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1/** @file\r
2\r
3 AMD Sev Dxe driver. This driver is dispatched early in DXE, due to being list\r
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4 in APRIORI. It clears C-bit from MMIO and NonExistent Memory space when SEV\r
5 is enabled.\r
24e4ad75 6\r
84cddd70 7 Copyright (c) 2017 - 2020, AMD Inc. All rights reserved.<BR>\r
24e4ad75 8\r
b26f0cf9 9 SPDX-License-Identifier: BSD-2-Clause-Patent\r
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10\r
11**/\r
12\r
84cddd70 13#include <IndustryStandard/Q35MchIch9.h>\r
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14#include <Library/BaseLib.h>\r
15#include <Library/BaseMemoryLib.h>\r
c6073a0e 16#include <Library/DebugLib.h>\r
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17#include <Library/DxeServicesTableLib.h>\r
18#include <Library/MemEncryptSevLib.h>\r
c6073a0e 19#include <Library/MemoryAllocationLib.h>\r
5e2e5647 20#include <Library/PcdLib.h>\r
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21\r
22EFI_STATUS\r
23EFIAPI\r
24AmdSevDxeEntryPoint (\r
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25 IN EFI_HANDLE ImageHandle,\r
26 IN EFI_SYSTEM_TABLE *SystemTable\r
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27 )\r
28{\r
29 EFI_STATUS Status;\r
30 EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap;\r
31 UINTN NumEntries;\r
32 UINTN Index;\r
33\r
34 //\r
35 // Do nothing when SEV is not enabled\r
36 //\r
37 if (!MemEncryptSevIsEnabled ()) {\r
38 return EFI_UNSUPPORTED;\r
39 }\r
40\r
41 //\r
42 // Iterate through the GCD map and clear the C-bit from MMIO and NonExistent\r
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43 // memory space. The NonExistent memory space will be used for mapping the\r
44 // MMIO space added later (eg PciRootBridge). By clearing both known MMIO and\r
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45 // NonExistent memory space can gurantee that current and furture MMIO adds\r
46 // will have C-bit cleared.\r
47 //\r
48 Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);\r
49 if (!EFI_ERROR (Status)) {\r
50 for (Index = 0; Index < NumEntries; Index++) {\r
ac0a286f 51 CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc;\r
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52\r
53 Desc = &AllDescMap[Index];\r
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54 if ((Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo) ||\r
55 (Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent))\r
56 {\r
c394fa4c 57 Status = MemEncryptSevClearMmioPageEncMask (\r
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58 0,\r
59 Desc->BaseAddress,\r
c394fa4c 60 EFI_SIZE_TO_PAGES (Desc->Length)\r
c16d4e35 61 );\r
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62 ASSERT_EFI_ERROR (Status);\r
63 }\r
64 }\r
65\r
66 FreePool (AllDescMap);\r
67 }\r
68\r
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69 //\r
70 // If PCI Express is enabled, the MMCONFIG area has been reserved, rather\r
71 // than marked as MMIO, and so the C-bit won't be cleared by the above walk\r
72 // through the GCD map. Check for the MMCONFIG area and clear the C-bit for\r
73 // the range.\r
74 //\r
75 if (PcdGet16 (PcdOvmfHostBridgePciDevId) == INTEL_Q35_MCH_DEVICE_ID) {\r
c394fa4c 76 Status = MemEncryptSevClearMmioPageEncMask (\r
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77 0,\r
78 FixedPcdGet64 (PcdPciExpressBaseAddress),\r
c394fa4c 79 EFI_SIZE_TO_PAGES (SIZE_256MB)\r
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80 );\r
81\r
82 ASSERT_EFI_ERROR (Status);\r
83 }\r
84\r
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85 //\r
86 // When SMM is enabled, clear the C-bit from SMM Saved State Area\r
87 //\r
88 // NOTES: The SavedStateArea address cleared here is before SMBASE\r
89 // relocation. Currently, we do not clear the SavedStateArea address after\r
90 // SMBASE is relocated due to the following reasons:\r
91 //\r
92 // 1) Guest BIOS never access the relocated SavedStateArea.\r
93 //\r
94 // 2) The C-bit works on page-aligned address, but the SavedStateArea\r
95 // address is not a page-aligned. Theoretically, we could roundup the address\r
96 // and clear the C-bit of aligned address but looking carefully we found\r
97 // that some portion of the page contains code -- which will causes a bigger\r
98 // issues for SEV guest. When SEV is enabled, all the code must be encrypted\r
99 // otherwise hardware will cause trap.\r
100 //\r
101 // We restore the C-bit for this SMM Saved State Area after SMBASE relocation\r
102 // is completed (See OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c).\r
103 //\r
104 if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
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105 UINTN MapPagesBase;\r
106 UINTN MapPagesCount;\r
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107\r
108 Status = MemEncryptSevLocateInitialSmramSaveStateMapPages (\r
109 &MapPagesBase,\r
110 &MapPagesCount\r
111 );\r
112 ASSERT_EFI_ERROR (Status);\r
113\r
114 //\r
115 // Although these pages were set aside (i.e., allocated) by PlatformPei, we\r
116 // could be after a warm reboot from the OS. Don't leak any stale OS data\r
117 // to the hypervisor.\r
118 //\r
119 ZeroMem ((VOID *)MapPagesBase, EFI_PAGES_TO_SIZE (MapPagesCount));\r
120\r
121 Status = MemEncryptSevClearPageEncMask (\r
122 0, // Cr3BaseAddress -- use current CR3\r
123 MapPagesBase, // BaseAddress\r
adfa3327 124 MapPagesCount // NumPages\r
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125 );\r
126 if (EFI_ERROR (Status)) {\r
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127 DEBUG ((\r
128 DEBUG_ERROR,\r
129 "%a: MemEncryptSevClearPageEncMask(): %r\n",\r
130 __FUNCTION__,\r
131 Status\r
132 ));\r
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133 ASSERT (FALSE);\r
134 CpuDeadLoop ();\r
135 }\r
136 }\r
137\r
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138 return EFI_SUCCESS;\r
139}\r