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1 | /** @file\r |
2 | \r | |
3 | SEV-SNP Page Validation functions.\r | |
4 | \r | |
5 | Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>\r | |
6 | \r | |
7 | SPDX-License-Identifier: BSD-2-Clause-Patent\r | |
8 | \r | |
9 | **/\r | |
10 | \r | |
11 | #include <Uefi/UefiBaseType.h>\r | |
12 | #include <Library/BaseLib.h>\r | |
13 | #include <Library/BaseMemoryLib.h>\r | |
14 | #include <Library/MemEncryptSevLib.h>\r | |
15 | #include <Library/DebugLib.h>\r | |
16 | #include <Library/VmgExitLib.h>\r | |
17 | \r | |
18 | #include <Register/Amd/Ghcb.h>\r | |
19 | #include <Register/Amd/Msr.h>\r | |
20 | \r | |
21 | #include "SnpPageStateChange.h"\r | |
22 | \r | |
23 | #define IS_ALIGNED(x, y) ((((x) & (y - 1)) == 0))\r | |
24 | #define PAGES_PER_LARGE_ENTRY 512\r | |
25 | \r | |
26 | STATIC\r | |
27 | UINTN\r | |
28 | MemoryStateToGhcbOp (\r | |
29 | IN SEV_SNP_PAGE_STATE State\r | |
30 | )\r | |
31 | {\r | |
32 | UINTN Cmd;\r | |
33 | \r | |
34 | switch (State) {\r | |
35 | case SevSnpPageShared: Cmd = SNP_PAGE_STATE_SHARED;\r | |
36 | break;\r | |
37 | case SevSnpPagePrivate: Cmd = SNP_PAGE_STATE_PRIVATE;\r | |
38 | break;\r | |
39 | default: ASSERT (0);\r | |
40 | }\r | |
41 | \r | |
42 | return Cmd;\r | |
43 | }\r | |
44 | \r | |
45 | STATIC\r | |
46 | VOID\r | |
47 | SnpPageStateFailureTerminate (\r | |
48 | VOID\r | |
49 | )\r | |
50 | {\r | |
51 | MSR_SEV_ES_GHCB_REGISTER Msr;\r | |
52 | \r | |
53 | //\r | |
54 | // Use the GHCB MSR Protocol to request termination by the hypervisor\r | |
55 | //\r | |
56 | Msr.GhcbPhysicalAddress = 0;\r | |
57 | Msr.GhcbTerminate.Function = GHCB_INFO_TERMINATE_REQUEST;\r | |
58 | Msr.GhcbTerminate.ReasonCodeSet = GHCB_TERMINATE_GHCB;\r | |
59 | Msr.GhcbTerminate.ReasonCode = GHCB_TERMINATE_GHCB_GENERAL;\r | |
60 | AsmWriteMsr64 (MSR_SEV_ES_GHCB, Msr.GhcbPhysicalAddress);\r | |
61 | \r | |
62 | AsmVmgExit ();\r | |
63 | \r | |
64 | ASSERT (FALSE);\r | |
65 | CpuDeadLoop ();\r | |
66 | }\r | |
67 | \r | |
68 | /**\r | |
69 | This function issues the PVALIDATE instruction to validate or invalidate the memory\r | |
70 | range specified. If PVALIDATE returns size mismatch then it retry validating with\r | |
71 | smaller page size.\r | |
72 | \r | |
73 | */\r | |
74 | STATIC\r | |
75 | VOID\r | |
76 | PvalidateRange (\r | |
77 | IN SNP_PAGE_STATE_CHANGE_INFO *Info,\r | |
78 | IN UINTN StartIndex,\r | |
79 | IN UINTN EndIndex,\r | |
80 | IN BOOLEAN Validate\r | |
81 | )\r | |
82 | {\r | |
83 | UINTN Address, RmpPageSize, Ret, i;\r | |
84 | \r | |
85 | for ( ; StartIndex <= EndIndex; StartIndex++) {\r | |
86 | //\r | |
87 | // Get the address and the page size from the Info.\r | |
88 | //\r | |
89 | Address = Info->Entry[StartIndex].GuestFrameNumber << EFI_PAGE_SHIFT;\r | |
90 | RmpPageSize = Info->Entry[StartIndex].PageSize;\r | |
91 | \r | |
92 | Ret = AsmPvalidate (RmpPageSize, Validate, Address);\r | |
93 | \r | |
94 | //\r | |
95 | // If we fail to validate due to size mismatch then try with the\r | |
96 | // smaller page size. This senario will occur if the backing page in\r | |
97 | // the RMP entry is 4K and we are validating it as a 2MB.\r | |
98 | //\r | |
99 | if ((Ret == PVALIDATE_RET_SIZE_MISMATCH) && (RmpPageSize == PvalidatePageSize2MB)) {\r | |
100 | for (i = 0; i < PAGES_PER_LARGE_ENTRY; i++) {\r | |
101 | Ret = AsmPvalidate (PvalidatePageSize4K, Validate, Address);\r | |
