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1 /** @file
2 The CPU specific programming for PiSmmCpuDxeSmm module.
3
4 Copyright (c) 2010 - 2015, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 **/
14
15 #include <PiSmm.h>
16 #include <Library/SmmCpuFeaturesLib.h>
17 #include <Library/BaseLib.h>
18 #include <Library/MtrrLib.h>
19 #include <Library/PcdLib.h>
20 #include <Library/MemoryAllocationLib.h>
21 #include <Library/DebugLib.h>
22 #include <Register/Cpuid.h>
23 #include <Register/SmramSaveStateMap.h>
24
25 //
26 // Machine Specific Registers (MSRs)
27 //
28 #define SMM_FEATURES_LIB_IA32_MTRR_CAP 0x0FE
29 #define SMM_FEATURES_LIB_IA32_FEATURE_CONTROL 0x03A
30 #define SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE 0x1F2
31 #define SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK 0x1F3
32 #define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE 0x0A0
33 #define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK 0x0A1
34 #define EFI_MSR_SMRR_MASK 0xFFFFF000
35 #define EFI_MSR_SMRR_PHYS_MASK_VALID BIT11
36 #define SMM_FEATURES_LIB_SMM_FEATURE_CONTROL 0x4E0
37
38 //
39 // MSRs required for configuration of SMM Code Access Check
40 //
41 #define SMM_FEATURES_LIB_IA32_MCA_CAP 0x17D
42 #define SMM_CODE_ACCESS_CHK_BIT BIT58
43
44 //
45 // Set default value to assume SMRR is not supported
46 //
47 BOOLEAN mSmrrSupported = FALSE;
48
49 //
50 // Set default value to assume MSR_SMM_FEATURE_CONTROL is not supported
51 //
52 BOOLEAN mSmmFeatureControlSupported = FALSE;
53
54 //
55 // Set default value to assume IA-32 Architectural MSRs are used
56 //
57 UINT32 mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE;
58 UINT32 mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK;
59
60 //
61 // Set default value to assume MTRRs need to be configured on each SMI
62 //
63 BOOLEAN mNeedConfigureMtrrs = TRUE;
64
65 //
66 // Array for state of SMRR enable on all CPUs
67 //
68 BOOLEAN *mSmrrEnabled;
69
70 /**
71 The constructor function
72
73 @param[in] ImageHandle The firmware allocated handle for the EFI image.
74 @param[in] SystemTable A pointer to the EFI System Table.
75
76 @retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
77
78 **/
79 EFI_STATUS
80 EFIAPI
81 SmmCpuFeaturesLibConstructor (
82 IN EFI_HANDLE ImageHandle,
83 IN EFI_SYSTEM_TABLE *SystemTable
84 )
85 {
86 UINT32 RegEax;
87 UINT32 RegEdx;
88 UINTN FamilyId;
89 UINTN ModelId;
90
91 //
92 // Retrieve CPU Family and Model
93 //
94 AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
95 FamilyId = (RegEax >> 8) & 0xf;
96 ModelId = (RegEax >> 4) & 0xf;
97 if (FamilyId == 0x06 || FamilyId == 0x0f) {
98 ModelId = ModelId | ((RegEax >> 12) & 0xf0);
99 }
100
101 //
102 // Check CPUID(CPUID_VERSION_INFO).EDX[12] for MTRR capability
103 //
104 if ((RegEdx & BIT12) != 0) {
105 //
106 // Check MTRR_CAP MSR bit 11 for SMRR support
107 //
108 if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MTRR_CAP) & BIT11) != 0) {
109 mSmrrSupported = TRUE;
110 }
111 }
112
113 //
114 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
115 // Volume 3C, Section 35.3 MSRs in the Intel(R) Atom(TM) Processor Family
116 //
117 // If CPU Family/Model is 06_1CH, 06_26H, 06_27H, 06_35H or 06_36H, then
118 // SMRR Physical Base and SMM Physical Mask MSRs are not available.
119 //
120 if (FamilyId == 0x06) {
121 if (ModelId == 0x1C || ModelId == 0x26 || ModelId == 0x27 || ModelId == 0x35 || ModelId == 0x36) {
122 mSmrrSupported = FALSE;
123 }
124 }
125
126 //
127 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
128 // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
129 //
130 // If CPU Family/Model is 06_0F or 06_17, then use Intel(R) Core(TM) 2
131 // Processor Family MSRs
132 //
133 if (FamilyId == 0x06) {
134 if (ModelId == 0x17 || ModelId == 0x0f) {
135 mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE;
136 mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK;
137 }
138 }
139
140 //
141 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
142 // Volume 3C, Section 34.4.2 SMRAM Caching
143 // An IA-32 processor does not automatically write back and invalidate its
144 // caches before entering SMM or before exiting SMM. Because of this behavior,
145 // care must be taken in the placement of the SMRAM in system memory and in
146 // the caching of the SMRAM to prevent cache incoherence when switching back
147 // and forth between SMM and protected mode operation.
