2 files changed, 7 insertions, 4 deletions
diff --git a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
index cd10b63c95..67e08a9e7e 100644
--- a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
+++ b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2014 - 2019, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2014 - 2022, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -38,7 +38,8 @@ typedef struct {
 } CONTEXT_STACK;
 
 //
-//   API return address           +0xB0
+//   API return address           +0xB8
+//   Reserved                     +0xB0
 //   push    API Parameter2       +0xA8
 //   push    API Parameter1       +0xA0
 //   push    FspInfoHeader        +0x98
@@ -54,6 +55,7 @@ typedef struct {
   UINT32    Flags[2];
   UINT64    FspInfoHeader;
   UINT64    ApiParam[2];
+  UINT64    Reserved;       // The reserved QWORD is needed for stack alignment in X64.
   UINT64    ApiRet;         // 64bit stack format is different from the 32bit one due to x64 calling convention
 } CONTEXT_STACK_64;
 
diff --git a/IntelFsp2Pkg/Library/BaseFspSwitchStackLib/X64/Stack.nasm b/IntelFsp2Pkg/Library/BaseFspSwitchStackLib/X64/Stack.nasm
index bd36fe4b8b..1ea1220608 100644
--- a/IntelFsp2Pkg/Library/BaseFspSwitchStackLib/X64/Stack.nasm
+++ b/IntelFsp2Pkg/Library/BaseFspSwitchStackLib/X64/Stack.nasm
@@ -47,7 +47,8 @@ ASM_PFX(Loader2PeiSwitchStack):
 ;------------------------------------------------------------------------------
 global ASM_PFX(FspSwitchStack)
 ASM_PFX(FspSwitchStack):
-    ; Save current contexts
+    ; Save current contexts. The format must align with CONTEXT_STACK_64.
+    push    rdx     ; Reserved QWORD for stack alignment
     push    rdx     ; ApiParam2
     push    rcx     ; ApiParam1
     push    rax     ; FspInfoHeader
@@ -67,6 +68,6 @@ ASM_PFX(FspSwitchStack):
     add     rsp, 16
     POPA_64
     popfq
-    add     rsp, 24 ; FspInfoHeader + ApiParam[2]
+    add     rsp, 32 ; FspInfoHeader + ApiParam[2] + Reserved QWORD
     ret