[edk2-platforms: PATCH] MinPlatformPkg/SaveMemoryConfig: Variable may not be locked.

["Chiu, Chasel" <chasel.chiu@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3829

Fixed the bug that existing variable will not be locked when it is
identical with hob data, also switch to VariablePolicyProtocol for
locking variables.

This patch also updated SaveMemoryConfig driver to be unloaded after
execution because it does not produce any service protocol. To achieve
this goal the DxeRuntimeVariableWriteLib should close registered
ExitBootService events in its DESTRUCTOR.

Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Eric Dong <eric.dong@intel.com>
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
---
 Platform/Intel/MinPlatformPkg/FspWrapper/SaveMemoryConfig/SaveMemoryConfig.c                    | 12 +++++++++---
 Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.c   | 62 ++++++++++++++++++++++++++++++++++++++++++++++----------------
 Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.inf |  8 +++++---
 3 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/Platform/Intel/MinPlatformPkg/FspWrapper/SaveMemoryConfig/SaveMemoryConfig.c b/Platform/Intel/MinPlatformPkg/FspWrapper/SaveMemoryConfig/SaveMemoryConfig.c
index 820585f676..0ae5511fed 100644
--- a/Platform/Intel/MinPlatformPkg/FspWrapper/SaveMemoryConfig/SaveMemoryConfig.c
+++ b/Platform/Intel/MinPlatformPkg/FspWrapper/SaveMemoryConfig/SaveMemoryConfig.c
@@ -2,7 +2,7 @@
   This is the driver that locates the MemoryConfigurationData HOB, if it
   exists, and saves the data to nvRAM.
 
-Copyright (c) 2017 - 2021, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2017 - 2022, Intel Corporation. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -18,6 +18,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #include <Library/BaseMemoryLib.h>
 #include <Library/LargeVariableReadLib.h>
 #include <Library/LargeVariableWriteLib.h>
+#include <Library/VariableWriteLib.h>
 #include <Guid/FspNonVolatileStorageHob2.h>
 
 /**
@@ -86,6 +87,11 @@ SaveMemoryConfigEntryPoint (
             Status = GetLargeVariable (L"FspNvsBuffer", &gFspNvsBufferVariableGuid, &BufferSize, VariableData);
             if (!EFI_ERROR (Status) && (BufferSize == DataSize) && (0 == CompareMem (HobData, VariableData, DataSize))) {
               DataIsIdentical = TRUE;
+              //
+              // No need to update Variable, only lock it.
+              //
+              Status = VarLibVariableRequestToLock (L"FspNvsBuffer",  &gFspNvsBufferVariableGuid);
+              ASSERT_EFI_ERROR (Status);
             }
             FreePool (VariableData);
           }
@@ -106,7 +112,7 @@ SaveMemoryConfigEntryPoint (
   }
 
   //
-  // This driver cannot be unloaded because DxeRuntimeVariableWriteLib constructor will register ExitBootServices callback.
+  // This driver does not produce any protocol services, so always unload it.
   //
-  return EFI_SUCCESS;
+  return EFI_REQUEST_UNLOAD_IMAGE;
 }
diff --git a/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.c b/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.c
index 9ed59f8827..e7d0c5ec34 100644
--- a/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.c
+++ b/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.c
@@ -10,7 +10,7 @@
   Using this library allows code to be written in a generic manner that can be
   used in DXE or SMM without modification.
 
-  Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2021 - 2022, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -18,14 +18,16 @@
 #include <Uefi.h>
 
 #include <Guid/EventGroup.h>
-#include <Protocol/VariableLock.h>
+#include <Library/VariablePolicyHelperLib.h>
 
 #include <Library/UefiLib.h>
 #include <Library/DebugLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiRuntimeServicesTableLib.h>
 
-STATIC EDKII_VARIABLE_LOCK_PROTOCOL  *mVariableWriteLibVariableLock = NULL;
+STATIC EDKII_VARIABLE_POLICY_PROTOCOL  *mVariableWriteLibVariablePolicy = NULL;
+EFI_EVENT                              mExitBootServiceEvent;
+EFI_EVENT                              mLegacyBootEvent;
 
 /**
   Sets the value of a variable.
@@ -144,7 +146,7 @@ VarLibIsVariableRequestToLockSupported (
   VOID
   )
 {
-  if (mVariableWriteLibVariableLock != NULL) {
+  if (mVariableWriteLibVariablePolicy != NULL) {
     return TRUE;
   } else {
     return FALSE;
@@ -178,16 +180,46 @@ VarLibVariableRequestToLock (
 {
   EFI_STATUS    Status = EFI_UNSUPPORTED;
 