148 //
149 // An IA-32 processor is a processor that does not support the Intel 64
150 // Architecture. Support for the Intel 64 Architecture can be detected from
151 // CPUID(CPUID_EXTENDED_CPU_SIG).EDX[29]
152 //
153 // If an IA-32 processor is detected, then set mNeedConfigureMtrrs to TRUE,
154 // so caches are flushed on SMI entry and SMI exit, the interrupted code
155 // MTRRs are saved/restored, and MTRRs for SMM are loaded.
156 //
157 AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
158 if (RegEax >= CPUID_EXTENDED_CPU_SIG) {
159 AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &RegEdx);
160 if ((RegEdx & BIT29) != 0) {
161 mNeedConfigureMtrrs = FALSE;
162 }
163 }
164
165 //
166 // Allocate array for state of SMRR enable on all CPUs
167 //
168 mSmrrEnabled = (BOOLEAN *)AllocatePool (sizeof (BOOLEAN) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
169 ASSERT (mSmrrEnabled != NULL);
170
171 return EFI_SUCCESS;
172 }
173
174 /**
175 Called during the very first SMI into System Management Mode to initialize
176 CPU features, including SMBASE, for the currently executing CPU. Since this
177 is the first SMI, the SMRAM Save State Map is at the default address of
178 SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET. The currently executing
179 CPU is specified by CpuIndex and CpuIndex can be used to access information
180 about the currently executing CPU in the ProcessorInfo array and the
181 HotPlugCpuData data structure.
182
183 @param[in] CpuIndex The index of the CPU to initialize. The value
184 must be between 0 and the NumberOfCpus field in
185 the System Management System Table (SMST).
186 @param[in] IsMonarch TRUE if the CpuIndex is the index of the CPU that
187 was elected as monarch during System Management
188 Mode initialization.
189 FALSE if the CpuIndex is not the index of the CPU
190 that was elected as monarch during System
191 Management Mode initialization.
192 @param[in] ProcessorInfo Pointer to an array of EFI_PROCESSOR_INFORMATION
193 structures. ProcessorInfo[CpuIndex] contains the
194 information for the currently executing CPU.
195 @param[in] CpuHotPlugData Pointer to the CPU_HOT_PLUG_DATA structure that
196 contains the ApidId and SmBase arrays.
197 **/
198 VOID
199 EFIAPI
200 SmmCpuFeaturesInitializeProcessor (
201 IN UINTN CpuIndex,
202 IN BOOLEAN IsMonarch,
203 IN EFI_PROCESSOR_INFORMATION *ProcessorInfo,
204 IN CPU_HOT_PLUG_DATA *CpuHotPlugData
205 )
206 {
207 SMRAM_SAVE_STATE_MAP *CpuState;
208 UINT64 FeatureControl;
209 UINT32 RegEax;
210 UINT32 RegEdx;
211 UINTN FamilyId;
212 UINTN ModelId;
213
214 //
215 // Configure SMBASE.
216 //
217 CpuState = (SMRAM_SAVE_STATE_MAP *)(UINTN)(SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET);
218 CpuState->x86.SMBASE = (UINT32)CpuHotPlugData->SmBase[CpuIndex];
219
220 //
221 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
222 // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
223 //
224 // If Intel(R) Core(TM) Core(TM) 2 Processor Family MSRs are being used, then
225 // make sure SMRR Enable(BIT3) of MSR_FEATURE_CONTROL MSR(0x3A) is set before
226 // accessing SMRR base/mask MSRs. If Lock(BIT0) of MSR_FEATURE_CONTROL MSR(0x3A)
227 // is set, then the MSR is locked and can not be modified.
228 //
229 if (mSmrrSupported && mSmrrPhysBaseMsr == SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE) {
230 FeatureControl = AsmReadMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL);
231 if ((FeatureControl & BIT3) == 0) {
232 if ((FeatureControl & BIT0) == 0) {
233 AsmWriteMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL, FeatureControl | BIT3);
234 } else {
235 mSmrrSupported = FALSE;
236 }
237 }
238 }
239
240 //
241 // If SMRR is supported, then program SMRR base/mask MSRs.
242 // The EFI_MSR_SMRR_PHYS_MASK_VALID bit is not set until the first normal SMI.