102 | if (Ret) {\r | |
103 | break;\r | |
104 | }\r | |
105 | \r | |
106 | Address = Address + EFI_PAGE_SIZE;\r | |
107 | }\r | |
108 | }\r | |
109 | \r | |
110 | //\r | |
111 | // If validation failed then do not continue.\r | |
112 | //\r | |
113 | if (Ret) {\r | |
114 | DEBUG ((\r | |
115 | DEBUG_ERROR,\r | |
116 | "%a:%a: Failed to %a address 0x%Lx Error code %d\n",\r | |
117 | gEfiCallerBaseName,\r | |
118 | __FUNCTION__,\r | |
119 | Validate ? "Validate" : "Invalidate",\r | |
120 | Address,\r | |
121 | Ret\r | |
122 | ));\r | |
123 | SnpPageStateFailureTerminate ();\r | |
124 | }\r | |
125 | }\r | |
126 | }\r | |
127 | \r | |
128 | STATIC\r | |
129 | EFI_PHYSICAL_ADDRESS\r | |
130 | BuildPageStateBuffer (\r | |
131 | IN EFI_PHYSICAL_ADDRESS BaseAddress,\r | |
132 | IN EFI_PHYSICAL_ADDRESS EndAddress,\r | |
133 | IN SEV_SNP_PAGE_STATE State,\r | |
134 | IN BOOLEAN UseLargeEntry,\r | |
135 | IN SNP_PAGE_STATE_CHANGE_INFO *Info\r | |
136 | )\r | |
137 | {\r | |
138 | EFI_PHYSICAL_ADDRESS NextAddress;\r | |
139 | UINTN i, RmpPageSize;\r | |
140 | \r | |
141 | // Clear the page state structure\r | |
142 | SetMem (Info, sizeof (*Info), 0);\r | |
143 | \r | |
144 | i = 0;\r | |
145 | NextAddress = EndAddress;\r | |
146 | \r | |
147 | //\r | |
148 | // Populate the page state entry structure\r | |
149 | //\r | |
150 | while ((BaseAddress < EndAddress) && (i < SNP_PAGE_STATE_MAX_ENTRY)) {\r | |
151 | //\r | |
152 | // Is this a 2MB aligned page? Check if we can use the Large RMP entry.\r | |
153 | //\r | |
154 | if (UseLargeEntry && IS_ALIGNED (BaseAddress, SIZE_2MB) &&\r | |
155 | ((EndAddress - BaseAddress) >= SIZE_2MB))\r | |
156 | {\r | |
157 | RmpPageSize = PvalidatePageSize2MB;\r | |
158 | NextAddress = BaseAddress + SIZE_2MB;\r | |
159 | } else {\r | |
160 | RmpPageSize = PvalidatePageSize4K;\r | |
161 | NextAddress = BaseAddress + EFI_PAGE_SIZE;\r | |
162 | }\r | |
163 | \r | |
164 | Info->Entry[i].GuestFrameNumber = BaseAddress >> EFI_PAGE_SHIFT;\r | |
165 | Info->Entry[i].PageSize = RmpPageSize;\r | |
166 | Info->Entry[i].Operation = MemoryStateToGhcbOp (State);\r | |
167 | Info->Entry[i].CurrentPage = 0;\r | |
168 | Info->Header.EndEntry = (UINT16)i;\r | |
169 | \r | |
170 | BaseAddress = NextAddress;\r | |
171 | i++;\r | |
172 | }\r | |
173 | \r | |
174 | return NextAddress;\r | |
175 | }\r | |
176 | \r | |
177 | STATIC\r | |
178 | VOID\r | |
179 | PageStateChangeVmgExit (\r | |
180 | IN GHCB *Ghcb,\r | |
181 | IN SNP_PAGE_STATE_CHANGE_INFO *Info\r | |
182 | )\r | |
183 | {\r | |
184 | EFI_STATUS Status;\r | |
185 | \r | |
186 | //\r | |
187 | // As per the GHCB specification, the hypervisor can resume the guest before\r | |
188 | // processing all the entries. Checks whether all the entries are processed.\r | |
189 | //\r | |
190 | // The stragtegy here is to wait for the hypervisor to change the page\r | |
191 | // state in the RMP table before guest access the memory pages. If the\r | |
192 | // page state was not successful, then later memory access will result\r | |
193 | // in the crash.\r | |
194 | //\r | |
195 | while (Info->Header.CurrentEntry <= Info->Header.EndEntry) {\r | |
196 | Ghcb->SaveArea.SwScratch = (UINT64)Ghcb->SharedBuffer;\r | |
197 | VmgSetOffsetValid (Ghcb, GhcbSwScratch);\r | |
198 | \r | |
199 | Status = VmgExit (Ghcb, SVM_EXIT_SNP_PAGE_STATE_CHANGE, 0, 0);\r | |
200 | \r | |
201 | //\r | |
202 | // The Page State Change VMGEXIT can pass the failure through the\r | |
