[PATCH 09/12] OvmfPkg/QemuFwCfgS3Lib: implement opcode APIs for PEI fw_cfg instance

[Laszlo Ersek <lersek@redhat.com>]

In the PEI fw_cfg instance:

- QemuFwCfgS3Enabled() queries S3 enablement via fw_cfg. This behavior is
  shared with the DXE fw_cfg instance, and the PEI fw_cfg instance already
  pulls in the function from "QemuFwCfgS3PeiDxe.c".

- If QemuFwCfgS3Enabled() returns TRUE, the client module is permitted to
  call QemuFwCfgS3TransferOwnership(). However, in the PEI phase we have
  no support for capturing ACPI S3 Boot Script opcodes, hence we return
  RETURN_UNSUPPORTED unconditionally. This behavior is unique to the PEI
  fw_cfg instance, so add the function to "QemuFwCfgS3Pei.c".

- Consequently, the QemuFwCfgS3WriteBytes(), QemuFwCfgS3ReadBytes(),
  QemuFwCfgS3SkipBytes(), and QemuFwCfgS3CheckValue() functions must never
  be called. (They could only be called from the client module's callback,
  but QemuFwCfgS3TransferOwnership() will never install such callback in
  the PEI fw_cfg instance -- see above.)

  This behavior is not unique to the PEI fw_cfg instance (it is shared
  with the Base Null instance), so pull in these functions from
  "QemuFwCfgS3BasePei.c".

Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=394
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf |  3 +
 OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Pei.c           | 85 ++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf b/OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf
index 2593af8e5b4c..890862076e81 100644
--- a/OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf
+++ b/OvmfPkg/Library/QemuFwCfgS3Lib/PeiQemuFwCfgS3LibFwCfg.inf
@@ -31,6 +31,8 @@ [Defines]
 #
 
 [Sources]
+  QemuFwCfgS3BasePei.c
+  QemuFwCfgS3Pei.c
   QemuFwCfgS3PeiDxe.c
 
 [Packages]
@@ -38,4 +40,5 @@ [Packages]
   OvmfPkg/OvmfPkg.dec
 
 [LibraryClasses]
+  DebugLib
   QemuFwCfgLib
diff --git a/OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Pei.c b/OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Pei.c
new file mode 100644
index 000000000000..77ed058884e1
--- /dev/null
+++ b/OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Pei.c
@@ -0,0 +1,85 @@
+/** @file
+  Limited functionality QemuFwCfgS3Lib instance, for PEI phase modules.
+
+  QemuFwCfgS3Enabled() queries S3 enablement via fw_cfg. Other library APIs
+  will report lack of support.
+
+  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/QemuFwCfgS3Lib.h>
+
+/**
+  Install the client module's FW_CFG_BOOT_SCRIPT_APPEND_FUNCTION callback for
+  when the production of ACPI S3 Boot Script opcodes becomes possible.
+
+  Take ownership of the client-provided Context, and pass it to the callback
+  function, when the latter is invoked.
+
+  Allocate scratch space for those ACPI S3 Boot Script opcodes to work upon
+  that the client will produce in the callback function.
+
+  @param[in] Append             FW_CFG_BOOT_SCRIPT_APPEND_FUNCTION to invoke
+                                when the production of ACPI S3 Boot Script
+                                opcodes becomes possible. Append() may be
+                                called immediately from
+                                QemuFwCfgS3TransferOwnership().
+
+  @param[in,out] Context        Client-provided data structure for the Append()
+                                callback function to consume.
+
+                                If Context points to dynamically allocated
+                                memory, then Append() must release it.
+
+                                If Context points to dynamically allocated
+                                memory, and QemuFwCfgS3TransferOwnership()
+                                returns successfully, then the caller of
+                                QemuFwCfgS3TransferOwnership() must neither
+                                dereference nor even evaluate Context any
+                                longer, as ownership of the referenced area has
+                                been transferred to Append().
+
+  @param[in] ScratchBufferSize  The size of the scratch buffer that will hold,
+                                in reserved memory, all client data read,
+                                written, and checked by the ACPI S3 Boot Script
+                                opcodes produced by Append().
+
+  @retval RETURN_UNSUPPORTED       The library instance does not support this
+                                   function.
+
+  @retval RETURN_NOT_FOUND         The fw_cfg DMA interface to QEMU is
+                                   unavailable.
+
+  @retval RETURN_BAD_BUFFER_SIZE   ScratchBufferSize is too large.
+
+  @retval RETURN_OUT_OF_RESOURCES  Memory allocation failed.
+
+  @retval RETURN_SUCCESS           Append() has been installed, and the
+                                   ownership of Context has been transferred.
+                                   Reserved memory has been allocated for the
+                                   scratch buffer.
+
+                                   A successful invocation of
+                                   QemuFwCfgS3TransferOwnership() cannot be
+                                   rolled back.
+
+  @return                          Error codes from underlying functions.
+**/
+EFIAPI
+RETURN_STATUS
+QemuFwCfgS3TransferOwnership (
+  IN     FW_CFG_BOOT_SCRIPT_APPEND_FUNCTION *Append,
+  IN OUT VOID                               *Context,          OPTIONAL
+  IN     UINTN                              ScratchBufferSize
+  )
+{
+  return RETURN_UNSUPPORTED;
+}
-- 
2.9.3