243 // The code that initializes SMM environment is running in normal mode
244 // from SMRAM region. If SMRR is enabled here, then the SMRAM region
245 // is protected and the normal mode code execution will fail.
246 //
247 if (mSmrrSupported) {
248 AsmWriteMsr64 (mSmrrPhysBaseMsr, CpuHotPlugData->SmrrBase | MTRR_CACHE_WRITE_BACK);
249 AsmWriteMsr64 (mSmrrPhysMaskMsr, (~(CpuHotPlugData->SmrrSize - 1) & EFI_MSR_SMRR_MASK));
250 mSmrrEnabled[CpuIndex] = FALSE;
251 }
252
253 //
254 // Retrieve CPU Family and Model
255 //
256 AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
257 FamilyId = (RegEax >> 8) & 0xf;
258 ModelId = (RegEax >> 4) & 0xf;
259 if (FamilyId == 0x06 || FamilyId == 0x0f) {
260 ModelId = ModelId | ((RegEax >> 12) & 0xf0);
261 }
262
263 //
264 // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
265 // Volume 3C, Section 35.10.1 MSRs in 4th Generation Intel(R) Core(TM)
266 // Processor Family.
267 //
268 // If CPU Family/Model is 06_3C, 06_45, or 06_46 then use 4th Generation
269 // Intel(R) Core(TM) Processor Family MSRs.
270 //
271 if (FamilyId == 0x06) {
272 if (ModelId == 0x3C || ModelId == 0x45 || ModelId == 0x46) {
273 //
274 // Check to see if the CPU supports the SMM Code Access Check feature
275 // Do not access this MSR unless the CPU supports the SmmRegFeatureControl
276 //
277 if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MCA_CAP) & SMM_CODE_ACCESS_CHK_BIT) != 0) {
278 mSmmFeatureControlSupported = TRUE;
279 }
280 }
281 }
282 }
283
284 /**
285 This function updates the SMRAM save state on the currently executing CPU
286 to resume execution at a specific address after an RSM instruction. This
287 function must evaluate the SMRAM save state to determine the execution mode
288 the RSM instruction resumes and update the resume execution address with
289 either NewInstructionPointer32 or NewInstructionPoint. The auto HALT restart
290 flag in the SMRAM save state must always be cleared. This function returns
291 the value of the instruction pointer from the SMRAM save state that was
292 replaced. If this function returns 0, then the SMRAM save state was not
293 modified.
294
295 This function is called during the very first SMI on each CPU after
296 SmmCpuFeaturesInitializeProcessor() to set a flag in normal execution mode
297 to signal that the SMBASE of each CPU has been updated before the default
298 SMBASE address is used for the first SMI to the next CPU.
299
300 @param[in] CpuIndex The index of the CPU to hook. The value
301 must be between 0 and the NumberOfCpus
302 field in the System Management System Table
303 (SMST).
304 @param[in] CpuState Pointer to SMRAM Save State Map for the
305 currently executing CPU.
306 @param[in] NewInstructionPointer32 Instruction pointer to use if resuming to
307 32-bit execution mode from 64-bit SMM.
308 @param[in] NewInstructionPointer Instruction pointer to use if resuming to
309 same execution mode as SMM.
310
311 @retval 0 This function did modify the SMRAM save state.
312 @retval > 0 The original instruction pointer value from the SMRAM save state
313 before it was replaced.
314 **/
315 UINT64
316 EFIAPI
317 SmmCpuFeaturesHookReturnFromSmm (
318 IN UINTN CpuIndex,
319 IN SMRAM_SAVE_STATE_MAP *CpuState,
320 IN UINT64 NewInstructionPointer32,
321 IN UINT64 NewInstructionPointer
322 )
323 {
324 return 0;
325 }
326
327 /**
328 Hook point in normal execution mode that allows the one CPU that was elected
329 as monarch during System Management Mode initialization to perform additional
330 initialization actions immediately after all of the CPUs have processed their
331 first SMI and called SmmCpuFeaturesInitializeProcessor() relocating SMBASE
332 into a buffer in SMRAM and called SmmCpuFeaturesHookReturnFromSmm().
333 **/
334 VOID
335 EFIAPI
336 SmmCpuFeaturesSmmRelocationComplete (
337 VOID
338 )
339 {
340 }
341
342 /**
343 Return the size, in bytes, of a custom SMI Handler in bytes. If 0 is
344 returned, then a custom SMI handler is not provided by this library,
345 and the default SMI handler must be used.
346
347 @retval 0 Use the default SMI handler.
