[PATCH 1/1] UefiCpuPkg/MpInitLib: Reduce reset vector memory pressure

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

From: Tom Lendacky <thomas.lendacky@amd.com>

The AP reset vector stack allocation is only required if running as an
SEV-ES guest. Since the reset vector allocation is below 1MB in memory,
eliminate the requirement for bare-metal systems and non SEV-ES guests
to allocate the extra stack area, which can be large if the
PcdCpuMaxLogicalProcessorNumber value is large.

Cc: Garrett Kirkendall <garrett.kirkendall@amd.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 07426274f639..39af2f9fba7d 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1152,7 +1152,15 @@ GetApResetStackSize (
   VOID
   )
 {
-  return AP_RESET_STACK_SIZE * PcdGet32(PcdCpuMaxLogicalProcessorNumber);
+  //
+  // The AP reset stack is only used by SEV-ES guests. Don't add to the
+  // allocation if not necessary.
+  //
+  if (PcdGetBool (PcdSevEsIsEnabled) == TRUE) {
+    return AP_RESET_STACK_SIZE * PcdGet32(PcdCpuMaxLogicalProcessorNumber);
+  } else {
+    return 0;
+  }
 }
 
 /**
-- 
2.28.0