StandaloneMmPkg: Produce StandaloneMM Entry/Exit Notify Protocol.

Produce StandaloneMM Entry/Exit Notify Protocol for PlatformHook.
This replaces the SMM core platform hook implementation in the
traditional SMM (Edk2\MdeModulePkg\Include\Library\SmmCorePlatformHookLib.h).
Unlike traditional SMM, Standalone MM prefers a more generic method to
perform platform-specific tasks before and after the SMI handler. Therefore,
it introduces the gMmEntryNotifyProtocolGuid and gMmExitNotifyProtocolGuid
protocols to notify the SMM entry and exit. This approach is more flexible
for the platform, eliminating the need to place all tasks in
PlatformHookBeforeSmmDispatch() and PlatformHookAfterSmmDispatch(), thus
platform code can depend on the protocol notification to perform
platform-specific tasks.

Signed-off-by: Diat Siah Yap <diat.siah.yap@intel.com>

StandaloneMmPkg/Core/StandaloneMmCore.c

@@ -505,6 +505,7 @@ MmEntryPoint (
   EFI_MM_COMMUNICATE_HEADER  *CommunicateHeader;
   MM_COMM_BUFFER_STATUS      *CommunicationStatus;
   UINTN                      BufferSize;
+  EFI_HANDLE                 MmHandle;
 
   DEBUG ((DEBUG_INFO, "MmEntryPoint ...\n"));
 
@@ -514,9 +515,22 @@ MmEntryPoint (
   CopyMem (&gMmCoreMmst.MmStartupThisAp, MmEntryContext, sizeof (EFI_MM_ENTRY_CONTEXT));
 
   //
-  // Call platform hook before Mm Dispatch
+  // Install a protocol to notify BeforeMmDispatch.
   //
-  // PlatformHookBeforeMmDispatch ();
+  MmHandle = NULL;
+  Status   = MmInstallProtocolInterface (
+               &MmHandle,
+               &gEfiMmEntryNotifyProtocolGuid,
+               EFI_NATIVE_INTERFACE,
+               NULL
+               );
+  if (!EFI_ERROR (Status)) {
+    MmUninstallProtocolInterface (
+      MmHandle,
+      &gEfiMmEntryNotifyProtocolGuid,
+      NULL
+      );
+  }
 
   //
   // Check to see if this is a Synchronous MMI sent through the MM Communication
@@ -589,6 +603,24 @@ MmEntryPoint (
   //
   MmiManage (NULL, NULL, NULL, NULL);
 
+  //
+  // Install a protocol to notify AfterMmDispatch.
+  //
+  MmHandle = NULL;
+  Status   = MmInstallProtocolInterface (
+               &MmHandle,
+               &gEfiMmExitNotifyProtocolGuid,
+               EFI_NATIVE_INTERFACE,
+               NULL
+               );
+  if (!EFI_ERROR (Status)) {
+    MmUninstallProtocolInterface (
+      MmHandle,
+      &gEfiMmExitNotifyProtocolGuid,
+      NULL
+      );
+  }
+
   //
   // TBD: Do not use private data structure ?
   //

StandaloneMmPkg/Core/StandaloneMmCore.inf

@@ -63,6 +63,8 @@
   gEfiLoadedImageProtocolGuid                   ## PRODUCES
   gEfiMmConfigurationProtocolGuid               ## CONSUMES
   gEfiMmEndOfPeiProtocol                        ## PRODUCES
+  gEfiMmEntryNotifyProtocolGuid                 ## PRODUCES
+  gEfiMmExitNotifyProtocolGuid                  ## PRODUCES
 
 [Guids]
   gAprioriGuid                                  ## SOMETIMES_CONSUMES   ## File

StandaloneMmPkg/StandaloneMmPkg.dec

@@ -43,6 +43,10 @@
 
   gEventMmDispatchGuid                     = { 0x7e6efffa, 0x69b4, 0x4c1b, { 0xa4, 0xc7, 0xaf, 0xf9, 0xc9, 0x24, 0x4f, 0xee }}
 
+[Protocols]
+  gEfiMmEntryNotifyProtocolGuid            = { 0x9bfbcc5f, 0x6435, 0x46d3, { 0xb9, 0xa5, 0x70, 0xfb, 0xa4, 0x71, 0xe1, 0x26 }}
+  gEfiMmExitNotifyProtocolGuid             = { 0x0e265f48, 0x47c0, 0x471f, { 0x9c, 0x83, 0xc6, 0xd6, 0x57, 0x64, 0x21, 0xa4 }}
+
 [Ppis]
   gMmCoreFvLocationPpiGuid                 = { 0x47a00618, 0x237a, 0x4386, { 0x8f, 0xc5, 0x2a, 0x86, 0xd8, 0xac, 0x41, 0x05 }}