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1 /** @file
2 The CPU specific programming for PiSmmCpuDxeSmm module.
3
4 Copyright (c) 2010 - 2019, Intel Corporation. All rights reserved.<BR>
5 SPDX-License-Identifier: BSD-2-Clause-Patent
6
7 **/
8
9 #include <PiSmm.h>
10 #include <Library/SmmCpuFeaturesLib.h>
11 #include <Library/BaseLib.h>
12 #include <Library/MtrrLib.h>
13 #include <Library/PcdLib.h>
14 #include <Library/MemoryAllocationLib.h>
15 #include <Library/DebugLib.h>
16 #include <Register/Intel/Cpuid.h>
17 #include <Register/Intel/SmramSaveStateMap.h>
18
19 //
20 // Machine Specific Registers (MSRs)
21 //
22 #define SMM_FEATURES_LIB_IA32_MTRR_CAP 0x0FE
23 #define SMM_FEATURES_LIB_IA32_FEATURE_CONTROL 0x03A
24 #define SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE 0x1F2
25 #define SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK 0x1F3
26 #define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE 0x0A0
27 #define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK 0x0A1
28 #define EFI_MSR_SMRR_MASK 0xFFFFF000
29 #define EFI_MSR_SMRR_PHYS_MASK_VALID BIT11
30 #define SMM_FEATURES_LIB_SMM_FEATURE_CONTROL 0x4E0
31
32 //
33 // MSRs required for configuration of SMM Code Access Check
34 //
35 #define SMM_FEATURES_LIB_IA32_MCA_CAP 0x17D
36 #define SMM_CODE_ACCESS_CHK_BIT BIT58
37
38 /**
39 Internal worker function that is called to complete CPU initialization at the
40 end of SmmCpuFeaturesInitializeProcessor().
41
42 **/
43 VOID
44 FinishSmmCpuFeaturesInitializeProcessor (
45 VOID
46 );
47
48 //
49 // Set default value to assume SMRR is not supported
50 //
51 BOOLEAN mSmrrSupported = FALSE;
52
53 //
54 // Set default value to assume MSR_SMM_FEATURE_CONTROL is not supported
55 //
56 BOOLEAN mSmmFeatureControlSupported = FALSE;
57
58 //
59 // Set default value to assume IA-32 Architectural MSRs are used
60 //
61 UINT32 mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE;
62 UINT32 mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK;
63
64 //
65 // Set default value to assume MTRRs need to be configured on each SMI
66 //
67 BOOLEAN mNeedConfigureMtrrs = TRUE;
68
69 //
70 // Array for state of SMRR enable on all CPUs
71 //
72 BOOLEAN *mSmrrEnabled;
73
74 /**
75 The constructor function
76
77 @param[in] ImageHandle The firmware allocated handle for the EFI image.
78 @param[in] SystemTable A pointer to the EFI System Table.
79
80 @retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
81
82 **/
83 EFI_STATUS
84 EFIAPI
85 SmmCpuFeaturesLibConstructor (
86 IN EFI_HANDLE ImageHandle,
87 IN EFI_SYSTEM_TABLE *SystemTable
88 )
89 {
90 UINT32 RegEax;
91 UINT32 RegEdx;
92 UINTN FamilyId;
93 UINTN ModelId;
94
95 //
96 // Retrieve CPU Family and Model
97 //
98 AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
99 FamilyId = (RegEax >> 8) & 0xf;
100 ModelId = (RegEax >> 4) & 0xf;
101 if (FamilyId == 0x06 || FamilyId == 0x0f) {
102 ModelId = ModelId | ((RegEax >> 12) & 0xf0);
103 }
104
105 //
106 // Check CPUID(CPUID_VERSION_INFO).EDX[12] for MTRR capability
107 //
108 if ((RegEdx & BIT12) != 0) {
109 //
110 // Check MTRR_CAP MSR bit 11 for SMRR support
111 //
112 if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MTRR_CAP) & BIT11) != 0) {
113 mSmrrSupported = TRUE;
114 }
115 }
116
117 //
118 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
119 // Volume 3C, Section 35.3 MSRs in the Intel(R) Atom(TM) Processor Family
120 //
121 // If CPU Family/Model is 06_1CH, 06_26H, 06_27H, 06_35H or 06_36H, then
122 // SMRR Physical Base and SMM Physical Mask MSRs are not available.
