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   SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include "SmbiosPlatformDxe.h"
  12 #include <Library/HobLib.h>
  13 #include <Guid/XenInfo.h>
  14
  15 #define XEN_SMBIOS_PHYSICAL_ADDRESS       0x000EB000
  16 #define XEN_SMBIOS_PHYSICAL_END           0x000F0000
  17
  18 /**
  19   Validates the SMBIOS entry point structure
  20
  21   @param  EntryPointStructure  SMBIOS entry point structure
  22
  23   @retval TRUE   The entry point structure is valid
  24   @retval FALSE  The entry point structure is not valid
  25
  26 **/
  27 STATIC
  28 BOOLEAN
  29 IsEntryPointStructureValid (
  30   IN SMBIOS_TABLE_ENTRY_POINT  *EntryPointStructure
  31   )
  32 {
  33   UINTN                     Index;
  34   UINT8                     Length;
  35   UINT8                     Checksum;
  36   UINT8                     *BytePtr;
  37
  38   BytePtr = (UINT8*) EntryPointStructure;
  39   Length = EntryPointStructure->EntryPointLength;
  40   Checksum = 0;
  41
  42   for (Index = 0; Index < Length; Index++) {
  43     Checksum = Checksum + (UINT8) BytePtr[Index];
  44   }
  45
  46   if (Checksum != 0) {
  47     return FALSE;
  48   } else {
  49     return TRUE;
  50   }
  51 }
  52
  53 /**
  54   Locates the Xen SMBIOS data if it exists
  55
  56   @return SMBIOS_TABLE_ENTRY_POINT   Address of Xen SMBIOS data
  57
  58 **/
  59 SMBIOS_TABLE_ENTRY_POINT *
  60 GetXenSmbiosTables (
  61   VOID
  62   )
  63 {
  64   UINT8                     *XenSmbiosPtr;
  65   SMBIOS_TABLE_ENTRY_POINT  *XenSmbiosEntryPointStructure;
  66   EFI_HOB_GUID_TYPE         *GuidHob;
  67
  68   //
  69   // See if a XenInfo HOB is available
  70   //
  71   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
  72   if (GuidHob == NULL) {
  73     return NULL;
  74   }
  75
  76   for (XenSmbiosPtr = (UINT8*)(UINTN) XEN_SMBIOS_PHYSICAL_ADDRESS;
  77        XenSmbiosPtr < (UINT8*)(UINTN) XEN_SMBIOS_PHYSICAL_END;
  78        XenSmbiosPtr += 0x10) {
  79
  80     XenSmbiosEntryPointStructure = (SMBIOS_TABLE_ENTRY_POINT *) XenSmbiosPtr;
  81
  82     if (!AsciiStrnCmp ((CHAR8 *) XenSmbiosEntryPointStructure->AnchorString, "_SM_", 4) &&
  83         !AsciiStrnCmp ((CHAR8 *) XenSmbiosEntryPointStructure->IntermediateAnchorString, "_DMI_", 5) &&
  84         IsEntryPointStructureValid (XenSmbiosEntryPointStructure)) {
  85
  86       return XenSmbiosEntryPointStructure;
  87
  88     }
  89   }
  90
  91   return NULL;
  92 }