linux-kernel - [PATCH] x86/microcode: Print previous version of microcode after reload

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Message-Id: <20220829181030.722891-1-ashok.raj@intel.com>
Date:   Mon, 29 Aug 2022 18:10:30 +0000
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     "LKML Mailing List" <linux-kernel@...r.kernel.org>,
        X86-kernel <x86@...nel.org>, Dave Hansen <dave.hansen@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        Ingo Molnar <mingo@...nel.org>,
        "Ashok Raj" <ashok.raj@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH] x86/microcode: Print previous version of microcode after reload

It will be useful to print both old and new versions of microcode after a
reload is complete.

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
---
 arch/x86/kernel/cpu/microcode/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index ad57e0e4d674..6a41cee242f6 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -491,7 +491,7 @@ static int __reload_late(void *info)
  */
 static int microcode_reload_late(void)
 {
-	int ret;
+	int old = boot_cpu_data.microcode, ret;
 
 	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");
@@ -503,7 +503,8 @@ static int microcode_reload_late(void)
 	if (ret == 0)
 		microcode_check();
 
-	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;
 }
-- 
2.32.0