[PATCH v2 1/7] MdeModulePkg: Define memory attribute PPI

["Ard Biesheuvel" <ardb@kernel.org>]

Define a PPI interface that may be used by the PEI core or other PEIMs
to manage permissions on memory ranges. This is primarily intended for
restricting permissions to what is actually needed for correct execution
by the code in question, and for limiting the use of memory mappings
that are both writable and executable at the same time.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 MdeModulePkg/Include/Ppi/MemoryAttribute.h | 83 ++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec              |  3 +
 2 files changed, 86 insertions(+)

diff --git a/MdeModulePkg/Include/Ppi/MemoryAttribute.h b/MdeModulePkg/Include/Ppi/MemoryAttribute.h
new file mode 100644
index 0000000000000000..83bcc33a76719712
--- /dev/null
+++ b/MdeModulePkg/Include/Ppi/MemoryAttribute.h
@@ -0,0 +1,83 @@
+/** @file
+
+Copyright (c) 2023, Google LLC. All rights reserved.<BR>
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef EDKII_MEMORY_ATTRIBUTE_PPI_H_
+#define EDKII_MEMORY_ATTRIBUTE_PPI_H_
+
+#include <Uefi/UefiSpec.h>
+
+///
+/// Global ID for the EDKII_MEMORY_ATTRIBUTE_PPI.
+///
+#define EDKII_MEMORY_ATTRIBUTE_PPI_GUID \
+  { \
+    0x1be840de, 0x2d92, 0x41ec, { 0xb6, 0xd3, 0x19, 0x64, 0x13, 0x50, 0x51, 0xfb } \
+  }
+
+///
+/// Forward declaration for the EDKII_MEMORY_ATTRIBUTE_PPI.
+///
+typedef struct _EDKII_MEMORY_ATTRIBUTE_PPI EDKII_MEMORY_ATTRIBUTE_PPI;
+
+/**
+  Set the requested memory permission attributes on a region of memory.
+
+  BaseAddress and Length must be aligned to EFI_PAGE_SIZE.
+
+  Attributes must contain a combination of EFI_MEMORY_RP, EFI_MEMORY_RO and
+  EFI_MEMORY_XP, and specifies the attributes that must be set for the
+  region in question. Attributes that are omitted will be cleared from the
+  region only if they are set in AttributeMask.
+
+  AttributeMask must contain a combination of EFI_MEMORY_RP, EFI_MEMORY_RO and
+  EFI_MEMORY_XP, and specifies the attributes that the call will operate on.
+  AttributeMask must not be 0x0, and must contain at least the bits set in
+  Attributes.
+
+  @param[in]  This              The protocol instance pointer.
+  @param[in]  BaseAddress       The physical address that is the start address
+                                of a memory region.
+  @param[in]  Length            The size in bytes of the memory region.
+  @param[in]  Attributes        Memory attributes to set or clear.
+  @param[in]  AttributeMask     Mask of memory attributes to operate on.
+
+  @retval EFI_SUCCESS           The attributes were set for the memory region.
+  @retval EFI_INVALID_PARAMETER Length is zero.
+                                AttributeMask is zero.
+                                AttributeMask lacks bits set in Attributes.
+                                BaseAddress or Length is not suitably aligned.
+  @retval EFI_UNSUPPORTED       The processor does not support one or more
+                                bytes of the memory resource range specified
+                                by BaseAddress and Length.
+                                The bit mask of attributes is not supported for
+                                the memory resource range specified by
+                                BaseAddress and Length.
+  @retval EFI_OUT_OF_RESOURCES  Requested attributes cannot be applied due to
+                                lack of system resources.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *EDKII_MEMORY_ATTRIBUTE_SET_PERMISSIONS)(
+  IN  EDKII_MEMORY_ATTRIBUTE_PPI  *This,
+  IN  EFI_PHYSICAL_ADDRESS        BaseAddress,
+  IN  UINT64                      Length,
+  IN  UINT64                      Attributes,
+  IN  UINT64                      AttributeMask
+  );
+
+///
+/// This PPI contains a set of services to manage memory permission attributes.
+///
+struct _EDKII_MEMORY_ATTRIBUTE_PPI {
+  EDKII_MEMORY_ATTRIBUTE_SET_PERMISSIONS    SetPermissions;
+};
+
+extern EFI_GUID  gEdkiiMemoryAttributePpiGuid;
+
+#endif
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 95dd077e19b3a901..d65dae18aa81e569 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -528,6 +528,9 @@ [Ppis]
   gEdkiiPeiCapsuleOnDiskPpiGuid             = { 0x71a9ea61, 0x5a35, 0x4a5d, { 0xac, 0xef, 0x9c, 0xf8, 0x6d, 0x6d, 0x67, 0xe0 } }
   gEdkiiPeiBootInCapsuleOnDiskModePpiGuid   = { 0xb08a11e4, 0xe2b7, 0x4b75, { 0xb5, 0x15, 0xaf, 0x61, 0x6, 0x68, 0xbf, 0xd1  } }
 
+  ## Include/Ppi/MemoryAttribute.h
+  gEdkiiMemoryAttributePpiGuid              = { 0x1be840de, 0x2d92, 0x41ec, { 0xb6, 0xd3, 0x19, 0x64, 0x13, 0x50, 0x51, 0xfb } }
+
 [Protocols]
   ## Load File protocol provides capability to load and unload EFI image into memory and execute it.
   #  Include/Protocol/LoadPe32Image.h
-- 
2.39.2