_vendor == X86_VENDOR_INTEL)
	microcode_ops = init_intel_microcode();
	else if (c->x86_vendor == X86_VENDOR_AMD)
	microcode_ops = init_amd_microcode();
	else
	pr_err("no support for this CPU vendor\n");

	if (!microcode_ops)
	return -ENODEV;

	microcode_pdev = platform_device_register_simple("microcode", -1,
	NULL, 0);
	if (IS_ERR(microcode_pdev))
	return PTR_ERR(microcode_pdev);

	get_online_cpus();
	mutex_lock(&microcode_mutex);

	error = subsys_interface_register(&mc_cpu_interface);
	if (!error)
	perf_check_microcode();
	mutex_unlock(&microcode_mutex);
	put_online_cpus();

	if (error)
	goto out_pdev;

	error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
	&cpu_root_microcode_group);

	if (error) {
	pr_err("Error creating microcode group!\n");
	goto out_driver;
	}

	error = microcode_dev_init();
	if (error)
	goto out_ucode_group;

	register_syscore_ops(&mc_syscore_ops);
	register_hotcpu_notifier(&mc_cpu_notifier);

	pr_info("Microcode Update Driver: v" MICROCODE_VERSION
	" <tigran@aivazian.fsnet.co.uk>, Peter Oruba\n");

	return 0;

	out_ucode_group:
	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
	&cpu_root_microcode_group);

	out_driver:
	get_online_cpus();
	mutex_lock(&microcode_mutex);

	subsys_interface_unregister(&mc_cpu_interface);

	mutex_unlock(&microcode_mutex);
	put_online_cpus();

	out_pdev:
	platform_device_unregister(microcode_pdev);
	return error;

	}
	module_init(microcode_init);

	static void __exit microcode_exit(void)
	{
	struct cpuinfo_x86 *c = &cpu_data(0);

	microcode_dev_exit();

	unregister_hotcpu_notifier(&mc_cpu_notifier);
	unregister_syscore_ops(&mc_syscore_ops);

	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
	&cpu_root_microcode_group);

	get_online_cpus();
	mutex_lock(&microcode_mutex);

	subsys_interface_unregister(&mc_cpu_interface);

	mutex_unlock(&microcode_mutex);
	put_online_cpus();

	platform_device_unregister(microcode_pdev);

	microcode_ops = NULL;

	if (c->x86_vendor == X86_VENDOR_AMD)
	exit_amd_microcode();

	pr_info("Microcode Update Driver: v" MICROCODE_VERSION " removed.\n");
	}
	module_exit(microcode_exit);