OvmfPkg: QemuFwCfgLib: extract stateful implementation

The current implementation of QemuFwCfgLib is:
- stateful
- implicitly initialized in the library constructor.

OVMF's SEC runs from read-only memory/flash. When the library is linked
into a SEC binary (which currently never happens), the
"mQemuFwCfgSupported" global variable becomes read-only, making the
library non-functional.

Extract the stateful, implicitly initialized library implementation into a
separate file, making room for a stateless, explicitly queried
implementation that's usable in SEC. Restrict the stateful implementation
to the current, non-SEC clients.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15045 6f19259b-4bc3-4df7-8a09-765794883524

3 files changed, 97 insertions, 75 deletions

diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
index 985b383c26..3c5963f31b 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
@@ -22,8 +22,6 @@
 #include <Library/MemoryAllocationLib.h>

 #include <Library/UefiBootServicesTableLib.h>

 

-STATIC BOOLEAN mQemuFwCfgSupported = FALSE;

-

 

 /**

   Reads an 8-bit I/O port fifo into a block of memory.

@@ -79,26 +77,6 @@ IoWriteFifo8 (
 

 

 /**

-  Returns a boolean indicating if the firmware configuration interface

-  is available or not.

-

-  This function may change fw_cfg state.

-

-  @retval    TRUE   The interface is available

-  @retval    FALSE  The interface is not available

-

-**/

-BOOLEAN

-EFIAPI

-QemuFwCfgIsAvailable (

-  VOID

-  )

-{

-  return InternalQemuFwCfgIsAvailable ();

-}

-

-

-/**

   Selects a firmware configuration item for reading.

   

   Following this call, any data read from this item will start from

@@ -265,39 +243,6 @@ QemuFwCfgRead64 (
 }

 

 

-RETURN_STATUS

-EFIAPI

-QemuFwCfgInitialize (

-  VOID

-  )

-{

-  UINT32 Signature;

-  UINT32 Revision;

-

-  //

-  // Enable the access routines while probing to see if it is supported.

-  //

-  mQemuFwCfgSupported = TRUE;

-

-  QemuFwCfgSelectItem (QemuFwCfgItemSignature);

-  Signature = QemuFwCfgRead32 ();

-  DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));

-  QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);

-  Revision = QemuFwCfgRead32 ();

-  DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));

-  if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||

-      (Revision < 1)

-     ) {

-    DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));

-    mQemuFwCfgSupported = FALSE;

-    return RETURN_SUCCESS;

-  }

-

-  DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));

-  return RETURN_SUCCESS;

-}

-

-

 /**

   Find the configuration item corresponding to the firmware configuration file.

 

@@ -349,22 +294,3 @@ QemuFwCfgFindFile (
 

   return RETURN_NOT_FOUND;

 }

-

-

-/**

-  Returns a boolean indicating if the firmware configuration interface is

-  available for library-internal purposes.

-

-  This function never changes fw_cfg state.

-

-  @retval    TRUE   The interface is available internally.

-  @retval    FALSE  The interface is not available internally.

-**/

-BOOLEAN

-EFIAPI

-InternalQemuFwCfgIsAvailable (

-  VOID

-  )

-{

-  return mQemuFwCfgSupported;

-}

diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
index e6910c76bb..071737edef 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
@@ -1,5 +1,8 @@
 ## @file

 #

+#  Stateful, implicitly initialized fw_cfg library.

+#

+#  Copyright (C) 2013, Red Hat, Inc.

 #  Copyright (c) 2008 - 2012, Intel Corporation. All rights reserved.<BR>

 #

 #  This program and the accompanying materials

@@ -18,7 +21,7 @@
   FILE_GUID                      = fdd53716-31e1-4acc-9007-8bd5d877c96f

   MODULE_TYPE                    = BASE

   VERSION_STRING                 = 1.0

-  LIBRARY_CLASS                  = QemuFwCfgLib

+  LIBRARY_CLASS                  = QemuFwCfgLib|PEIM DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SMM_DRIVER

 

   CONSTRUCTOR                    = QemuFwCfgInitialize

 

@@ -30,6 +33,7 @@
 

 [Sources]

   QemuFwCfgLib.c

+  QemuFwCfgPeiDxe.c

 

 [Sources.IA32]

   Ia32/IoLibExAsm.asm

diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c
new file mode 100644
index 0000000000..f693cff29e
--- /dev/null
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c
@@ -0,0 +1,92 @@
+/** @file

+

+  Stateful and implicitly initialized fw_cfg library implementation.

+

+  Copyright (C) 2013, Red Hat, Inc.

+  Copyright (c) 2011 - 2013, Intel Corporation. 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

+  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/DebugLib.h>

+#include <Library/QemuFwCfgLib.h>

+

+STATIC BOOLEAN mQemuFwCfgSupported = FALSE;

+

+

+/**

+  Returns a boolean indicating if the firmware configuration interface

+  is available or not.

+

+  This function may change fw_cfg state.

+

+  @retval    TRUE   The interface is available

+  @retval    FALSE  The interface is not available

+

+**/

+BOOLEAN

+EFIAPI

+QemuFwCfgIsAvailable (

+  VOID

+  )

+{

+  return InternalQemuFwCfgIsAvailable ();

+}

+

+

+RETURN_STATUS

+EFIAPI

+QemuFwCfgInitialize (

+  VOID

+  )

+{

+  UINT32 Signature;

+  UINT32 Revision;

+

+  //

+  // Enable the access routines while probing to see if it is supported.

+  //

+  mQemuFwCfgSupported = TRUE;

+

+  QemuFwCfgSelectItem (QemuFwCfgItemSignature);

+  Signature = QemuFwCfgRead32 ();

+  DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));

+  QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);

+  Revision = QemuFwCfgRead32 ();

+  DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));

+  if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||

+      (Revision < 1)

+     ) {

+    DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));

+    mQemuFwCfgSupported = FALSE;

+    return RETURN_SUCCESS;

+  }

+

+  DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));

+  return RETURN_SUCCESS;

+}

+

+

+/**

+  Returns a boolean indicating if the firmware configuration interface is

+  available for library-internal purposes.

+

+  This function never changes fw_cfg state.

+

+  @retval    TRUE   The interface is available internally.

+  @retval    FALSE  The interface is not available internally.

+**/

+BOOLEAN

+EFIAPI

+InternalQemuFwCfgIsAvailable (

+  VOID

+  )

+{

+  return mQemuFwCfgSupported;

+}