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1 | /** @file\r |
2 | X64 #VC Exception Handler functon.\r | |
3 | \r | |
4 | Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>\r | |
5 | SPDX-License-Identifier: BSD-2-Clause-Patent\r | |
6 | \r | |
7 | **/\r | |
8 | \r | |
9 | #include <Base.h>\r | |
10 | #include <Uefi.h>\r | |
11 | #include <Library/BaseMemoryLib.h>\r | |
12 | #include <Library/MemEncryptSevLib.h>\r | |
13 | #include <Library/VmgExitLib.h>\r | |
14 | #include <Register/Amd/Msr.h>\r | |
15 | \r | |
16 | #include "VmgExitVcHandler.h"\r | |
17 | \r | |
18 | /**\r | |
19 | Handle a #VC exception.\r | |
20 | \r | |
21 | Performs the necessary processing to handle a #VC exception.\r | |
22 | \r | |
23 | @param[in, out] ExceptionType Pointer to an EFI_EXCEPTION_TYPE to be set\r | |
24 | as value to use on error.\r | |
25 | @param[in, out] SystemContext Pointer to EFI_SYSTEM_CONTEXT\r | |
26 | \r | |
27 | @retval EFI_SUCCESS Exception handled\r | |
28 | @retval EFI_UNSUPPORTED #VC not supported, (new) exception value to\r | |
29 | propagate provided\r | |
30 | @retval EFI_PROTOCOL_ERROR #VC handling failed, (new) exception value to\r | |
31 | propagate provided\r | |
32 | \r | |
33 | **/\r | |
34 | EFI_STATUS\r | |
35 | EFIAPI\r | |
36 | VmgExitHandleVc (\r | |
37 | IN OUT EFI_EXCEPTION_TYPE *ExceptionType,\r | |
38 | IN OUT EFI_SYSTEM_CONTEXT SystemContext\r | |
39 | )\r | |
40 | {\r | |
41 | MSR_SEV_ES_GHCB_REGISTER Msr;\r | |
42 | GHCB *Ghcb;\r | |
43 | GHCB *GhcbBackup;\r | |
44 | EFI_STATUS VcRet;\r | |
45 | BOOLEAN InterruptState;\r | |
46 | SEV_ES_PER_CPU_DATA *SevEsData;\r | |
47 | \r | |
48 | InterruptState = GetInterruptState ();\r | |
49 | if (InterruptState) {\r | |
50 | DisableInterrupts ();\r | |
51 | }\r | |
52 | \r | |
53 | Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);\r | |
54 | ASSERT (Msr.GhcbInfo.Function == 0);\r | |
55 | ASSERT (Msr.Ghcb != 0);\r | |
56 | \r | |
ac0a286f | 57 | Ghcb = Msr.Ghcb;\r |
5667dc43 TL |
58 | GhcbBackup = NULL;\r |
59 | \r | |
ac0a286f | 60 | SevEsData = (SEV_ES_PER_CPU_DATA *)(Ghcb + 1);\r |
5667dc43 TL |
61 | SevEsData->VcCount++;\r |
62 | \r | |
63 | //\r | |
64 | // Check for maximum PEI/DXE #VC nesting.\r | |
65 | //\r | |
66 | if (SevEsData->VcCount > VMGEXIT_MAXIMUM_VC_COUNT) {\r | |
67 | VmgExitIssueAssert (SevEsData);\r | |
68 | } else if (SevEsData->VcCount > 1) {\r | |
69 | //\r | |
70 | // Nested #VC\r | |
71 | //\r | |
72 | if (SevEsData->GhcbBackupPages == NULL) {\r | |
73 | VmgExitIssueAssert (SevEsData);\r | |
74 | }\r | |
75 | \r | |
76 | //\r | |
77 | // Save the active GHCB to a backup page.\r | |
78 | // To access the correct backup page, increment the backup page pointer\r | |
79 | // based on the current VcCount.\r | |
80 | //\r | |
ac0a286f | 81 | GhcbBackup = (GHCB *)SevEsData->GhcbBackupPages;\r |
5667dc43 TL |
82 | GhcbBackup += (SevEsData->VcCount - 2);\r |
83 | \r | |
84 | CopyMem (GhcbBackup, Ghcb, sizeof (*Ghcb));\r | |
85 | }\r | |
86 | \r | |
87 | VcRet = InternalVmgExitHandleVc (Ghcb, ExceptionType, SystemContext);\r | |
88 | \r | |
89 | if (GhcbBackup != NULL) {\r | |
90 | //\r | |
91 | // Restore the active GHCB from the backup page.\r | |
92 | //\r | |
93 | CopyMem (Ghcb, GhcbBackup, sizeof (*Ghcb));\r | |
94 | }\r | |
95 | \r | |
96 | SevEsData->VcCount--;\r | |
97 | \r | |
98 | if (InterruptState) {\r | |
99 | EnableInterrupts ();\r | |
100 | }\r | |
101 | \r | |
102 | return VcRet;\r | |
103 | }\r |