[PATCH v1 3/6] MdeModulePkg: Map persistent (NV) memory

[Sami Mujawar <sami.mujawar@arm.com>]

Some platforms are able to preserve a memory range across
system resets. This memory can be used for the Non-Volatile
variables storage. The PcdEmuVariableNvStoreReserved is
used to specify this option.

This patch enables mapping of this Non-Volatile memory range
as runtime memory so that the variable storage is accessible
post ExitBootServices.

Also added PcdMapEmuVariableNvStoreReserved to select if the
memory region described by PcdMapEmuVariableNvStoreReserved
should be mapped by the Variable Emulation driver.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---
The changes can be seen at https://github.com/samimujawar/edk2/commit/a4fbf2336578546031920337239f41544a3a130e

Notes:
    v1:
    - Add support for mapping memory used for Non-Volatile variable   [SAMI]
      storage as runtime memory.

 MdeModulePkg/MdeModulePkg.dec                                           |  9 +++
 MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariable.c             | 77 +++++++++++++++++++-
 MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariableRuntimeDxe.inf |  6 ++
 3 files changed, 90 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 6037504fa789d4ca96d45bf3a776dd77bc17a909..077d3682371e1d44b0c86f922f80536080403e52 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -8,6 +8,7 @@
 # (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
 # Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
 # Copyright (c) 2016, Microsoft Corporation<BR>
+# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
 # This program and the accompanying materials are licensed and made available under
 # the terms and conditions of the BSD License that accompanies this distribution.
 # The full text of the license may be found at
@@ -1592,6 +1593,14 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
   # @Prompt Reserved memory range for EMU variable NV storage.
   gEfiMdeModulePkgTokenSpaceGuid.PcdEmuVariableNvStoreReserved|0|UINT64|0x40000008
 
+  ## Indicates if the reserved memory range for the EMU Variable driver's
+  #  NV Variable Store should be mapped by the driver. The memory range size
+  #  must be PcdVariableStoreSize.
+  #   TRUE  - Map the memory as persistent runtime memory.<BR>
+  #   FALSE - Do not map the memory.<BR>
+  # @Prompt Map persistent memory range for EMU variable NV storage.
+  gEfiMdeModulePkgTokenSpaceGuid.PcdMapEmuVariableNvStoreReserved|FALSE|BOOLEAN|0x4000000f
+
   ## This PCD defines the times to print hello world string.
   #  This PCD is a sample to explain UINT32 PCD usage.
   # @Prompt HellowWorld print times.
diff --git a/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariable.c b/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariable.c
index 1bcf931b96a670ab1fc66cd66f9d88d68f363e7f..e103a340aea9394d9ff146efa5581d3180c45035 100644
--- a/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariable.c
+++ b/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariable.c
@@ -4,6 +4,7 @@
   The nonvolatile variable space doesn't exist.
 
 Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
@@ -14,6 +15,8 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 **/
 
+#include <Library/DxeServicesTableLib.h>
+
 #include "Variable.h"
 
 ///
@@ -1643,11 +1646,13 @@ EmuQueryVariableInfo (
 
   This function allocates memory space for variable store area and initializes its attributes.
 
+  @param  ImageHandle    The Image handle of this driver.
   @param  VolatileStore  Indicates if the variable store is volatile.
 
