OvmfPkg: Replace BSD License with BSD+Patent License

[mirror_edk2.git] / OvmfPkg / PlatformDxe / PlatformConfig.c

/** @file\r
\r
  Utility functions for serializing (persistently storing) and deserializing\r
  OVMF's platform configuration.\r
\r
  Copyright (C) 2014, Red Hat, Inc.\r
\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include <Library/BaseMemoryLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/MemoryAllocationLib.h>\r
#include <Library/UefiLib.h>\r
#include <Library/UefiRuntimeServicesTableLib.h>\r
#include <Guid/OvmfPlatformConfig.h>\r
\r
#include "PlatformConfig.h"\r
\r
//\r
// Name of the UEFI variable that we use for persistent storage.\r
//\r
STATIC CHAR16 mVariableName[] = L"PlatformConfig";\r
\r
\r
/**\r
  Serialize and persistently save platform configuration.\r
\r
  @param[in] PlatformConfig  The platform configuration to serialize and save.\r
\r
  @return  Status codes returned by gRT->SetVariable().\r
**/\r
EFI_STATUS\r
EFIAPI\r
PlatformConfigSave (\r
  IN PLATFORM_CONFIG *PlatformConfig\r
  )\r
{\r
  EFI_STATUS Status;\r
\r
  //\r
  // We could implement any kind of translation here, as part of serialization.\r
  // For example, we could expose the platform configuration in separate\r
  // variables with human-readable contents, allowing other tools to access\r
  // them more easily. For now, just save a binary dump.\r
  //\r
  Status = gRT->SetVariable (mVariableName, &gOvmfPlatformConfigGuid,\r
                  EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS |\r
                    EFI_VARIABLE_RUNTIME_ACCESS,\r
                  sizeof *PlatformConfig, PlatformConfig);\r
  return Status;\r
}\r
\r
\r
/**\r
  Load and deserialize platform configuration.\r
\r
  When the function fails, output parameters are indeterminate.\r
\r
  @param[out] PlatformConfig    The platform configuration to receive the\r
                                loaded data.\r
\r
  @param[out] OptionalElements  This bitmap describes the presence of optional\r
                                configuration elements that have been loaded.\r
                                PLATFORM_CONFIG_F_DOWNGRADE means that some\r
                                unknown elements, present in the wire format,\r
                                have been ignored.\r
\r
  @retval  EFI_SUCCESS         Loading & deserialization successful.\r
  @return                      Error codes returned by GetVariable2().\r
**/\r
EFI_STATUS\r
EFIAPI\r
PlatformConfigLoad (\r
  OUT PLATFORM_CONFIG *PlatformConfig,\r
  OUT UINT64          *OptionalElements\r
  )\r
{\r
  VOID       *Data;\r
  UINTN      DataSize;\r
  EFI_STATUS Status;\r
\r
  //\r
  // Any translation done in PlatformConfigSave() would have to be mirrored\r
  // here. For now, just load the binary dump.\r
  //\r
  // Versioning of the binary wire format is implemented based on size\r
  // (only incremental changes, ie. new fields), and on GUID.\r
  // (Incompatible changes require a GUID change.)\r
  //\r
  Status = GetVariable2 (mVariableName, &gOvmfPlatformConfigGuid, &Data,\r
             &DataSize);\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  *OptionalElements = 0;\r
  if (DataSize > sizeof *PlatformConfig) {\r
    //\r
    // Handle firmware downgrade -- keep only leading part.\r
    //\r
    CopyMem (PlatformConfig, Data, sizeof *PlatformConfig);\r
    *OptionalElements |= PLATFORM_CONFIG_F_DOWNGRADE;\r
  } else {\r
    CopyMem (PlatformConfig, Data, DataSize);\r
\r
    //\r
    // Handle firmware upgrade -- zero out missing fields.\r
    //\r
    ZeroMem ((UINT8 *)PlatformConfig + DataSize,\r
      sizeof *PlatformConfig - DataSize);\r
  }\r
\r
  //\r
  // Based on DataSize, report the optional features that we recognize.\r
  //\r
  if (DataSize >= (OFFSET_OF (PLATFORM_CONFIG, VerticalResolution) +\r
                   sizeof PlatformConfig->VerticalResolution)) {\r
    *OptionalElements |= PLATFORM_CONFIG_F_GRAPHICS_RESOLUTION;\r
  }\r
\r
  FreePool (Data);\r
  return EFI_SUCCESS;\r
}\r