123 //
124 if (FamilyId == 0x06) {
125 if (ModelId == 0x1C || ModelId == 0x26 || ModelId == 0x27 || ModelId == 0x35 || ModelId == 0x36) {
126 mSmrrSupported = FALSE;
127 }
128 }
129
130 //
131 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
132 // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
133 //
134 // If CPU Family/Model is 06_0F or 06_17, then use Intel(R) Core(TM) 2
135 // Processor Family MSRs
136 //
137 if (FamilyId == 0x06) {
138 if (ModelId == 0x17 || ModelId == 0x0f) {
139 mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE;
140 mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK;
141 }
142 }
143
144 //
145 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
146 // Volume 3C, Section 34.4.2 SMRAM Caching
147 // An IA-32 processor does not automatically write back and invalidate its
148 // caches before entering SMM or before exiting SMM. Because of this behavior,
149 // care must be taken in the placement of the SMRAM in system memory and in
150 // the caching of the SMRAM to prevent cache incoherence when switching back
151 // and forth between SMM and protected mode operation.
152 //
153 // An IA-32 processor is a processor that does not support the Intel 64
154 // Architecture. Support for the Intel 64 Architecture can be detected from
155 // CPUID(CPUID_EXTENDED_CPU_SIG).EDX[29]
156 //
157 // If an IA-32 processor is detected, then set mNeedConfigureMtrrs to TRUE,
158 // so caches are flushed on SMI entry and SMI exit, the interrupted code
159 // MTRRs are saved/restored, and MTRRs for SMM are loaded.
160 //
161 AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
162 if (RegEax >= CPUID_EXTENDED_CPU_SIG) {
163 AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &RegEdx);
164 if ((RegEdx & BIT29) != 0) {
165 mNeedConfigureMtrrs = FALSE;
166 }
167 }
168
169 //
170 // Allocate array for state of SMRR enable on all CPUs
171 //
172 mSmrrEnabled = (BOOLEAN *)AllocatePool (sizeof (BOOLEAN) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
173 ASSERT (mSmrrEnabled != NULL);
174
175 return EFI_SUCCESS;
176 }
177
178 /**
179 Called during the very first SMI into System Management Mode to initialize
180 CPU features, including SMBASE, for the currently executing CPU. Since this
181 is the first SMI, the SMRAM Save State Map is at the default address of
182 SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET. The currently executing
183 CPU is specified by CpuIndex and CpuIndex can be used to access information
184 about the currently executing CPU in the ProcessorInfo array and the
185 HotPlugCpuData data structure.
186
187 @param[in] CpuIndex The index of the CPU to initialize. The value
188 must be between 0 and the NumberOfCpus field in
189 the System Management System Table (SMST).
190 @param[in] IsMonarch TRUE if the CpuIndex is the index of the CPU that
191 was elected as monarch during System Management
192 Mode initialization.
193 FALSE if the CpuIndex is not the index of the CPU
194 that was elected as monarch during System
195 Management Mode initialization.
196 @param[in] ProcessorInfo Pointer to an array of EFI_PROCESSOR_INFORMATION
197 structures. ProcessorInfo[CpuIndex] contains the
198 information for the currently executing CPU.
199 @param[in] CpuHotPlugData Pointer to the CPU_HOT_PLUG_DATA structure that
200 contains the ApidId and SmBase arrays.