-  if (mVariableWriteLibVariableLock != NULL) {
-    Status = mVariableWriteLibVariableLock->RequestToLock (
-                                              mVariableWriteLibVariableLock,
-                                              VariableName,
-                                              VendorGuid
-                                              );
+  if (mVariableWriteLibVariablePolicy != NULL) {
+    Status = RegisterBasicVariablePolicy (
+               mVariableWriteLibVariablePolicy,
+               (CONST EFI_GUID*) VendorGuid,
+               (CONST CHAR16 *) VariableName,
+               VARIABLE_POLICY_NO_MIN_SIZE,
+               VARIABLE_POLICY_NO_MAX_SIZE,
+               VARIABLE_POLICY_NO_MUST_ATTR,
+               VARIABLE_POLICY_NO_CANT_ATTR,
+               VARIABLE_POLICY_TYPE_LOCK_NOW
+               );
+    ASSERT_EFI_ERROR (Status);
   }
   return Status;
 }
 
+/**
+  Close events when driver unloaded.
+
+  @param[in] ImageHandle  A handle for the image that is initializing this driver
+  @param[in] SystemTable  A pointer to the EFI system table
+
+  @retval    EFI_SUCCESS  The initialization finished successfully.
+**/
+EFI_STATUS
+EFIAPI
+DxeRuntimeVariableWriteLibDestructor (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  if (mExitBootServiceEvent != 0) {
+    gBS->CloseEvent (mExitBootServiceEvent);
+  }
+  if (mLegacyBootEvent != 0) {
+    gBS->CloseEvent (mLegacyBootEvent);
+  }
+  return EFI_SUCCESS;
+}
+
 /**
   Exit Boot Services Event notification handler.
 
@@ -202,7 +234,7 @@ DxeRuntimeVariableWriteLibOnExitBootServices (
   IN  VOID                         *Context
   )
 {
-  mVariableWriteLibVariableLock = NULL;
+  mVariableWriteLibVariablePolicy = NULL;
 }
 
 /**
@@ -227,13 +259,11 @@ DxeRuntimeVariableWriteLibConstructor (
   )
 {
   EFI_STATUS    Status;
-  EFI_EVENT     ExitBootServiceEvent;
-  EFI_EVENT     LegacyBootEvent;
 
   //
   // Locate VariableLockProtocol.
   //
-  Status = gBS->LocateProtocol (&gEdkiiVariableLockProtocolGuid, NULL, (VOID **)&mVariableWriteLibVariableLock);
+  Status = gBS->LocateProtocol (&gEdkiiVariablePolicyProtocolGuid, NULL, (VOID **)&mVariableWriteLibVariablePolicy);
   ASSERT_EFI_ERROR (Status);
 
   //
@@ -245,7 +275,7 @@ DxeRuntimeVariableWriteLibConstructor (
              DxeRuntimeVariableWriteLibOnExitBootServices,
              NULL,
              &gEfiEventExitBootServicesGuid,
-             &ExitBootServiceEvent
+             &mExitBootServiceEvent
              );
   ASSERT_EFI_ERROR (Status);
 
@@ -257,7 +287,7 @@ DxeRuntimeVariableWriteLibConstructor (
              TPL_NOTIFY,
              DxeRuntimeVariableWriteLibOnExitBootServices,
              NULL,
-             &LegacyBootEvent
+             &mLegacyBootEvent
              );
   ASSERT_EFI_ERROR (Status);
 
diff --git a/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.inf b/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.inf
index 704a8ac7cc..f83090c847 100644
--- a/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.inf
+++ b/Platform/Intel/MinPlatformPkg/Library/DxeRuntimeVariableWriteLib/DxeRuntimeVariableWriteLib.inf
@@ -10,7 +10,7 @@
 # Using this library allows code to be written in a generic manner that can be
 # used in DXE or SMM without modification.
 #
-# Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2021 - 2022, Intel Corporation. All rights reserved.<BR>
 #
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -24,6 +24,7 @@
   MODULE_TYPE                    = DXE_RUNTIME_DRIVER
   LIBRARY_CLASS                  = VariableWriteLib|DXE_CORE DXE_DRIVER DXE_RUNTIME_DRIVER UEFI_APPLICATION UEFI_DRIVER
   CONSTRUCTOR                    = DxeRuntimeVariableWriteLibConstructor
+  DESTRUCTOR                     = DxeRuntimeVariableWriteLibDestructor
 
 [Packages]
   MdePkg/MdePkg.dec
@@ -37,13 +38,14 @@
   UefiLib
   UefiBootServicesTableLib
   UefiRuntimeServicesTableLib
+  VariablePolicyHelperLib
 
 [Guids]
   gEfiEventExitBootServicesGuid       ## CONSUMES ## Event
 
 [Protocols]
   gEfiVariableWriteArchProtocolGuid   ## CONSUMES
-  gEdkiiVariableLockProtocolGuid      ## CONSUMES
+  gEdkiiVariablePolicyProtocolGuid      ## CONSUMES
 
 [Depex]
-  gEfiVariableWriteArchProtocolGuid AND gEdkiiVariableLockProtocolGuid
+  gEfiVariableWriteArchProtocolGuid AND gEdkiiVariablePolicyProtocolGuid
-- 
2.28.0.windows.1