UefiCpuPkg: Add SmmCpuPlatformHookBeforeMmiHandler

This patch is to add SmmCpuPlatformHookBeforeMmiHandler interface
in SmmCpuPlatformHookLib.

The new API can be used to perform the platform specific items
before executing MMI Handler. For example, Intel can leverage
this API to clear the pending SMI bit after all CPUs finish the
sync and before the MMI handlers. If so, the the redundant
SMI can be avoided after CPU exit from current SMI.

Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>

Author: Jiaxin Wu

UefiCpuPkg/Include/Library/SmmCpuPlatformHookLib.h

@@ -1,7 +1,7 @@
 /** @file
   Public include file for the SMM CPU Platform Hook Library.
 
-  Copyright (c) 2010 - 2015, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2010 - 2024, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -100,4 +100,19 @@ GetPlatformPageTableAttribute (
   OUT UINTN               *PageAttribute
   );
 
+/**
+  SMM CPU Platform Hook before executing MMI Handler.
+
+  This function can be used to perform the platform specific items before executing MMI Handler.
+
+  @retval EFI_SUCCESS      The smm cpu platform hook before executing MMI Handler is executed successfully.
+  @retval EFI_UNSUPPORTED  The smm cpu platform hook before executing MMI Handler is unsupported.
+
+**/
+EFI_STATUS
+EFIAPI
+SmmCpuPlatformHookBeforeMmiHandler (
+  VOID
+  );
+
 #endif

UefiCpuPkg/Library/SmmCpuPlatformHookLibNull/SmmCpuPlatformHookLibNull.c

@@ -1,7 +1,7 @@
 /** @file
 SMM CPU Platform Hook NULL library instance.
 
-Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2024, Intel Corporation. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -100,3 +100,21 @@ GetPlatformPageTableAttribute (
 {
   return EFI_UNSUPPORTED;
 }
+
+/**
+  SMM CPU Platform Hook before executing MMI Handler.
+
+  This function can be used to perform the platform specific items before executing MMI Handler.
+
+  @retval EFI_SUCCESS      The smm cpu platform hook before executing MMI Handler is executed successfully.
+  @retval EFI_UNSUPPORTED  The smm cpu platform hook before executing MMI Handler is unsupported.
+
+**/
+EFI_STATUS
+EFIAPI
+SmmCpuPlatformHookBeforeMmiHandler (
+  VOID
+  )
+{
+  return EFI_UNSUPPORTED;
+}