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**/
33STATIC
34BOOLEAN
35IsEntryPointStructureValid (
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**/
65SMBIOS_TABLE_ENTRY_POINT *
66GetXenSmbiosTables (
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}
99