201 **/
202 VOID
203 EFIAPI
204 SmmCpuFeaturesInitializeProcessor (
205 IN UINTN CpuIndex,
206 IN BOOLEAN IsMonarch,
207 IN EFI_PROCESSOR_INFORMATION *ProcessorInfo,
208 IN CPU_HOT_PLUG_DATA *CpuHotPlugData
209 )
210 {
211 SMRAM_SAVE_STATE_MAP *CpuState;
212 UINT64 FeatureControl;
213 UINT32 RegEax;
214 UINT32 RegEdx;
215 UINTN FamilyId;
216 UINTN ModelId;
217
218 //
219 // Configure SMBASE.
220 //
221 CpuState = (SMRAM_SAVE_STATE_MAP *)(UINTN)(SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET);
222 CpuState->x86.SMBASE = (UINT32)CpuHotPlugData->SmBase[CpuIndex];
223
224 //
225 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
226 // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
227 //
228 // If Intel(R) Core(TM) Core(TM) 2 Processor Family MSRs are being used, then
229 // make sure SMRR Enable(BIT3) of MSR_FEATURE_CONTROL MSR(0x3A) is set before
230 // accessing SMRR base/mask MSRs. If Lock(BIT0) of MSR_FEATURE_CONTROL MSR(0x3A)
231 // is set, then the MSR is locked and can not be modified.
232 //
233 if (mSmrrSupported && mSmrrPhysBaseMsr == SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE) {
234 FeatureControl = AsmReadMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL);
235 if ((FeatureControl & BIT3) == 0) {
236 if ((FeatureControl & BIT0) == 0) {
237 AsmWriteMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL, FeatureControl | BIT3);
238 } else {
239 mSmrrSupported = FALSE;
240 }
241 }
242 }
243
244 //
245 // If SMRR is supported, then program SMRR base/mask MSRs.
246 // The EFI_MSR_SMRR_PHYS_MASK_VALID bit is not set until the first normal SMI.
247 // The code that initializes SMM environment is running in normal mode
248 // from SMRAM region. If SMRR is enabled here, then the SMRAM region
249 // is protected and the normal mode code execution will fail.
250 //
251 if (mSmrrSupported) {
252 //
253 // SMRR size cannot be less than 4-KBytes
254 // SMRR size must be of length 2^n
255 // SMRR base alignment cannot be less than SMRR length
256 //
257 if ((CpuHotPlugData->SmrrSize < SIZE_4KB) ||
258 (CpuHotPlugData->SmrrSize != GetPowerOfTwo32 (CpuHotPlugData->SmrrSize)) ||
259 ((CpuHotPlugData->SmrrBase & ~(CpuHotPlugData->SmrrSize - 1)) != CpuHotPlugData->SmrrBase)) {
260 //
261 // Print message and halt if CPU is Monarch
262 //
263 if (IsMonarch) {
264 DEBUG ((DEBUG_ERROR, "SMM Base/Size does not meet alignment/size requirement!\n"));
265 CpuDeadLoop ();
266 }
267 } else {
268 AsmWriteMsr64 (mSmrrPhysBaseMsr, CpuHotPlugData->SmrrBase | MTRR_CACHE_WRITE_BACK);
269 AsmWriteMsr64 (mSmrrPhysMaskMsr, (~(CpuHotPlugData->SmrrSize - 1) & EFI_MSR_SMRR_MASK));
270 mSmrrEnabled[CpuIndex] = FALSE;
271 }
272 }
273
274 //
275 // Retrieve CPU Family and Model
276 //
277 AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
278 FamilyId = (RegEax >> 8) & 0xf;
279 ModelId = (RegEax >> 4) & 0xf;
280 if (FamilyId == 0x06 || FamilyId == 0x0f) {
281 ModelId = ModelId | ((RegEax >> 12) & 0xf0);
282 }
283
284 //
285 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
286 // Volume 3C, Section 35.10.1 MSRs in 4th Generation Intel(R) Core(TM)
287 // Processor Family.