 **/
 EFI_STATUS
 InitializeVariableStore (
+  IN  EFI_HANDLE            ImageHandle,
   IN  BOOLEAN               VolatileStore
   )
 {
@@ -1693,6 +1698,74 @@ InitializeVariableStore (
     VariableStore =
       (VARIABLE_STORE_HEADER *)(VOID*)(UINTN)
         PcdGet64 (PcdEmuVariableNvStoreReserved);
+
+    if (PcdGetBool (PcdMapEmuVariableNvStoreReserved)) {
+      DEBUG((
+        DEBUG_INFO,
+        "Initializing NV Variable Store at %p, Size = 0x%x\n",
+        VariableStore, PcdGet32 (PcdVariableStoreSize)
+        ));
+
+      // Declare the NV Storage as persistent EFI_MEMORY_RUNTIME memory
+      Status = gDS->AddMemorySpace (
+                      EfiGcdMemoryTypePersistent,
+                      (EFI_PHYSICAL_ADDRESS)VariableStore,
+                      PcdGet32 (PcdVariableStoreSize),
+                      EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
+                      );
+      if (EFI_ERROR (Status)) {
+        DEBUG ((
+          DEBUG_ERROR, "Failed to add memory space. Status = %r\n",
+          Status
+          ));
+        return Status;
+      }
+
+      Status = gDS->AllocateMemorySpace (
+                      EfiGcdAllocateAddress,
+                      EfiGcdMemoryTypePersistent,
+                      0,
+                      PcdGet32 (PcdVariableStoreSize),
+                      (EFI_PHYSICAL_ADDRESS*)&VariableStore,
+                      ImageHandle,
+                      NULL
+                      );
+      if (EFI_ERROR (Status)) {
+        DEBUG ((
+          DEBUG_ERROR,
+          "Failed to allocate memory space. Status = %r\n",
+          Status
+          ));
+        gDS->RemoveMemorySpace (
+               (EFI_PHYSICAL_ADDRESS)VariableStore,
+               PcdGet32 (PcdVariableStoreSize)
+               );
+        return Status;
+      }
+
+      Status = gDS->SetMemorySpaceAttributes (
+                      (EFI_PHYSICAL_ADDRESS)VariableStore,
+                      PcdGet32 (PcdVariableStoreSize),
+                      EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
+                      );
+      if (EFI_ERROR (Status)) {
+        DEBUG ((
+          DEBUG_ERROR,
+          "Failed to set memory attributes. Status = %r\n",
+          Status
+          ));
+        gDS->FreeMemorySpace (
+               (EFI_PHYSICAL_ADDRESS)VariableStore,
+               PcdGet32 (PcdVariableStoreSize)
+               );
+        gDS->RemoveMemorySpace (
+               (EFI_PHYSICAL_ADDRESS)VariableStore,
+               PcdGet32 (PcdVariableStoreSize)
+               );
+        return Status;
+      }
+    }
+
     if (
          (VariableStore->Size == PcdGet32 (PcdVariableStoreSize)) &&
          (VariableStore->Format == VARIABLE_STORE_FORMATTED) &&
@@ -1806,7 +1879,7 @@ VariableCommonInitialize (
   //
   // Intialize volatile variable store
   //
-  Status = InitializeVariableStore (TRUE);
+  Status = InitializeVariableStore (ImageHandle, TRUE);
   if (EFI_ERROR (Status)) {
     FreePool(mVariableModuleGlobal);
     return Status;
@@ -1814,7 +1887,7 @@ VariableCommonInitialize (
   //
   // Intialize non volatile variable store
   //
-  Status = InitializeVariableStore (FALSE);
+  Status = InitializeVariableStore (ImageHandle, FALSE);
 
   return Status;
 }
diff --git a/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariableRuntimeDxe.inf b/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariableRuntimeDxe.inf
index 12d52dd130e317c7ed041cf144805b8547bfc62b..1b5902749e1806143e92ccc2009a7512d57b940b 100644
--- a/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariableRuntimeDxe.inf
+++ b/MdeModulePkg/Universal/Variable/EmuRuntimeDxe/EmuVariableRuntimeDxe.inf
@@ -5,6 +5,7 @@
 # four EFI_RUNTIME_SERVICES: SetVariable, GetVariable, GetNextVariableName and QueryVariableInfo.
 #
 # Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
 #
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions of the BSD License
@@ -53,6 +54,7 @@ [LibraryClasses]
   BaseMemoryLib
   HobLib
   PcdLib
+  DxeServicesTableLib
 
 [Protocols]
   gEfiVariableArchProtocolGuid                  ## PRODUCES
@@ -77,10 +79,14 @@ [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxHardwareErrorVariableSize    ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableStoreSize               ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdHwErrStorageSize                ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdMapEmuVariableNvStoreReserved   ## CONSUMES
 
 [FeaturePcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdVariableCollectStatistics   ## CONSUMES # statistic the information of variable.
 
+[Depex.common.DXE_RUNTIME_DRIVER]
+  gEfiCpuArchProtocolGuid
+
 [Depex]
   TRUE
 
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'