OvmfPkg/SmbiosPlatformDxe/Qemu.c

   1 /** @file
   2   Find and extract QEMU SMBIOS data from fw_cfg.
   3
   4   Copyright (C) 2014, Gabriel L. Somlo <somlo@cmu.edu>
   5
   6   This program and the accompanying materials are licensed and made
   7   available under the terms and conditions of the BSD License which
   8   accompanies this distribution.   The full text of the license may
   9   be found at http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 **/
  14
  15 #include "SmbiosPlatformDxe.h"
  16 #include <Library/QemuFwCfgLib.h>
  17 #include <Library/MemoryAllocationLib.h>
  18
  19 /**
  20   Locates and extracts the QEMU SMBIOS data if present in fw_cfg
  21
  22   @return                 Address of extracted QEMU SMBIOS data
  23
  24 **/
  25 UINT8 *
  26 GetQemuSmbiosTables (
  27   VOID
  28   )
  29 {
  30   SMBIOS_TABLE_ENTRY_POINT QemuAnchor;
  31   FIRMWARE_CONFIG_ITEM     Anchor, Tables;
  32   UINTN                    AnchorSize, TablesSize;
  33   UINT8                    *QemuTables;
  34
  35   if (EFI_ERROR (QemuFwCfgFindFile (
  36                    "etc/smbios/smbios-anchor", &Anchor, &AnchorSize)) ||
  37       EFI_ERROR (QemuFwCfgFindFile (
  38                    "etc/smbios/smbios-tables", &Tables, &TablesSize)) ||
  39       AnchorSize != sizeof (QemuAnchor) ||
  40       TablesSize == 0) {
  41     return NULL;
  42   }
  43
  44   //
  45   // We copy the entry point structure to perform some additional checks,
  46   // but discard it upon return.
  47   //
  48   QemuFwCfgSelectItem (Anchor);
  49   QemuFwCfgReadBytes (AnchorSize, &QemuAnchor);
  50
  51   if (AsciiStrnCmp ((CHAR8 *)QemuAnchor.AnchorString, "_SM_", 4) ||
  52       AsciiStrnCmp ((CHAR8 *)QemuAnchor.IntermediateAnchorString, "_DMI_", 5) ||
  53       TablesSize != QemuAnchor.TableLength) {
  54     return NULL;
  55   }
  56
  57   QemuTables = AllocatePool (TablesSize);
  58   if (QemuTables == NULL) {
  59     return NULL;
  60   }
  61
  62   QemuFwCfgSelectItem (Tables);
  63   QemuFwCfgReadBytes (TablesSize, QemuTables);
  64
  65   return QemuTables;
  66 }