UefiCpuPkg: Always load microcode patch on AP processor.

This patch updates the microcode loader to always perform a microcode
detect and load on both BSP and AP processor. This is to fix a potential
microcode revision mismatch issue in below situation:
1. Assume there are two microcode co-exists in flash: one production
   version and one debug version microcode.
2. FIT loads production microcode to BSP and all AP.
3. UefiCpuPkg loader loads debug microcode to BSP, and skip the loading
   on AP.
As a result, different microcode patches are loaded to BSP and AP, and
trigger microcode mismatch error during OS boot.

BZ link: https://bugzilla.tianocore.org/show_bug.cgi?id=2431

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Siyuan Fu <siyuan.fu@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>

1 files changed, 0 insertions, 6 deletions

diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c b/UefiCpuPkg/Library/MpInitLib/Microcode.c
index a9d06dd409..8f4d4da40c 100644
--- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
+++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
@@ -105,12 +105,6 @@ MicrocodeDetect (
 

   CurrentRevision = GetCurrentMicrocodeSignature ();

   IsBspCallIn     = (ProcessorNumber == (UINTN)CpuMpData->BspNumber) ? TRUE : FALSE;

-  if (CurrentRevision != 0 && !IsBspCallIn) {

-    //

-    // Skip loading microcode if it has been loaded successfully

-    //

-    return;

-  }

 

   GetProcessorLocationByApicId (GetInitialApicId (), NULL, NULL, &ThreadId);

   if (ThreadId != 0) {