Commit 0bb88756 authored by Aichun Shi's avatar Aichun Shi
Browse files

Revert "x86/microcode: Rip out the OLD_INTERFACE" 

Intel inclusion
category: feature
feature: Backport Intel In Field Scan(IFS) multi-blob images support
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I6L337


CVE: N/A
Reference: N/A

Intel-SIG: Revert commit 05a2ea3f ("x86/microcode: Rip out the
OLD_INTERFACE")

-------------------------------------

This reverts commit 05a2ea3f.

This revert is to recover old microcode interface /dev/cpu/microcode.

Signed-off-by: default avatarAichun Shi <aichun.shi@intel.com>
parent 0ccb8568

arch/x86/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -1336,6 +1336,18 @@ config MICROCODE_AMD 
	  If you select this option, microcode patch loading support for AMD

	  processors will be enabled.



config MICROCODE_OLD_INTERFACE

	bool "Ancient loading interface (DEPRECATED)"

	default n

	depends on MICROCODE

	help

	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface

	  which was used by userspace tools like iucode_tool and microcode.ctl.

	  It is inadequate because it runs too late to be able to properly

	  load microcode on a machine and it needs special tools. Instead, you

	  should've switched to the early loading method with the initrd or

	  builtin microcode by now: Documentation/x86/microcode.rst



config X86_MSR

	tristate "/dev/cpu/*/msr - Model-specific register support"

	help

arch/x86/kernel/cpu/microcode/core.c

+100 −0
Original line number Diff line number Diff line
@@ -390,6 +390,98 @@ static int apply_microcode_on_target(int cpu) 
	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_NEW) {

			apply_microcode_on_target(cpu);

		}

	}



	return error;

}



static int microcode_open(struct inode *inode, struct file *file)

{

	return capable(CAP_SYS_RAWIO) ? stream_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;

	unsigned long nr_pages = totalram_pages();



	if ((len >> PAGE_SHIFT) > nr_pages) {

		pr_err("too much data (max %ld pages)\n", nr_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);

}

#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;
@@ -781,6 +873,10 @@ int __init microcode_init(void) 
		goto out_driver;

	}



	error = microcode_dev_init();

	if (error)

		goto out_ucode_group;



	register_syscore_ops(&mc_syscore_ops);

	cpuhp_setup_state_nocalls(CPUHP_AP_MICROCODE_LOADER, "x86/microcode:starting",

				  mc_cpu_starting, NULL);
@@ -791,6 +887,10 @@ int __init microcode_init(void) 


	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);