From ff04469d33512d29a5b1afa9c99ec3a152795360 Mon Sep 17 00:00:00 2001
From: Hongbin1 Zhang <hongbin1.zhang@intel.com>
Date: Fri, 31 May 2024 15:26:10 +0800
Subject: [PATCH] MdeModulePkg: Add MM Communication Buffer definition

The MM communicate buffer facilitates data sharing between non-MM
and MM code.
The MM IPL code allocates a "fixed" runtime type memory as the MM
communication buffer, and communicates its address and size to MM
Core via MmCommBuffer GUIDed HOB.
Here, "fixed" implies that the buffer's location remains constant
throughout the boot process.
Data is exchanged between the MM Communication PPI/Protocol and a
software MMI handler using this fixed MM communication buffer.

Signed-off-by: Hongbin1 Zhang <hongbin1.zhang@intel.com>
Co-authored-by: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Co-authored-by: Ray Ni <ray.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Wei6 Xu <wei6.xu@intel.com>
Cc: Dun Tan <dun.tan@intel.com>
Cc: Yuanhao Xie <yuanhao.xie@intel.com>
---
 MdeModulePkg/Include/Guid/MmCommBuffer.h | 63 ++++++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec            |  3 ++
 2 files changed, 66 insertions(+)
 create mode 100644 MdeModulePkg/Include/Guid/MmCommBuffer.h

diff --git a/MdeModulePkg/Include/Guid/MmCommBuffer.h b/MdeModulePkg/Include/Guid/MmCommBuffer.h
new file mode 100644
index 0000000000..df4ea317eb
--- /dev/null
+++ b/MdeModulePkg/Include/Guid/MmCommBuffer.h
@@ -0,0 +1,63 @@
+/** @file
+  MM Communication buffer data.
+
+Copyright (c) 2024, Intel Corporation. All rights reserved.<BR>
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef MM_COMM_BUFFER_H_
+#define MM_COMM_BUFFER_H_
+
+///
+/// The GUID of the MM Communication buffer HOB.
+///
+#define MM_COMM_BUFFER_HOB_GUID \
+  { 0x6c2a2520, 0x0131, 0x4aee, { 0xa7, 0x50, 0xcc, 0x38, 0x4a, 0xac, 0xe8, 0xc6 }}
+
+///
+/// The MM communicate buffer facilitates data sharing between non-MM and MM code.
+/// The MM IPL code allocates a "fixed" runtime type memory as the MM communication buffer,
+/// and communicates its address and size to MM Core via MmCommBuffer GUIDed HOB.
+/// Here, "fixed" implies that the buffer's location remains constant throughout the boot process.
+/// Data is exchanged between the MM Communication PPI/Protocol and a software MMI handler
+/// using this fixed MM communication buffer.
+///
+typedef struct {
+  ///
+  /// The address of the 4-KiB aligned fixed MM communication buffer.
+  ///
+  EFI_PHYSICAL_ADDRESS    PhysicalStart;
+
+  ///
+  /// Size of the fixed MM communication buffer, in 4KiB pages.
+  ///
+  UINT64                  NumberOfPages;
+
+  ///
+  /// Point to MM_COMM_BUFFER_STATUS structure.
+  ///
+  EFI_PHYSICAL_ADDRESS    Status;
+} MM_COMM_BUFFER;
+
+typedef struct {
+  ///
+  /// Whether the data in the fixed MM communication buffer is valid when entering from non-MM to MM.
+  ///
+  BOOLEAN    IsCommBufferValid;
+
+  ///
+  /// The return status when returning from MM to non-MM.
+  ///
+  UINT64     ReturnStatus;
+
+  ///
+  /// The size in bytes of the output buffer when returning from MM to non-MM.
+  ///
+  UINT64     ReturnBufferSize;
+} MM_COMM_BUFFER_STATUS;
+
+extern EFI_GUID  gMmCommBufferHobGuid;
+
+#endif
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 693e45911b..e71a4dd5e3 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -485,6 +485,9 @@
   ## HOB GUID to get ACPI table after FSP is done. The ACPI table that related SOC will be pass by this HOB.
   gAcpiTableHobGuid = { 0xf9886b57, 0x8a35, 0x455e, { 0xbb, 0xb1, 0x14, 0x65, 0x5e, 0x7b, 0xe7, 0xec }}
 
+  ## Include/Guid/MmCommBuffer.h
+  gMmCommBufferHobGuid  = { 0x6c2a2520, 0x0131, 0x4aee, { 0xa7, 0x50, 0xcc, 0x38, 0x4a, 0xac, 0xe8, 0xc6 }}
+
 [Ppis]
   ## Include/Ppi/FirmwareVolumeShadowPpi.h
   gEdkiiPeiFirmwareVolumeShadowPpiGuid = { 0x7dfe756c, 0xed8d, 0x4d77, {0x9e, 0xc4, 0x39, 0x9a, 0x8a, 0x81, 0x51, 0x16 } }