MdeModulePkg/VarCheckPolicyLib: implement standalone MM version

This commit adds the VarCheckPolicyLib that will be able to
execute in the context of standalone MM.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Co-authored-by: Kun Qin <kun.q@outlook.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdeModulePkg/Library/VarCheckPolicyLib/VarCheckPolicyLib.h

@@ -0,0 +1,42 @@
+/** @file -- VarCheckPolicyLib.h
+This internal header file defines the common interface of constructor for
+VarCheckPolicyLib.
+
+Copyright (c) Microsoft Corporation. All rights reserved.
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _VAR_CHECK_POLICY_LIB_H_
+#define _VAR_CHECK_POLICY_LIB_H_
+
+/**
+  Common constructor function of VarCheckPolicyLib to register VarCheck handler
+  and SW MMI handlers.
+
+  @retval EFI_SUCCESS       The constructor executed correctly.
+
+**/
+EFI_STATUS
+EFIAPI
+VarCheckPolicyLibCommonConstructor (
+  VOID
+  );
+
+/**
+  This function is wrapper function to validate the buffer.
+
+  @param Buffer  The buffer start address to be checked.
+  @param Length  The buffer length to be checked.
+
+  @retval TRUE  This buffer is valid per processor architecture and not overlap with SMRAM/MMRAM.
+  @retval FALSE This buffer is not valid per processor architecture or overlap with SMRAM/MMRAM.
+**/
+BOOLEAN
+EFIAPI
+VarCheckPolicyIsBufferOutsideValid (
+  IN EFI_PHYSICAL_ADDRESS  Buffer,
+  IN UINT64                Length
+  );
+
+#endif // _VAR_CHECK_POLICY_LIB_H_