348 @retval > 0 Use the SMI handler installed by SmmCpuFeaturesInstallSmiHandler()
349 The caller is required to allocate enough SMRAM for each CPU to
350 support the size of the custom SMI handler.
351 **/
352 UINTN
353 EFIAPI
354 SmmCpuFeaturesGetSmiHandlerSize (
355 VOID
356 )
357 {
358 return 0;
359 }
360
361 /**
362 Install a custom SMI handler for the CPU specified by CpuIndex. This function
363 is only called if SmmCpuFeaturesGetSmiHandlerSize() returns a size is greater
364 than zero and is called by the CPU that was elected as monarch during System
365 Management Mode initialization.
366
367 @param[in] CpuIndex The index of the CPU to install the custom SMI handler.
368 The value must be between 0 and the NumberOfCpus field
369 in the System Management System Table (SMST).
370 @param[in] SmBase The SMBASE address for the CPU specified by CpuIndex.
371 @param[in] SmiStack The stack to use when an SMI is processed by the
372 the CPU specified by CpuIndex.
373 @param[in] StackSize The size, in bytes, if the stack used when an SMI is
374 processed by the CPU specified by CpuIndex.
375 @param[in] GdtBase The base address of the GDT to use when an SMI is
376 processed by the CPU specified by CpuIndex.
377 @param[in] GdtSize The size, in bytes, of the GDT used when an SMI is
378 processed by the CPU specified by CpuIndex.
379 @param[in] IdtBase The base address of the IDT to use when an SMI is
380 processed by the CPU specified by CpuIndex.
381 @param[in] IdtSize The size, in bytes, of the IDT used when an SMI is
382 processed by the CPU specified by CpuIndex.
383 @param[in] Cr3 The base address of the page tables to use when an SMI
384 is processed by the CPU specified by CpuIndex.
385 **/
386 VOID
387 EFIAPI
388 SmmCpuFeaturesInstallSmiHandler (
389 IN UINTN CpuIndex,
390 IN UINT32 SmBase,
391 IN VOID *SmiStack,
392 IN UINTN StackSize,
393 IN UINTN GdtBase,
394 IN UINTN GdtSize,
395 IN UINTN IdtBase,
396 IN UINTN IdtSize,
397 IN UINT32 Cr3
398 )
399 {
400 }
401
402 /**
403 Determines if MTRR registers must be configured to set SMRAM cache-ability
404 when executing in System Management Mode.
405
406 @retval TRUE MTRR registers must be configured to set SMRAM cache-ability.
407 @retval FALSE MTRR registers do not need to be configured to set SMRAM
408 cache-ability.
409 **/
410 BOOLEAN
411 EFIAPI
412 SmmCpuFeaturesNeedConfigureMtrrs (
413 VOID
414 )
415 {
416 return mNeedConfigureMtrrs;
417 }
418
419 /**
420 Disable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
421 returns TRUE.
422 **/
423 VOID
424 EFIAPI
425 SmmCpuFeaturesDisableSmrr (
426 VOID
427 )
428 {
429 if (mSmrrSupported && mNeedConfigureMtrrs) {
430 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) & ~EFI_MSR_SMRR_PHYS_MASK_VALID);
431 }
432 }
433
434 /**
435 Enable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
436 returns TRUE.
437 **/
438 VOID
439 EFIAPI
440 SmmCpuFeaturesReenableSmrr (
441 VOID
442 )
443 {
444 if (mSmrrSupported && mNeedConfigureMtrrs) {
445 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
446 }
447 }
448
449 /**
450 Processor specific hook point each time a CPU enters System Management Mode.
451
452 @param[in] CpuIndex The index of the CPU that has entered SMM. The value
453 must be between 0 and the NumberOfCpus field in the
454 System Management System Table (SMST).
455 **/
456 VOID
457 EFIAPI
458 SmmCpuFeaturesRendezvousEntry (
459 IN UINTN CpuIndex
460 )
461 {
462 //
463 // If SMRR is supported and this is the first normal SMI, then enable SMRR
464 //
465 if (mSmrrSupported && !mSmrrEnabled[CpuIndex]) {
466 AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64 (mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
467 mSmrrEnabled[CpuIndex] = TRUE;
468 }
469 }
470
471 /**
472 Processor specific hook point each time a CPU exits System Management Mode.
473
474 @param[in] CpuIndex The index of the CPU that is exiting SMM. The value must
475 be between 0 and the NumberOfCpus field in the System
476 Management System Table (SMST).
477 **/
478 VOID
479 EFIAPI
480 SmmCpuFeaturesRendezvousExit (
481 IN UINTN CpuIndex
482 )
483 {
484 }
485
486 /**
487 Check to see if an SMM register is supported by a specified CPU.
488
489 @param[in] CpuIndex The index of the CPU to check for SMM register support.
