From fb46e9f7bd639b60cbb26e1efbd4d19e65115c0b Mon Sep 17 00:00:00 2001
From: sanglipeng <sanglipeng1@jd.com>
Date: Wed, 22 Nov 2023 18:41:41 +0800
Subject: [PATCH] Revert "x86/microcode: Rip out the OLD_INTERFACE"

stable inclusion
from stable-v5.10.173
commit 9e56938f207241512aab787b17c88c96dc150b90
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8IOCW
CVE: NA

Reference: https://github.com/torvalds/linux/commit/9e56938f207241512aab787b17c88c96dc150b90

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

This reverts commit ab873cbbab393da2ee7aa047cb8d5401cffc5a94.

Signed-off-by: sanglipeng <sanglipeng1@jd.com>

Conflicts:
	arch/x86/Kconfig
---
 arch/x86/Kconfig                     |  12 ++++
 arch/x86/kernel/cpu/microcode/core.c | 100 +++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f8e6060eaeb7..64567773fc55 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1347,6 +1347,18 @@ config MICROCODE_LATE_LOADING
 	  not guarantee that cores might not softlock after the loading. Therefore,
 	  use this at your own risk. Late loading taints the kernel too.
 
+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
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 707a385943b4..ef814e28f7ae 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -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;
+	}
+
+	cpus_read_lock();
+	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);
+	cpus_read_unlock();
+
+	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;
 
@@ -787,6 +879,10 @@ 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);
@@ -797,6 +893,10 @@ int __init microcode_init(void)
 
 	return 0;
 
+ out_ucode_group:
+	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
+			   &cpu_root_microcode_group);
+
  out_driver:
 	cpus_read_lock();
 	mutex_lock(&microcode_mutex);
-- 
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