[PATCH v2 01/12] MdeModulePkg: Define the VariablePolicy protocol interface

["Michael Kubacki" <michael.kubacki@outlook.com>]

From: Bret Barkelew <brbarkel@microsoft.com>

https://bugzilla.tianocore.org/show_bug.cgi?id=2522

VariablePolicy is an updated interface to
replace VarLock and VarCheckProtocol.

Add the VariablePolicy protocol interface
header and add to the MdeModulePkg.dec file.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
---
 MdeModulePkg/Include/Protocol/VariablePolicy.h | 157 ++++++++++++++++++++
 MdeModulePkg/MdeModulePkg.dec                  |  14 +-
 2 files changed, 170 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Include/Protocol/VariablePolicy.h b/MdeModulePkg/Include/Protocol/VariablePolicy.h
new file mode 100644
index 000000000000..2cd025860554
--- /dev/null
+++ b/MdeModulePkg/Include/Protocol/VariablePolicy.h
@@ -0,0 +1,157 @@
+/** @file -- VariablePolicy.h
+
+This protocol allows communication with Variable Policy Engine.
+
+Copyright (c) Microsoft Corporation.
+SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef __VARIABLE_POLICY_PROTOCOL__
+#define __VARIABLE_POLICY_PROTOCOL__
+
+#define VARIABLE_POLICY_PROTOCOL_REVISION   0x0000000000010000
+
+#define VARIABLE_POLICY_PROTOCOL_GUID \
+  { \
+    0x81D1675C, 0x86F6, 0x48DF, { 0xBD, 0x95, 0x9A, 0x6E, 0x4F, 0x09, 0x25, 0xC3 } \
+  }
+
+#define VARIABLE_POLICY_ENTRY_REVISION      0x00010000
+
+#pragma pack(push, 1)
+typedef struct {
+  UINT32   Version;
+  UINT16   Size;
+  UINT16   OffsetToName;
+  EFI_GUID Namespace;
+  UINT32   MinSize;
+  UINT32   MaxSize;
+  UINT32   AttributesMustHave;
+  UINT32   AttributesCantHave;
+  UINT8    LockPolicyType;
+  UINT8    Padding[3];
+  // UINT8    LockPolicy[];     // Variable Length Field
+  // CHAR16   Name[]            // Variable Length Field
+} VARIABLE_POLICY_ENTRY;
+
+#define     VARIABLE_POLICY_NO_MIN_SIZE             0
+#define     VARIABLE_POLICY_NO_MAX_SIZE             MAX_UINT32
+#define     VARIABLE_POLICY_NO_MUST_ATTR            0
+#define     VARIABLE_POLICY_NO_CANT_ATTR            0
+
+#define     VARIABLE_POLICY_TYPE_NO_LOCK            0
+#define     VARIABLE_POLICY_TYPE_LOCK_NOW           1
+#define     VARIABLE_POLICY_TYPE_LOCK_ON_CREATE     2
+#define     VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE  3
+
+typedef struct {
+  EFI_GUID Namespace;
+  UINT8    Value;
+  UINT8    Padding;
+  // CHAR16   Name[];           // Variable Length Field
+} VARIABLE_LOCK_ON_VAR_STATE_POLICY;
+#pragma pack(pop)
+
+/**
+  This API function disables the variable policy enforcement. If it's
+  already been called once, will return EFI_ALREADY_STARTED.
+
+  @retval     EFI_SUCCESS
+  @retval     EFI_ALREADY_STARTED   Has already been called once this boot.
+  @retval     EFI_WRITE_PROTECTED   Interface has been locked until reboot.
+  @retval     EFI_WRITE_PROTECTED   Interface option is disabled by platform PCD.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *DISABLE_VARIABLE_POLICY)(
+  VOID
+  );
+
+/**
+  This API function returns whether or not the policy engine is
+  currently being enforced.
+
+  @param[out]   State       Pointer to a return value for whether the policy enforcement
+                            is currently enabled.
+
+  @retval     EFI_SUCCESS
+  @retval     Others        An error has prevented this command from completing.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *IS_VARIABLE_POLICY_ENABLED)(
+  OUT BOOLEAN *State
+  );
+
+/**
+  This API function validates and registers a new policy with
+  the policy enforcement engine.
+
+  @param[in]  NewPolicy     Pointer to the incoming policy structure.
+
+  @retval     EFI_SUCCESS
+  @retval     EFI_INVALID_PARAMETER   NewPolicy is NULL or is internally inconsistent.
+  @retval     EFI_ALREADY_STARTED     An identical matching policy already exists.
+  @retval     EFI_WRITE_PROTECTED     The interface has been locked until the next reboot.
+  @retval     EFI_ABORTED             A calculation error has prevented this function from completing.
+  @retval     EFI_OUT_OF_RESOURCES    Cannot grow the table to hold any more policies.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *REGISTER_VARIABLE_POLICY)(
+  IN VARIABLE_POLICY_ENTRY *PolicyEntry
+  );
+
+/**
+  This API function will dump the entire contents of the variable policy table.
+
+  Similar to GetVariable, the first call can be made with a 0 size and it will return
+  the size of the buffer required to hold the entire table.
+
+  @param[out]     Policy  Pointer to the policy buffer. Can be NULL if Size is 0.
+  @param[in,out]  Size    On input, the size of the output buffer. On output, the size
+                          of the data returned.
+
+  @retval     EFI_SUCCESS             Policy data is in the output buffer and Size has been updated.
+  @retval     EFI_INVALID_PARAMETER   Size is NULL, or Size is non-zero and Policy is NULL.
+  @retval     EFI_BUFFER_TOO_SMALL    Size is insufficient to hold policy. Size updated with required size.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *DUMP_VARIABLE_POLICY)(
+  IN OUT UINT8  *Policy,
+  IN OUT UINT32 *Size
+  );
+
+/**
+  This API function locks the interface so that no more policy updates
+  can be performed or changes made to the enforcement until the next boot.
+
+  @retval     EFI_SUCCESS
+  @retval     Others        An error has prevented this command from completing.
+
+**/
+typedef
+EFI_STATUS
+(EFIAPI *LOCK_VARIABLE_POLICY)(
+  VOID
+  );
+
+typedef struct {
+  UINT64                     Revision;
+  DISABLE_VARIABLE_POLICY    DisableVariablePolicy;
+  IS_VARIABLE_POLICY_ENABLED IsVariablePolicyEnabled;
+  REGISTER_VARIABLE_POLICY   RegisterVariablePolicy;
+  DUMP_VARIABLE_POLICY       DumpVariablePolicy;
+  LOCK_VARIABLE_POLICY       LockVariablePolicy;
+} _VARIABLE_POLICY_PROTOCOL;
+
+typedef _VARIABLE_POLICY_PROTOCOL VARIABLE_POLICY_PROTOCOL;
+
+extern EFI_GUID gVariablePolicyProtocolGuid;
+
+#endif
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 4f44af694862..f74fea00b6e7 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -8,7 +8,7 @@
 # Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
 # (C) Copyright 2016 - 2019 Hewlett Packard Enterprise Development LP<BR>
 # Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
-# Copyright (c) 2016, Microsoft Corporation<BR>
+# Copyright (c) Microsoft Corporation.<BR>
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
 ##
@@ -624,6 +624,9 @@
 #   0x80000006 | Incorrect error code provided.
 #
 
