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1 | /** @file\r |
2 | \r | |
3 | Utility functions for serializing (persistently storing) and deserializing\r | |
4 | OVMF's platform configuration.\r | |
5 | \r | |
6 | Copyright (C) 2014, Red Hat, Inc.\r | |
7 | \r | |
8 | This program and the accompanying materials are licensed and made available\r | |
9 | under the terms and conditions of the BSD License which accompanies this\r | |
10 | distribution. The full text of the license may be found at\r | |
11 | http://opensource.org/licenses/bsd-license.php\r | |
12 | \r | |
13 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r | |
14 | WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
15 | \r | |
16 | **/\r | |
17 | \r | |
18 | #include <Library/BaseMemoryLib.h>\r | |
19 | #include <Library/DebugLib.h>\r | |
20 | #include <Library/MemoryAllocationLib.h>\r | |
21 | #include <Library/UefiLib.h>\r | |
22 | #include <Library/UefiRuntimeServicesTableLib.h>\r | |
23 | #include <Guid/OvmfPlatformConfig.h>\r | |
24 | \r | |
25 | #include "PlatformConfig.h"\r | |
26 | \r | |
27 | //\r | |
28 | // Name of the UEFI variable that we use for persistent storage.\r | |
29 | //\r | |
30 | STATIC CHAR16 mVariableName[] = L"PlatformConfig";\r | |
31 | \r | |
32 | \r | |
33 | /**\r | |
34 | Serialize and persistently save platform configuration.\r | |
35 | \r | |
36 | @param[in] PlatformConfig The platform configuration to serialize and save.\r | |
37 | \r | |
38 | @return Status codes returned by gRT->SetVariable().\r | |
39 | **/\r | |
40 | EFI_STATUS\r | |
41 | EFIAPI\r | |
42 | PlatformConfigSave (\r | |
43 | IN PLATFORM_CONFIG *PlatformConfig\r | |
44 | )\r | |
45 | {\r | |
46 | EFI_STATUS Status;\r | |
47 | \r | |
48 | //\r | |
49 | // We could implement any kind of translation here, as part of serialization.\r | |
50 | // For example, we could expose the platform configuration in separate\r | |
51 | // variables with human-readable contents, allowing other tools to access\r | |
52 | // them more easily. For now, just save a binary dump.\r | |
53 | //\r | |
54 | Status = gRT->SetVariable (mVariableName, &gOvmfPlatformConfigGuid,\r | |
55 | EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS |\r | |
56 | EFI_VARIABLE_RUNTIME_ACCESS,\r | |
57 | sizeof *PlatformConfig, PlatformConfig);\r | |
58 | return Status;\r | |
59 | }\r | |
60 | \r | |
61 | \r | |
62 | /**\r | |
63 | Load and deserialize platform configuration.\r | |
64 | \r | |
65 | When the function fails, output parameters are indeterminate.\r | |
66 | \r | |
67 | @param[out] PlatformConfig The platform configuration to receive the\r | |
68 | loaded data.\r | |
69 | \r | |
70 | @param[out] OptionalElements This bitmap describes the presence of optional\r | |
71 | configuration elements that have been loaded.\r | |
72 | PLATFORM_CONFIG_F_DOWNGRADE means that some\r | |
73 | unknown elements, present in the wire format,\r | |
74 | have been ignored.\r | |
75 | \r | |
76 | @retval EFI_SUCCESS Loading & deserialization successful.\r | |
77 | @return Error codes returned by GetVariable2().\r | |
78 | **/\r | |
79 | EFI_STATUS\r | |
80 | EFIAPI\r | |
81 | PlatformConfigLoad (\r | |
82 | OUT PLATFORM_CONFIG *PlatformConfig,\r | |
83 | OUT UINT64 *OptionalElements\r | |
84 | )\r | |
85 | {\r | |
86 | VOID *Data;\r | |
87 | UINTN DataSize;\r | |
88 | EFI_STATUS Status;\r | |
89 | \r | |
90 | //\r | |
91 | // Any translation done in PlatformConfigSave() would have to be mirrored\r | |
92 | // here. For now, just load the binary dump.\r | |
93 | //\r | |
94 | // Versioning of the binary wire format is implemented based on size\r | |
95 | // (only incremental changes, ie. new fields), and on GUID.\r | |
96 | // (Incompatible changes require a GUID change.)\r | |
97 | //\r | |
98 | Status = GetVariable2 (mVariableName, &gOvmfPlatformConfigGuid, &Data,\r | |
99 | &DataSize);\r | |
100 | if (EFI_ERROR (Status)) {\r | |
101 | return Status;\r | |
102 | }\r | |
103 | \r | |
104 | *OptionalElements = 0;\r | |
105 | if (DataSize > sizeof *PlatformConfig) {\r | |
106 | //\r | |
107 | // Handle firmware downgrade -- keep only leading part.\r | |
108 | //\r | |
109 | CopyMem (PlatformConfig, Data, sizeof *PlatformConfig);\r | |
110 | *OptionalElements |= PLATFORM_CONFIG_F_DOWNGRADE;\r | |
111 | } else {\r | |
112 | CopyMem (PlatformConfig, Data, DataSize);\r | |
113 | \r | |
114 | //\r | |
115 | // Handle firmware upgrade -- zero out missing fields.\r | |
116 | //\r | |
117 | ZeroMem ((UINT8 *)PlatformConfig + DataSize,\r | |
118 | sizeof *PlatformConfig - DataSize);\r | |
119 | }\r | |
120 | \r | |
121 | //\r | |
122 | // Based on DataSize, report the optional features that we recognize.\r | |
123 | //\r | |
124 | if (DataSize >= (OFFSET_OF (PLATFORM_CONFIG, VerticalResolution) +\r | |
125 | sizeof PlatformConfig->VerticalResolution)) {\r | |
126 | *OptionalElements |= PLATFORM_CONFIG_F_GRAPHICS_RESOLUTION;\r | |
127 | }\r | |
128 | \r | |
129 | FreePool (Data);\r | |
130 | return EFI_SUCCESS;\r | |
131 | }\r |