288 //
289 // If CPU Family/Model is 06_3C, 06_45, or 06_46 then use 4th Generation
290 // Intel(R) Core(TM) Processor Family MSRs.
291 //
292 if (FamilyId == 0x06) {
293 if (ModelId == 0x3C || ModelId == 0x45 || ModelId == 0x46 ||
294 ModelId == 0x3D || ModelId == 0x47 || ModelId == 0x4E || ModelId == 0x4F ||
295 ModelId == 0x3F || ModelId == 0x56 || ModelId == 0x57 || ModelId == 0x5C) {
296 //
297 // Check to see if the CPU supports the SMM Code Access Check feature
298 // Do not access this MSR unless the CPU supports the SmmRegFeatureControl
299 //
300 if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MCA_CAP) & SMM_CODE_ACCESS_CHK_BIT) != 0) {
301 mSmmFeatureControlSupported = TRUE;
302 }
303 }
304 }
305
306 //
307 // Call internal worker function that completes the CPU initialization
308 //
309 FinishSmmCpuFeaturesInitializeProcessor ();
310 }
311
312 /**
313 This function updates the SMRAM save state on the currently executing CPU
314 to resume execution at a specific address after an RSM instruction. This
315 function must evaluate the SMRAM save state to determine the execution mode
316 the RSM instruction resumes and update the resume execution address with
317 either NewInstructionPointer32 or NewInstructionPoint. The auto HALT restart
318 flag in the SMRAM save state must always be cleared. This function returns
319 the value of the instruction pointer from the SMRAM save state that was
320 replaced. If this function returns 0, then the SMRAM save state was not
321 modified.
322
323 This function is called during the very first SMI on each CPU after
324 SmmCpuFeaturesInitializeProcessor() to set a flag in normal execution mode
325 to signal that the SMBASE of each CPU has been updated before the default
326 SMBASE address is used for the first SMI to the next CPU.
327
328 @param[in] CpuIndex The index of the CPU to hook. The value
329 must be between 0 and the NumberOfCpus
330 field in the System Management System Table
331 (SMST).
332 @param[in] CpuState Pointer to SMRAM Save State Map for the
333 currently executing CPU.
334 @param[in] NewInstructionPointer32 Instruction pointer to use if resuming to
335 32-bit execution mode from 64-bit SMM.
336 @param[in] NewInstructionPointer Instruction pointer to use if resuming to
337 same execution mode as SMM.
338
339 @retval 0 This function did modify the SMRAM save state.
340 @retval > 0 The original instruction pointer value from the SMRAM save state
341 before it was replaced.
342 **/
343 UINT64
344 EFIAPI
345 SmmCpuFeaturesHookReturnFromSmm (
346 IN UINTN CpuIndex,
347 IN SMRAM_SAVE_STATE_MAP *CpuState,
348 IN UINT64 NewInstructionPointer32,
349 IN UINT64 NewInstructionPointer
350 )
351 {
352 return 0;
353 }
354
355 /**
356 Hook point in normal execution mode that allows the one CPU that was elected
357 as monarch during System Management Mode initialization to perform additional
358 initialization actions immediately after all of the CPUs have processed their
359 first SMI and called SmmCpuFeaturesInitializeProcessor() relocating SMBASE
360 into a buffer in SMRAM and called SmmCpuFeaturesHookReturnFromSmm().
361 **/
362 VOID
363 EFIAPI
364 SmmCpuFeaturesSmmRelocationComplete (
365 VOID
366 )
367 {
368 }
369
370 /**
371 Determines if MTRR registers must be configured to set SMRAM cache-ability
372 when executing in System Management Mode.
373
374 @retval TRUE MTRR registers must be configured to set SMRAM cache-ability.
375 @retval FALSE MTRR registers do not need to be configured to set SMRAM
376 cache-ability.
377 **/
378 BOOLEAN
379 EFIAPI
380 SmmCpuFeaturesNeedConfigureMtrrs (
381 VOID
382 )
383 {
384 return mNeedConfigureMtrrs;
385 }
386
387 /**
388 Disable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
389 returns TRUE.
