[Patch v3 3/3] UefiCpuPkg/MpInitLib: Load uCode once for each core.

[Eric Dong <eric.dong@intel.com>]

The SDM requires only one thread per core to load the
microcode.

This change enables this solution.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Eric Dong <eric.dong@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/Microcode.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c b/UefiCpuPkg/Library/MpInitLib/Microcode.c
index 351975e2a2..122c23469d 100644
--- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
+++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
@@ -61,6 +61,7 @@ MicrocodeDetect (
   VOID                                    *MicrocodeData;
   MSR_IA32_PLATFORM_ID_REGISTER           PlatformIdMsr;
   UINT32                                  ProcessorFlags;
+  UINT32                                  ThreadId;
 
   if (CpuMpData->MicrocodePatchRegionSize == 0) {
     //
@@ -77,6 +78,14 @@ MicrocodeDetect (
     return;
   }
 
+  GetProcessorLocationByApicId (GetInitialApicId (), NULL, NULL, &ThreadId);
+  if (ThreadId != 0) {
+    //
+    // Skip loading microcode if it is not the first thread in one core.
+    //
+    return;
+  }
+
   ExtendedTableLength = 0;
   //
   // Here data of CPUID leafs have not been collected into context buffer, so
-- 
2.15.0.windows.1