[PATCH] UefiCpuPkg/LocalApicLib: Exclude second SendIpi sequence on AMD processors.

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

On AMD processors the second SendIpi in the SendInitSipiSipi and
SendInitSipiSipiAllExcludingSelf routines is not required, and may cause
undesired side-effects during MP initialization.

This patch leverages the StandardSignatureIsAuthenticAMD check to exclude
the second SendIpi and its associated MicroSecondDelay (200).

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Leo Duran <leo.duran@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
---
 UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c             | 12 ++++++++----
 UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c | 12 ++++++++----
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c b/UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c
index b0b7e32..6e80536 100644
--- a/UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c
+++ b/UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c
@@ -554,8 +554,10 @@ SendInitSipiSipi (
   IcrLow.Bits.DeliveryMode = LOCAL_APIC_DELIVERY_MODE_STARTUP;
   IcrLow.Bits.Level = 1;
   SendIpi (IcrLow.Uint32, ApicId);
-  MicroSecondDelay (200);
-  SendIpi (IcrLow.Uint32, ApicId);
+  if (!StandardSignatureIsAuthenticAMD()) {
+    MicroSecondDelay (200);
+    SendIpi (IcrLow.Uint32, ApicId);
+  }
 }
 
 /**
@@ -588,8 +590,10 @@ SendInitSipiSipiAllExcludingSelf (
   IcrLow.Bits.Level = 1;
   IcrLow.Bits.DestinationShorthand = LOCAL_APIC_DESTINATION_SHORTHAND_ALL_EXCLUDING_SELF;
   SendIpi (IcrLow.Uint32, 0);
-  MicroSecondDelay (200);
-  SendIpi (IcrLow.Uint32, 0);
+  if (!StandardSignatureIsAuthenticAMD()) {
+    MicroSecondDelay (200);
+    SendIpi (IcrLow.Uint32, 0);
+  }
 }
 
 /**
diff --git a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
index 1f4dcf7..5d82836 100644
--- a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
+++ b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
@@ -649,8 +649,10 @@ SendInitSipiSipi (
   IcrLow.Bits.DeliveryMode = LOCAL_APIC_DELIVERY_MODE_STARTUP;
   IcrLow.Bits.Level = 1;
   SendIpi (IcrLow.Uint32, ApicId);
-  MicroSecondDelay (200);
-  SendIpi (IcrLow.Uint32, ApicId);
+  if (!StandardSignatureIsAuthenticAMD()) {
+    MicroSecondDelay (200);
+    SendIpi (IcrLow.Uint32, ApicId);
+  }
 }
 
 /**
@@ -683,8 +685,10 @@ SendInitSipiSipiAllExcludingSelf (
   IcrLow.Bits.Level = 1;
   IcrLow.Bits.DestinationShorthand = LOCAL_APIC_DESTINATION_SHORTHAND_ALL_EXCLUDING_SELF;
   SendIpi (IcrLow.Uint32, 0);
-  MicroSecondDelay (200);
-  SendIpi (IcrLow.Uint32, 0);
+  if (!StandardSignatureIsAuthenticAMD()) {
+    MicroSecondDelay (200);
+    SendIpi (IcrLow.Uint32, 0);
+  }
 }
 
 /**
-- 
2.7.4