390 **/
391 VOID
392 EFIAPI
393 SmmCpuFeaturesDisableSmrr (
394 VOID
395 )
396 {
397 if (mSmrrSupported && mNeedConfigureMtrrs) {
398 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) & ~EFI_MSR_SMRR_PHYS_MASK_VALID);
399 }
400 }
401
402 /**
403 Enable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
404 returns TRUE.
405 **/
406 VOID
407 EFIAPI
408 SmmCpuFeaturesReenableSmrr (
409 VOID
410 )
411 {
412 if (mSmrrSupported && mNeedConfigureMtrrs) {
413 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
414 }
415 }
416
417 /**
418 Processor specific hook point each time a CPU enters System Management Mode.
419
420 @param[in] CpuIndex The index of the CPU that has entered SMM. The value
421 must be between 0 and the NumberOfCpus field in the
422 System Management System Table (SMST).
423 **/
424 VOID
425 EFIAPI
426 SmmCpuFeaturesRendezvousEntry (
427 IN UINTN CpuIndex
428 )
429 {
430 //
431 // If SMRR is supported and this is the first normal SMI, then enable SMRR
432 //
433 if (mSmrrSupported && !mSmrrEnabled[CpuIndex]) {
434 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64 (mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
435 mSmrrEnabled[CpuIndex] = TRUE;
436 }
437 }
438
439 /**
440 Processor specific hook point each time a CPU exits System Management Mode.
441
442 @param[in] CpuIndex The index of the CPU that is exiting SMM. The value must
443 be between 0 and the NumberOfCpus field in the System
444 Management System Table (SMST).
445 **/
446 VOID
447 EFIAPI
448 SmmCpuFeaturesRendezvousExit (
449 IN UINTN CpuIndex
450 )
451 {
452 }
453
454 /**
455 Check to see if an SMM register is supported by a specified CPU.
456
457 @param[in] CpuIndex The index of the CPU to check for SMM register support.
458 The value must be between 0 and the NumberOfCpus field
459 in the System Management System Table (SMST).
460 @param[in] RegName Identifies the SMM register to check for support.
461
462 @retval TRUE The SMM register specified by RegName is supported by the CPU
463 specified by CpuIndex.
464 @retval FALSE The SMM register specified by RegName is not supported by the
465 CPU specified by CpuIndex.
466 **/
467 BOOLEAN
468 EFIAPI
469 SmmCpuFeaturesIsSmmRegisterSupported (
470 IN UINTN CpuIndex,
471 IN SMM_REG_NAME RegName
472 )
473 {
474 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
475 return TRUE;
476 }
477 return FALSE;
478 }
479
480 /**
481 Returns the current value of the SMM register for the specified CPU.
482 If the SMM register is not supported, then 0 is returned.
483
484 @param[in] CpuIndex The index of the CPU to read the SMM register. The
485 value must be between 0 and the NumberOfCpus field in
486 the System Management System Table (SMST).
487 @param[in] RegName Identifies the SMM register to read.
488
489 @return The value of the SMM register specified by RegName from the CPU
490 specified by CpuIndex.
491 **/
492 UINT64
493 EFIAPI
494 SmmCpuFeaturesGetSmmRegister (
495 IN UINTN CpuIndex,
496 IN SMM_REG_NAME RegName
497 )
498 {
499 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
500 return AsmReadMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL);
501 }
502 return 0;
503 }
504
505 /**
506 Sets the value of an SMM register on a specified CPU.
507 If the SMM register is not supported, then no action is performed.
508
509 @param[in] CpuIndex The index of the CPU to write the SMM register. The
510 value must be between 0 and the NumberOfCpus field in
511 the System Management System Table (SMST).
512 @param[in] RegName Identifies the SMM register to write.
513 registers are read-only.
