1 files changed, 18 insertions, 1 deletions
diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 7839c24976..93fc63bf93 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -29,6 +29,11 @@ VOID             *mReservedApLoopFunc = NULL;
 UINTN            mReservedTopOfApStack;
 volatile UINT32  mNumberToFinish = 0;
 
+//
+// Begin wakeup buffer allocation below 0x88000
+//
+STATIC EFI_PHYSICAL_ADDRESS mSevEsDxeWakeupBuffer = 0x88000;
+
 /**
   Enable Debug Agent to support source debugging on AP function.
 
@@ -102,7 +107,14 @@ GetWakeupBuffer (
   // LagacyBios driver depends on CPU Arch protocol which guarantees below
   // allocation runs earlier than LegacyBios driver.
   //
-  StartAddress = 0x88000;
+  if (PcdGetBool (PcdSevEsIsEnabled)) {
+    //
+    // SEV-ES Wakeup buffer should be under 0x88000 and under any previous one
+    //
+    StartAddress = mSevEsDxeWakeupBuffer;
+  } else {
+    StartAddress = 0x88000;
+  }
   Status = gBS->AllocatePages (
                   AllocateMaxAddress,
                   MemoryType,
@@ -112,6 +124,11 @@ GetWakeupBuffer (
   ASSERT_EFI_ERROR (Status);
   if (EFI_ERROR (Status)) {
     StartAddress = (EFI_PHYSICAL_ADDRESS) -1;
+  } else if (PcdGetBool (PcdSevEsIsEnabled)) {
+    //
+    // Next SEV-ES wakeup buffer allocation must be below this allocation
+    //
+    mSevEsDxeWakeupBuffer = StartAddress;
   }
 
   DEBUG ((DEBUG_INFO, "WakeupBufferStart = %x, WakeupBufferSize = %x\n",