[PATCH resend 1/7] MdePkg: introduce MM communicate 2 protocol

["Ard Biesheuvel" <ard.biesheuvel@arm.com>]

Add the protocol definition of the MM communicate 2 protocol,
which has been introduced by version 1.7 errata A of the PI spec.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
---
 MdePkg/Include/Protocol/MmCommunication2.h | 69 ++++++++++++++++++++
 MdePkg/MdePkg.dec                          |  7 ++
 2 files changed, 76 insertions(+)

diff --git a/MdePkg/Include/Protocol/MmCommunication2.h b/MdePkg/Include/Protocol/MmCommunication2.h
new file mode 100644
index 000000000000..05f56dcae53e
--- /dev/null
+++ b/MdePkg/Include/Protocol/MmCommunication2.h
@@ -0,0 +1,69 @@
+/** @file
+  EFI MM Communication Protocol 2 as defined in the PI 1.7 errata A specification.
+
+  This protocol provides a means of communicating between drivers outside of MM and MMI
+  handlers inside of MM.
+
+  Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2020, Arm Limited. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _MM_COMMUNICATION2_H_
+#define _MM_COMMUNICATION2_H_
+
+#include <Protocol/MmCommunication.h>
+
+#define EFI_MM_COMMUNICATION2_PROTOCOL_GUID \
+  { \
+    0x378daedc, 0xf06b, 0x4446, { 0x83, 0x14, 0x40, 0xab, 0x93, 0x3c, 0x87, 0xa3 } \
+  }
+
+typedef struct _EFI_MM_COMMUNICATION2_PROTOCOL  EFI_MM_COMMUNICATION2_PROTOCOL;
+
+/**
+  Communicates with a registered handler.
+
+  This function provides a service to send and receive messages from a registered UEFI service.
+
+  @param[in] This                The EFI_MM_COMMUNICATION_PROTOCOL instance.
+  @param[in] CommBufferPhysical  Physical address of the MM communication buffer
+  @param[in] CommBufferVirtual   Virtual address of the MM communication buffer
+  @param[in] CommSize            The size of the data buffer being passed in. On exit, the size of data
+                                 being returned. Zero if the handler does not wish to reply with any data.
+                                 This parameter is optional and may be NULL.
+
+  @retval EFI_SUCCESS            The message was successfully posted.
+  @retval EFI_INVALID_PARAMETER  CommBufferPhysical was NULL or CommBufferVirtual was NULL.
+  @retval EFI_BAD_BUFFER_SIZE    The buffer is too large for the MM implementation.
+                                 If this error is returned, the MessageLength field
+                                 in the CommBuffer header or the integer pointed by
+                                 CommSize, are updated to reflect the maximum payload
+                                 size the implementation can accommodate.
+  @retval EFI_ACCESS_DENIED      The CommunicateBuffer parameter or CommSize parameter,
+                                 if not omitted, are in address range that cannot be
+                                 accessed by the MM environment.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EFI_MM_COMMUNICATE2)(
+  IN CONST EFI_MM_COMMUNICATION2_PROTOCOL   *This,
+  IN OUT VOID                               *CommBufferPhysical,
+  IN OUT VOID                               *CommBufferVirtual,
+  IN OUT UINTN                              *CommSize OPTIONAL
+  );
+
+///
+/// EFI MM Communication Protocol provides runtime services for communicating
+/// between DXE drivers and a registered MMI handler.
+///
+struct _EFI_MM_COMMUNICATION2_PROTOCOL {
+  EFI_MM_COMMUNICATE2  Communicate;
+};
+
+extern EFI_GUID gEfiMmCommunication2ProtocolGuid;
+
+#endif
+
diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec
index 6c37c2181c62..e2a79dd85db6 100644
--- a/MdePkg/MdePkg.dec
+++ b/MdePkg/MdePkg.dec
@@ -1277,6 +1277,13 @@ [Protocols]
   ## Include/Protocol/SpiSmmNorFlash.h
   gEfiSpiSmmNorFlashProtocolGuid         = { 0xaab18f19, 0xfe14, 0x4666, { 0x86, 0x04, 0x87, 0xff, 0x6d, 0x66, 0x2c, 0x9a }}
 
+  #
+  # Protocols defined in PI 1.7.
+  #
+
+  ## Include/Protocol/MmCommunication2.h
+  gEfiMmCommunication2ProtocolGuid  = { 0x378daedc, 0xf06b, 0x4446, { 0x83, 0x14, 0x40, 0xab, 0x93, 0x3c, 0x87, 0xa3 }}
+
   #
   # Protocols defined in UEFI2.1/UEFI2.0/EFI1.1
   #
-- 
2.17.1