514 @param[in] Value The value to write to the SMM register.
515 **/
516 VOID
517 EFIAPI
518 SmmCpuFeaturesSetSmmRegister (
519 IN UINTN CpuIndex,
520 IN SMM_REG_NAME RegName,
521 IN UINT64 Value
522 )
523 {
524 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
525 AsmWriteMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL, Value);
526 }
527 }
528
529 /**
530 Read an SMM Save State register on the target processor. If this function
531 returns EFI_UNSUPPORTED, then the caller is responsible for reading the
532 SMM Save Sate register.
533
534 @param[in] CpuIndex The index of the CPU to read the SMM Save State. The
535 value must be between 0 and the NumberOfCpus field in
536 the System Management System Table (SMST).
537 @param[in] Register The SMM Save State register to read.
538 @param[in] Width The number of bytes to read from the CPU save state.
539 @param[out] Buffer Upon return, this holds the CPU register value read
540 from the save state.
541
542 @retval EFI_SUCCESS The register was read from Save State.
543 @retval EFI_INVALID_PARAMTER Buffer is NULL.
544 @retval EFI_UNSUPPORTED This function does not support reading Register.
545
546 **/
547 EFI_STATUS
548 EFIAPI
549 SmmCpuFeaturesReadSaveStateRegister (
550 IN UINTN CpuIndex,
551 IN EFI_SMM_SAVE_STATE_REGISTER Register,
552 IN UINTN Width,
553 OUT VOID *Buffer
554 )
555 {
556 return EFI_UNSUPPORTED;
557 }
558
559 /**
560 Writes an SMM Save State register on the target processor. If this function
561 returns EFI_UNSUPPORTED, then the caller is responsible for writing the
562 SMM Save Sate register.
563
564 @param[in] CpuIndex The index of the CPU to write the SMM Save State. The
565 value must be between 0 and the NumberOfCpus field in
566 the System Management System Table (SMST).
567 @param[in] Register The SMM Save State register to write.
568 @param[in] Width The number of bytes to write to the CPU save state.
569 @param[in] Buffer Upon entry, this holds the new CPU register value.
570
571 @retval EFI_SUCCESS The register was written to Save State.
572 @retval EFI_INVALID_PARAMTER Buffer is NULL.
573 @retval EFI_UNSUPPORTED This function does not support writing Register.
574 **/
575 EFI_STATUS
576 EFIAPI
577 SmmCpuFeaturesWriteSaveStateRegister (
578 IN UINTN CpuIndex,
579 IN EFI_SMM_SAVE_STATE_REGISTER Register,
580 IN UINTN Width,
581 IN CONST VOID *Buffer
582 )
583 {
584 return EFI_UNSUPPORTED;
585 }
586
587 /**
588 This function is hook point called after the gEfiSmmReadyToLockProtocolGuid
589 notification is completely processed.
590 **/
591 VOID
592 EFIAPI
593 SmmCpuFeaturesCompleteSmmReadyToLock (
594 VOID
595 )
596 {
597 }
598
599 /**
600 This API provides a method for a CPU to allocate a specific region for storing page tables.
601
602 This API can be called more once to allocate memory for page tables.
603
604 Allocates the number of 4KB pages of type EfiRuntimeServicesData and returns a pointer to the
605 allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
606 is returned. If there is not enough memory remaining to satisfy the request, then NULL is
607 returned.
608
609 This function can also return NULL if there is no preference on where the page tables are allocated in SMRAM.
610
611 @param Pages The number of 4 KB pages to allocate.
612
613 @return A pointer to the allocated buffer for page tables.
614 @retval NULL Fail to allocate a specific region for storing page tables,
615 Or there is no preference on where the page tables are allocated in SMRAM.
616
617 **/
618 VOID *
619 EFIAPI
620 SmmCpuFeaturesAllocatePageTableMemory (
621 IN UINTN Pages
622 )
623 {
624 return NULL;
625 }
626