linux-kernel - [PATCH v3 1/2] x86/microcode: Add a parameter to microcode

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Date:   Tue, 27 Dec 2022 13:01:43 -0800
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     X86-kernel <x86@...nel.org>,
        LKML Mailing List <linux-kernel@...r.kernel.org>,
        Ashok Raj <ashok.raj@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH v3 1/2] x86/microcode: Add a parameter to microcode_check() to store CPU capabilities

This is a preparation before the next patch uses this to compare CPU
capabilities after performing an update.

Add a parameter to store CPU capabilities before performing a microcode
update.

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Cc: x86 <x86@...nel.org>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Alison Schofield <alison.schofield@...el.com>
Cc: Reinette Chatre <reinette.chatre@...el.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/include/asm/processor.h     |  2 +-
 arch/x86/kernel/cpu/common.c         | 12 +++++-------
 arch/x86/kernel/cpu/microcode/core.c |  3 ++-
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4e35c66edeb7..387578049de0 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -697,7 +697,7 @@ bool xen_set_default_idle(void);
 #endif
 
 void __noreturn stop_this_cpu(void *dummy);
-void microcode_check(void);
+void microcode_check(struct cpuinfo_x86 *info);
 
 enum l1tf_mitigations {
 	L1TF_MITIGATION_OFF,
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9cfca3d7d0e2..b9c7529c920e 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2302,25 +2302,23 @@ void cpu_init_secondary(void)
  * only when microcode has been updated. Caller holds microcode_mutex and CPU
  * hotplug lock.
  */
-void microcode_check(void)
+void microcode_check(struct cpuinfo_x86 *info)
 {
-	struct cpuinfo_x86 info;
-
 	perf_check_microcode();
 
 	/* Reload CPUID max function as it might've changed. */
-	info.cpuid_level = cpuid_eax(0);
+	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(&info->x86_capability, &boot_cpu_data.x86_capability, sizeof(info->x86_capability));
 
-	get_cpu_cap(&info);
+	get_cpu_cap(info);
 
-	if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
+	if (!memcmp(&info->x86_capability, &boot_cpu_data.x86_capability, sizeof(info->x86_capability)))
 		return;
 
 	pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4cd7328177b..d86a4f910a6b 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -439,6 +439,7 @@ static int __reload_late(void *info)
 static int microcode_reload_late(void)
 {
 	int old = boot_cpu_data.microcode, ret;
+	struct cpuinfo_x86 info;
 
 	pr_err("Attempting late microcode loading - it is dangerous and taints the kernel.\n");
 	pr_err("You should switch to early loading, if possible.\n");
@@ -448,7 +449,7 @@ static int microcode_reload_late(void)
 
 	ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
 	if (ret == 0)
-		microcode_check();
+		microcode_check(&info);
 
 	pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n",
 		old, boot_cpu_data.microcode);
-- 
2.34.1