203 | // ExitInfo2. Lets check both the return value as well as ExitInfo2.\r | |
204 | //\r | |
205 | if ((Status != 0) || (Ghcb->SaveArea.SwExitInfo2)) {\r | |
206 | SnpPageStateFailureTerminate ();\r | |
207 | }\r | |
208 | }\r | |
209 | }\r | |
210 | \r | |
211 | /**\r | |
212 | The function is used to set the page state when SEV-SNP is active. The page state\r | |
213 | transition consist of changing the page ownership in the RMP table, and using the\r | |
214 | PVALIDATE instruction to update the Validated bit in RMP table.\r | |
215 | \r | |
216 | When the UseLargeEntry is set to TRUE, then function will try to use the large RMP\r | |
217 | entry (whevever possible).\r | |
218 | */\r | |
219 | VOID\r | |
220 | InternalSetPageState (\r | |
221 | IN EFI_PHYSICAL_ADDRESS BaseAddress,\r | |
222 | IN UINTN NumPages,\r | |
223 | IN SEV_SNP_PAGE_STATE State,\r | |
224 | IN BOOLEAN UseLargeEntry\r | |
225 | )\r | |
226 | {\r | |
227 | GHCB *Ghcb;\r | |
228 | EFI_PHYSICAL_ADDRESS NextAddress, EndAddress;\r | |
229 | MSR_SEV_ES_GHCB_REGISTER Msr;\r | |
230 | BOOLEAN InterruptState;\r | |
231 | SNP_PAGE_STATE_CHANGE_INFO *Info;\r | |
232 | \r | |
233 | Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);\r | |
234 | Ghcb = Msr.Ghcb;\r | |
235 | \r | |
236 | EndAddress = BaseAddress + EFI_PAGES_TO_SIZE (NumPages);\r | |
237 | \r | |
238 | DEBUG ((\r | |
239 | DEBUG_VERBOSE,\r | |
240 | "%a:%a Address 0x%Lx - 0x%Lx State = %a LargeEntry = %d\n",\r | |
241 | gEfiCallerBaseName,\r | |
242 | __FUNCTION__,\r | |
243 | BaseAddress,\r | |
244 | EndAddress,\r | |
245 | State == SevSnpPageShared ? "Shared" : "Private",\r | |
246 | UseLargeEntry\r | |
247 | ));\r | |
248 | \r | |
249 | while (BaseAddress < EndAddress) {\r | |
250 | UINTN CurrentEntry, EndEntry;\r | |
251 | \r | |
252 | //\r | |
253 | // Initialize the GHCB\r | |
254 | //\r | |
255 | VmgInit (Ghcb, &InterruptState);\r | |
256 | \r | |
257 | //\r | |
258 | // Build the page state structure\r | |
259 | //\r | |
260 | Info = (SNP_PAGE_STATE_CHANGE_INFO *)Ghcb->SharedBuffer;\r | |
261 | NextAddress = BuildPageStateBuffer (\r | |
262 | BaseAddress,\r | |
263 | EndAddress,\r | |
264 | State,\r | |
265 | UseLargeEntry,\r | |
266 | Info\r | |
267 | );\r | |
268 | \r | |
269 | //\r | |
270 | // Save the current and end entry from the page state structure. We need\r | |
271 | // it later.\r | |
272 | //\r | |
273 | CurrentEntry = Info->Header.CurrentEntry;\r | |
274 | EndEntry = Info->Header.EndEntry;\r | |
275 | \r | |
276 | //\r | |
277 | // If the caller requested to change the page state to shared then\r | |
278 | // invalidate the pages before making the page shared in the RMP table.\r | |
279 | //\r | |
280 | if (State == SevSnpPageShared) {\r | |
281 | PvalidateRange (Info, CurrentEntry, EndEntry, FALSE);\r | |
282 | }\r | |
283 | \r | |
284 | //\r | |
285 | // Invoke the page state change VMGEXIT.\r | |
286 | //\r | |
287 | PageStateChangeVmgExit (Ghcb, Info);\r | |
288 | \r | |
289 | //\r | |
290 | // If the caller requested to change the page state to private then\r | |
291 | // validate the pages after it has been added in the RMP table.\r | |
292 | //\r | |
293 | if (State == SevSnpPagePrivate) {\r | |
294 | PvalidateRange (Info, CurrentEntry, EndEntry, TRUE);\r | |
295 | }\r | |
296 | \r | |
297 | VmgDone (Ghcb, InterruptState);\r | |
298 | \r | |
299 | BaseAddress = NextAddress;\r | |
300 | }\r | |
301 | }\r |