[PATCH v4 2/7] MdePkg: MmCommunication: Introduce EFI_MM_COMMUNICATE_HEADER_V3 to MdePkg

["Kun Qin" <kuqin12@gmail.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3398
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3430

This change introduces a new definition for MM communicate header
structure, intending to provide better portability between different
architectures (IA32 & X64) and adapt to flexible array supported by
modern compilers.

The original MessageLength field of EFI_MM_COMMUNICATE_HEADER, as a
generic definition, was used for both PEI and DXE MM communication. On a
system that supports PEI MM launch, but operates PEI in 32bit mode and MM
foundation in 64bit, the current EFI_MM_COMMUNICATE_HEADER definition
will cause structure parse error due to UINTN used. This introduction
removes the architecture dependent field by defining this field as
UINT64.

The new signature could help identifying whether the data received is
compiliant with this new data structure, which will help for binary
release modules to identify usage of legacy data structure.

Version field is also added to indicate the current version of header in
case there is need for minor modification in the future.

The data field of MM communicate message is replaced with flexible array
to allow users not having to consume extra data during communicate and
author code more intrinsically.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Marvin Häuser <mhaeuser@posteo.de>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>

Signed-off-by: Kun Qin <kuqin12@gmail.com>
---

Notes:
    v3:
    - Newly introduced communicate v3
    - Used flexible arrays [Marvin]
    - Added static assert [Michael]
    
    v4:
    - Rebased with uncrusitify changes.

 MdePkg/Include/Pi/PiMultiPhase.h | 57 ++++++++++++++++++++
 MdePkg/MdePkg.dec                |  5 ++
 2 files changed, 62 insertions(+)

diff --git a/MdePkg/Include/Pi/PiMultiPhase.h b/MdePkg/Include/Pi/PiMultiPhase.h
index a7e95820ef65..178606eacfb0 100644
--- a/MdePkg/Include/Pi/PiMultiPhase.h
+++ b/MdePkg/Include/Pi/PiMultiPhase.h
@@ -103,6 +103,17 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #define EFI_SMRAM_CLOSED  EFI_MMRAM_CLOSED
 #define EFI_SMRAM_LOCKED  EFI_MMRAM_LOCKED
 
+///
+/// MM Communicate header constants
+///
+#define COMMUNICATE_HEADER_V3_GUID \
+  { \
+    0x68e8c853, 0x2ba9, 0x4dd7, { 0x9a, 0xc0, 0x91, 0xe1, 0x61, 0x55, 0xc9, 0x35 } \
+  }
+
+#define EFI_MM_COMMUNICATE_HEADER_V3_SIGNATURE  0x4D434833 // "MCH3"
+#define EFI_MM_COMMUNICATE_HEADER_V3_VERSION    3
+
 ///
 /// Structure describing a MMRAM region and its accessibility attributes.
 ///
@@ -149,6 +160,50 @@ typedef struct _EFI_MM_RESERVED_MMRAM_REGION {
   UINT64                  MmramReservedSize;
 } EFI_MM_RESERVED_MMRAM_REGION;
 
+#pragma pack(1)
+
+///
+/// To avoid confusion in interpreting frames, the buffer communicating to MM core through
+/// EFI_MM_COMMUNICATE3 or later should always start with EFI_MM_COMMUNICATE_HEADER_V3.
+///
+typedef struct {
+  ///
+  /// Indicator GUID for MM core that the communication buffer is compliant with this v3 header.
+  /// Must be gCommunicateHeaderV3Guid.
+  ///
+  EFI_GUID    HeaderGuid;
+  ///
+  /// Signature to indicate data is compliant with new MM communicate header structure.
+  /// Must be "MCH3".
+  ///
+  UINT32      Signature;
+  ///
+  /// MM communicate data format version, MM foundation entry point should check if incoming
+  /// data is a supported format before proceeding.
+  /// Must be 3.
+  ///
+  UINT32      Version;
+  ///
+  /// Allows for disambiguation of the message format.
+  ///
+  EFI_GUID    MessageGuid;
+  ///
+  /// Describes the size of MessageData (in bytes) and does not include the size of the header.
+  ///
+  UINT64      MessageSize;
+  ///
+  /// Designates an array of bytes that is MessageSize in size.
+  ///
+  UINT8       MessageData[];
+} EFI_MM_COMMUNICATE_HEADER_V3;
+
+#pragma pack()
+
+STATIC_ASSERT (
+  (sizeof (EFI_MM_COMMUNICATE_HEADER_V3) == OFFSET_OF (EFI_MM_COMMUNICATE_HEADER_V3, MessageData)), \
+  "sizeof (EFI_MM_COMMUNICATE_HEADER_V3) does not align with the beginning of flexible array MessageData"
+  );
+
 typedef enum {
   EFI_PCD_TYPE_8,
   EFI_PCD_TYPE_16,
@@ -208,4 +263,6 @@ EFI_STATUS
   IN VOID  *ProcedureArgument
   );
 
+extern EFI_GUID  gCommunicateHeaderV3Guid;
+
 #endif
diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec
index 59b405928bf8..11c08e617511 100644
--- a/MdePkg/MdePkg.dec
+++ b/MdePkg/MdePkg.dec
@@ -826,6 +826,11 @@ [Guids]
   ## Include/Protocol/CcMeasurement.h
   gEfiCcFinalEventsTableGuid     = { 0xdd4a4648, 0x2de7, 0x4665, { 0x96, 0x4d, 0x21, 0xd9, 0xef, 0x5f, 0xb4, 0x46 }}
 
+  #
+  # GUID indicates the MM communication data is compliant with v3 communication header.
+  #
+  gCommunicateHeaderV3Guid       = { 0x68e8c853, 0x2ba9, 0x4dd7, { 0x9a, 0xc0, 0x91, 0xe1, 0x61, 0x55, 0xc9, 0x35 } }
+
 [Guids.IA32, Guids.X64]
   ## Include/Guid/Cper.h
   gEfiIa32X64ErrorTypeCacheCheckGuid = { 0xA55701F5, 0xE3EF, 0x43de, { 0xAC, 0x72, 0x24, 0x9B, 0x57, 0x3F, 0xAD, 0x2C }}
-- 
2.34.1.windows.1