490 The value must be between 0 and the NumberOfCpus field
491 in the System Management System Table (SMST).
492 @param[in] RegName Identifies the SMM register to check for support.
493
494 @retval TRUE The SMM register specified by RegName is supported by the CPU
495 specified by CpuIndex.
496 @retval FALSE The SMM register specified by RegName is not supported by the
497 CPU specified by CpuIndex.
498 **/
499 BOOLEAN
500 EFIAPI
501 SmmCpuFeaturesIsSmmRegisterSupported (
502 IN UINTN CpuIndex,
503 IN SMM_REG_NAME RegName
504 )
505 {
506 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
507 return TRUE;
508 }
509 return FALSE;
510 }
511
512 /**
513 Returns the current value of the SMM register for the specified CPU.
514 If the SMM register is not supported, then 0 is returned.
515
516 @param[in] CpuIndex The index of the CPU to read the SMM register. The
517 value must be between 0 and the NumberOfCpus field in
518 the System Management System Table (SMST).
519 @param[in] RegName Identifies the SMM register to read.
520
521 @return The value of the SMM register specified by RegName from the CPU
522 specified by CpuIndex.
523 **/
524 UINT64
525 EFIAPI
526 SmmCpuFeaturesGetSmmRegister (
527 IN UINTN CpuIndex,
528 IN SMM_REG_NAME RegName
529 )
530 {
531 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
532 return AsmReadMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL);
533 }
534 return 0;
535 }
536
537 /**
538 Sets the value of an SMM register on a specified CPU.
539 If the SMM register is not supported, then no action is performed.
540
541 @param[in] CpuIndex The index of the CPU to write the SMM register. The
542 value must be between 0 and the NumberOfCpus field in
543 the System Management System Table (SMST).
544 @param[in] RegName Identifies the SMM register to write.
545 registers are read-only.
546 @param[in] Value The value to write to the SMM register.
547 **/
548 VOID
549 EFIAPI
550 SmmCpuFeaturesSetSmmRegister (
551 IN UINTN CpuIndex,
552 IN SMM_REG_NAME RegName,
553 IN UINT64 Value
554 )
555 {
556 if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
557 AsmWriteMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL, Value);
558 }
559 }
560
561 /**
562 Read an SMM Save State register on the target processor. If this function
563 returns EFI_UNSUPPORTED, then the caller is responsible for reading the
564 SMM Save Sate register.
565
566 @param[in] CpuIndex The index of the CPU to read the SMM Save State. The
567 value must be between 0 and the NumberOfCpus field in
568 the System Management System Table (SMST).
569 @param[in] Register The SMM Save State register to read.
570 @param[in] Width The number of bytes to read from the CPU save state.
571 @param[out] Buffer Upon return, this holds the CPU register value read
572 from the save state.
573
574 @retval EFI_SUCCESS The register was read from Save State.
575 @retval EFI_INVALID_PARAMTER Buffer is NULL.
576 @retval EFI_UNSUPPORTED This function does not support reading Register.
577
578 **/
579 EFI_STATUS
580 EFIAPI
581 SmmCpuFeaturesReadSaveStateRegister (
582 IN UINTN CpuIndex,
583 IN EFI_SMM_SAVE_STATE_REGISTER Register,
584 IN UINTN Width,
585 OUT VOID *Buffer
586 )
587 {
588 return EFI_UNSUPPORTED;
589 }
590
591 /**
592 Writes an SMM Save State register on the target processor. If this function
593 returns EFI_UNSUPPORTED, then the caller is responsible for writing the
594 SMM Save Sate register.
595
596 @param[in] CpuIndex The index of the CPU to write the SMM Save State. The
597 value must be between 0 and the NumberOfCpus field in
598 the System Management System Table (SMST).
599 @param[in] Register The SMM Save State register to write.
600 @param[in] Width The number of bytes to write to the CPU save state.
601 @param[in] Buffer Upon entry, this holds the new CPU register value.
602
603 @retval EFI_SUCCESS The register was written to Save State.
604 @retval EFI_INVALID_PARAMTER Buffer is NULL.
605 @retval EFI_UNSUPPORTED This function does not support writing Register.
606 **/
607 EFI_STATUS
608 EFIAPI
609 SmmCpuFeaturesWriteSaveStateRegister (
610 IN UINTN CpuIndex,
611 IN EFI_SMM_SAVE_STATE_REGISTER Register,
612 IN UINTN Width,
613 IN CONST VOID *Buffer
614 )
615 {
616 return EFI_UNSUPPORTED;
617 }