[tip: x86/microcode] x86/microcode: Print previous version of microcode after reload

[tip-bot2 for Ashok Raj]

The following commit has been merged into the x86/microcode branch of tip:

Commit-ID:     7fce8d6eccbc31a561d07c79f359ad09f0424347
Gitweb:        https://git.kernel.org/tip/7fce8d6eccbc31a561d07c79f359ad09f0424347
Author:        Ashok Raj <ashok.raj@xxxxxxxxx>
AuthorDate:    Mon, 29 Aug 2022 18:10:30 
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Fri, 02 Sep 2022 08:01:58 +02:00

x86/microcode: Print previous version of microcode after reload

Print both old and new versions of microcode after a reload is complete
because knowing the previous microcode version is sometimes important
from a debugging perspective.

  [ bp: Massage commit message. ]

Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Tony Luck <tony.luck@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220829181030.722891-1-ashok.raj@xxxxxxxxx
---
 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 ad57e0e..6a41cee 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -491,7 +491,7 @@ wait_for_siblings:
  */
 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;
 }