+  ## Include/Protocol/VariablePolicy.h
+  gVariablePolicyProtocolGuid = { 0x81D1675C, 0x86F6, 0x48DF, { 0xBD, 0x95, 0x9A, 0x6E, 0x4F, 0x09, 0x25, 0xC3 } }
+
 [PcdsFeatureFlag]
   ## Indicates if the platform can support update capsule across a system reset.<BR><BR>
   #   TRUE  - Supports update capsule across a system reset.<BR>
@@ -1129,6 +1132,15 @@
   # @Prompt Variable storage size.
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableStoreSize|0x10000|UINT32|0x30000005
 
+  ## Toggle for whether the VariablePolicy engine should allow disabling.
+  # The engine is enabled at power-on, but the interface allows the platform to
+  # disable enforcement for servicing flexibility. If this PCD is disabled, it will block the ability to
+  # disable the enforcement and VariablePolicy enforcement will always be ON.
+  #   TRUE - VariablePolicy can be disabled by request through the interface (until interface is locked)
+  #   FALSE - VariablePolicy interface will not accept requests to disable and is ALWAYS ON
+  # @Prompt Allow VariablePolicy enforcement to be disabled.
+  gEfiMdeModulePkgTokenSpaceGuid.PcdAllowVariablePolicyEnforcementDisable|FALSE|BOOLEAN|0x30000020
+
   ## FFS filename to find the ACPI tables.
   # @Prompt FFS name of ACPI tables storage.
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiTableStorageFile|{ 0x25, 0x4e, 0x37, 0x7e, 0x01, 0x8e, 0xee, 0x4f, 0x87, 0xf2, 0x39, 0xc, 0x23, 0xc6, 0x6, 0xcd }|VOID*|0x30000016
-- 
2.16.3.windows.1