An OVMF binary built with

  -D SMM_REQUIRE

or with

  -D MEM_VARSTORE_EMU_ENABLE=FALSE

requires flash to be present at the expected (build-time determined)
location; falling back to the emulated varstore is not possible.

In such builds, we can replace the settings of the
- varstore,
- FTW working block,
- and FTW spare area
address PCDs in QemuFlashFvbServicesRuntimeDxe with identical settings in
a new plug-in (NULL class) library, to be linked into variable-related
PEIMs.

This will enable such builds to access variables during the PEI phase,
without dynamic flash detection and without ordering constraints against
other PEIMs.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.inf | 48 ++++++++++++++++++
 OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.c   | 53 ++++++++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.inf b/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.inf
new file mode 100644
index 000000000000..f79194f80de9
--- /dev/null
+++ b/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.inf
@@ -0,0 +1,48 @@
+## @file
+#
+# A hook-in library for variable-related PEIMs, in order to set
+# - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase64,
+# - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase,
+# - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase,
+# from their gUefiOvmfPkgTokenSpaceGuid counterparts, just before those PEIMs
+# consume them.
+#
+# Copyright (C) 2017, Red Hat, Inc.
+#
+# 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
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
+# WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = FlashNvStorageAddressLib
+  FILE_GUID                      = 5FF5A9F9-D01E-49EC-9A17-1682FC85122F
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = FlashNvStorageAddressLib|PEIM
+  CONSTRUCTOR                    = SetFlashNvStorageAddresses
+
+[Sources]
+  FlashNvStorageAddressLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  PcdLib
+
+[Pcd]
+  gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase
+  gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase
+  gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase64
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageFtwSpareBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageFtwWorkingBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageVariableBase
diff --git a/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.c b/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.c
new file mode 100644
index 000000000000..dc1280cc23f1
--- /dev/null
+++ b/OvmfPkg/Library/FlashNvStorageAddressLib/FlashNvStorageAddressLib.c
@@ -0,0 +1,53 @@
+/** @file
+
+  A hook-in library for variable-related PEIMs, in order to set
+  - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableBase64,
+  - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase,
+  - gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase,
+  from their gUefiOvmfPkgTokenSpaceGuid counterparts, just before those PEIMs
+  consume them.
+
+  Copyright (C) 2017, Red Hat, Inc.
+
+  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
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
+  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <Library/PcdLib.h>
+
+RETURN_STATUS
+EFIAPI
+SetFlashNvStorageAddresses (
+  VOID
+  )
+{
+  RETURN_STATUS PcdStatus;
+
+  PcdStatus = PcdSet64S (
+                PcdFlashNvStorageVariableBase64,
+                PcdGet32 (PcdOvmfFlashNvStorageVariableBase)
+                );
+  if (RETURN_ERROR (PcdStatus)) {
+    return PcdStatus;
+  }
+
+  PcdStatus = PcdSet32S (
+                PcdFlashNvStorageFtwWorkingBase,
+                PcdGet32 (PcdOvmfFlashNvStorageFtwWorkingBase)
+                );
+  if (RETURN_ERROR (PcdStatus)) {
+    return PcdStatus;
+  }
+
+  PcdStatus = PcdSet32S (
+                PcdFlashNvStorageFtwSpareBase,
+                PcdGet32 (PcdOvmfFlashNvStorageFtwSpareBase)
+                );
+  return PcdStatus;
+}
-- 
2.9.3


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