OvmfPkg: SmbiosPlatformDxe: eliminate duplicate entry point validation

[mirror_edk2.git] / OvmfPkg / Library / SmbiosVersionLib / DetectSmbiosVersionLib.c

/** @file\r
\r
  A hook-in library for MdeModulePkg/Universal/SmbiosDxe, in order to set\r
  gEfiMdeModulePkgTokenSpaceGuid.PcdSmbiosVersion (and possibly other PCDs)\r
  just before SmbiosDxe consumes them.\r
\r
  Copyright (C) 2013, 2015, Red Hat, Inc.\r
  Copyright (c) 2008 - 2012, Intel Corporation. All rights reserved.<BR>\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License which accompanies this\r
  distribution. The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include <IndustryStandard/SmBios.h>\r
\r
#include <Base.h>\r
#include <Library/BaseMemoryLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/PcdLib.h>\r
#include <Library/QemuFwCfgLib.h>\r
\r
typedef union {\r
  SMBIOS_TABLE_ENTRY_POINT     V2;\r
} QEMU_SMBIOS_ANCHOR;\r
\r
RETURN_STATUS\r
EFIAPI\r
DetectSmbiosVersion (\r
  VOID\r
  )\r
{\r
  FIRMWARE_CONFIG_ITEM Anchor, Tables;\r
  UINTN                AnchorSize, TablesSize;\r
  QEMU_SMBIOS_ANCHOR   QemuAnchor;\r
  UINT16               SmbiosVersion;\r
\r
  if (PcdGetBool (PcdQemuSmbiosValidated)) {\r
    //\r
    // Some other module, linked against this library, has already performed\r
    // the task at hand. This should never happen, but it's easy to handle;\r
    // just exit early.\r
    //\r
    return RETURN_SUCCESS;\r
  }\r
\r
  if (RETURN_ERROR (QemuFwCfgFindFile (\r
                      "etc/smbios/smbios-anchor", &Anchor, &AnchorSize)) ||\r
      RETURN_ERROR (QemuFwCfgFindFile (\r
                      "etc/smbios/smbios-tables", &Tables, &TablesSize)) ||\r
      TablesSize == 0) {\r
    return RETURN_SUCCESS;\r
  }\r
\r
  QemuFwCfgSelectItem (Anchor);\r
\r
  switch (AnchorSize) {\r
  case sizeof QemuAnchor.V2:\r
    QemuFwCfgReadBytes (AnchorSize, &QemuAnchor);\r
\r
    if (QemuAnchor.V2.MajorVersion != 2 ||\r
        QemuAnchor.V2.TableLength != TablesSize ||\r
        CompareMem (QemuAnchor.V2.AnchorString, "_SM_", 4) != 0 ||\r
        CompareMem (QemuAnchor.V2.IntermediateAnchorString, "_DMI_", 5) != 0) {\r
      return RETURN_SUCCESS;\r
    }\r
    SmbiosVersion = (UINT16)(QemuAnchor.V2.MajorVersion << 8 |\r
                             QemuAnchor.V2.MinorVersion);\r
    break;\r
\r
  default:\r
    return RETURN_SUCCESS;\r
  }\r
\r
  DEBUG ((EFI_D_INFO, "%a: SMBIOS version from QEMU: 0x%04x\n", __FUNCTION__,\r
    SmbiosVersion));\r
  PcdSet16 (PcdSmbiosVersion, SmbiosVersion);\r
\r
  //\r
  // SMBIOS platform drivers can now fetch and install\r
  // "etc/smbios/smbios-tables" from QEMU.\r
  //\r
  PcdSetBool (PcdQemuSmbiosValidated, TRUE);\r
  return RETURN_SUCCESS;\r
}\r