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@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20220829181030.722891-1-ashok.raj@intel.com

Author: Ashok Raj

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;
 }