OvmfPkg/SmbiosPlatformDxe/X86Xen.c

   1 /** @file
   2   Detect Xen hvmloader SMBIOS data for usage by OVMF.
   3
   4   Copyright (c) 2011, Bei Guan <gbtju85@gmail.com>
   5   Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
   6
   7   This program and the accompanying materials
   8   are licensed and made available under the terms and conditions of the BSD License
   9   which accompanies this distribution.  The full text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include "SmbiosPlatformDxe.h"
  18 #include <Library/HobLib.h>
  19 #include <Guid/XenInfo.h>
  20
  21 #define XEN_SMBIOS_PHYSICAL_ADDRESS       0x000EB000
  22 #define XEN_SMBIOS_PHYSICAL_END           0x000F0000
  23
  24 /**
  25   Validates the SMBIOS entry point structure
  26
  27   @param  EntryPointStructure  SMBIOS entry point structure
  28
  29   @retval TRUE   The entry point structure is valid
  30   @retval FALSE  The entry point structure is not valid
  31
  32 **/
  33 STATIC
  34 BOOLEAN
  35 IsEntryPointStructureValid (
  36   IN SMBIOS_TABLE_ENTRY_POINT  *EntryPointStructure
  37   )
  38 {
  39   UINTN                     Index;
  40   UINT8                     Length;
  41   UINT8                     Checksum;
  42   UINT8                     *BytePtr;
  43
  44   BytePtr = (UINT8*) EntryPointStructure;
  45   Length = EntryPointStructure->EntryPointLength;
  46   Checksum = 0;
  47
  48   for (Index = 0; Index < Length; Index++) {
  49     Checksum = Checksum + (UINT8) BytePtr[Index];
  50   }
  51
  52   if (Checksum != 0) {
  53     return FALSE;
  54   } else {
  55     return TRUE;
  56   }
  57 }
  58
  59 /**
  60   Locates the Xen SMBIOS data if it exists
  61
  62   @return SMBIOS_TABLE_ENTRY_POINT   Address of Xen SMBIOS data
  63
  64 **/
  65 SMBIOS_TABLE_ENTRY_POINT *
  66 GetXenSmbiosTables (
  67   VOID
  68   )
  69 {
  70   UINT8                     *XenSmbiosPtr;
  71   SMBIOS_TABLE_ENTRY_POINT  *XenSmbiosEntryPointStructure;
  72   EFI_HOB_GUID_TYPE         *GuidHob;
  73
  74   //
  75   // See if a XenInfo HOB is available
  76   //
  77   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
  78   if (GuidHob == NULL) {
  79     return NULL;
  80   }
  81
  82   for (XenSmbiosPtr = (UINT8*)(UINTN) XEN_SMBIOS_PHYSICAL_ADDRESS;
  83        XenSmbiosPtr < (UINT8*)(UINTN) XEN_SMBIOS_PHYSICAL_END;
  84        XenSmbiosPtr += 0x10) {
  85
  86     XenSmbiosEntryPointStructure = (SMBIOS_TABLE_ENTRY_POINT *) XenSmbiosPtr;
  87
  88     if (!AsciiStrnCmp ((CHAR8 *) XenSmbiosEntryPointStructure->AnchorString, "_SM_", 4) &&
  89         !AsciiStrnCmp ((CHAR8 *) XenSmbiosEntryPointStructure->IntermediateAnchorString, "_DMI_", 5) &&
  90         IsEntryPointStructureValid (XenSmbiosEntryPointStructure)) {
  91
  92       return XenSmbiosEntryPointStructure;
  93
  94     }
  95   }
  96
  97   return NULL;
  98 }