[PATCH 2/2] UefiCpuPkg: MpInitLib: Exclude code no pertinent to AMD processors.

[Leo Duran <leo.duran@amd.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2556

This patch uses the newly exported StandardSignatureIsAuthenticAMD function
from LocalApicLib, to divert code paths not pertinent to AMD processors.
Specifically, the PlatformId MSR and embedded Microcode patches are not
relevant on AMD-based platforms.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Leo Duran <leo.duran@amd.com>
---
 UefiCpuPkg/Library/MpInitLib/Microcode.c | 17 +++++++++++++++--
 UefiCpuPkg/Library/MpInitLib/MpLib.c     | 11 +++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c b/UefiCpuPkg/Library/MpInitLib/Microcode.c
index 1562959..750681d 100644
--- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
+++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
@@ -2,6 +2,8 @@
   Implementation of loading microcode on processors.
 
   Copyright (c) 2015 - 2020, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2020, AMD Inc. All rights reserved.<BR>
+
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -97,9 +99,13 @@ MicrocodeDetect (
   UINT32                                  ThreadId;
   BOOLEAN                                 IsBspCallIn;
 
-  if (CpuMpData->MicrocodePatchRegionSize == 0) {
+  //
+  // NOTE: Embedded Microcode patches are not relevant on AMD platforms.
+  //
+  if (CpuMpData->MicrocodePatchRegionSize == 0 ||
+      StandardSignatureIsAuthenticAMD ()) {
     //
-    // There is no microcode patches
+    // There are no microcode patches
     //
     return;
   }
@@ -350,6 +356,13 @@ IsProcessorMatchedMicrocodePatch (
   UINTN          Index;
   CPU_AP_DATA    *CpuData;
 
+  //
+  // NOTE: PlatformId or embedded Microcode patches are not relevant on AMD platforms.
+  //
+  if (StandardSignatureIsAuthenticAMD ()) {
+    return FALSE;
+  }
+
   for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
     CpuData = &CpuMpData->CpuData[Index];
     if ((ProcessorSignature == CpuData->ProcessorSignature) &&
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index d0fbc17..290e7bf 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -2,6 +2,8 @@
   CPU MP Initialize Library common functions.
 
   Copyright (c) 2016 - 2020, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2020, AMD Inc. All rights reserved.<BR>
+
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -564,8 +566,13 @@ InitializeApData (
   CpuMpData->CpuData[ProcessorNumber].Waiting    = FALSE;
   CpuMpData->CpuData[ProcessorNumber].CpuHealthy = (BistData == 0) ? TRUE : FALSE;
 
-  PlatformIdMsr.Uint64 = AsmReadMsr64 (MSR_IA32_PLATFORM_ID);
-  CpuMpData->CpuData[ProcessorNumber].PlatformId = (UINT8) PlatformIdMsr.Bits.PlatformId;
+  //
+  // NOTE: PlatformId is not relevant on AMD platforms.
+  //
+  if (!StandardSignatureIsAuthenticAMD ()) {
+    PlatformIdMsr.Uint64 = AsmReadMsr64 (MSR_IA32_PLATFORM_ID);
+    CpuMpData->CpuData[ProcessorNumber].PlatformId = (UINT8)PlatformIdMsr.Bits.PlatformId;
+  }
 
   AsmCpuid (
     CPUID_VERSION_INFO,
-- 
2.7.4