From: Ashok Raj <ashok.raj@intel.com>
Date: Mon, 9 Jan 2023 07:35:50 -0800
Subject: x86/microcode: Add a parameter to microcode_check() to store CPU
 capabilities
Git-commit: ab31c74455c64e69342ddab21fd9426fcbfefde7
Patch-mainline: v6.3-rc1
References: git-fixes

Add a parameter to store CPU capabilities before performing a microcode
update so that CPU capabilities can be compared before and after update.

  [ bp: Massage. ]

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230109153555.4986-2-ashok.raj@intel.com

Acked-by: Nikolay Borisov <nik.borisov@suse.com>
---
 arch/x86/include/asm/processor.h     |    2 +-
 arch/x86/kernel/cpu/common.c         |   19 +++++++++++--------
 arch/x86/kernel/cpu/microcode/core.c |    7 ++++---
 3 files changed, 16 insertions(+), 12 deletions(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -830,7 +830,7 @@ bool xen_set_default_idle(void);
 #endif
 
 void stop_this_cpu(void *dummy);
-void microcode_check(void);
+void microcode_check(struct cpuinfo_x86 *prev_info);
 
 enum l1tf_mitigations {
 	L1TF_MITIGATION_OFF,
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2139,30 +2139,33 @@ void cpu_init_secondary(void)
 }
 #endif
 
-/*
+/**
+ * microcode_check() - Check if any CPU capabilities changed after an update.
+ * @prev_info:	CPU capabilities stored before an update.
+ *
  * The microcode loader calls this upon late microcode load to recheck features,
  * only when microcode has been updated. Caller holds microcode_mutex and CPU
  * hotplug lock.
  */
-void microcode_check(void)
+void microcode_check(struct cpuinfo_x86 *prev_info)
 {
-	struct cpuinfo_x86 info;
-
 	perf_check_microcode();
 
 	/* Reload CPUID max function as it might've changed. */
-	info.cpuid_level = cpuid_eax(0);
+	prev_info->cpuid_level = cpuid_eax(0);
 
 	/*
 	 * Copy all capability leafs to pick up the synthetic ones so that
 	 * memcmp() below doesn't fail on that. The ones coming from CPUID will
 	 * get overwritten in get_cpu_cap().
 	 */
-	memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+	memcpy(&prev_info->x86_capability, &boot_cpu_data.x86_capability,
+	       sizeof(prev_info->x86_capability));
 
-	get_cpu_cap(&info);
+	get_cpu_cap(prev_info);
 
-	if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
+	if (!memcmp(&prev_info->x86_capability, &boot_cpu_data.x86_capability,
+		    sizeof(prev_info->x86_capability)))
 		return;
 
 	pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -599,16 +599,17 @@ wait_for_siblings:
  */
 static int microcode_reload_late(void)
 {
-	int ret;
+	int old = boot_cpu_data.microcode, ret;
+	struct cpuinfo_x86 prev_info;
 
 	atomic_set(&late_cpus_in,  0);
 	atomic_set(&late_cpus_out, 0);
 
 	ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
 	if (ret == 0)
-		microcode_check();
+		microcode_check(&prev_info);
 
-	pr_info("Reload completed, microcode revision: 0x%x\n", boot_cpu_data.microcode);
+	pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n", old, boot_cpu_data.microcode);
 
 	return ret;
 }