diff options
Diffstat (limited to 'Core/UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c')
| -rw-r--r-- | Core/UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c | 630 |
1 files changed, 630 insertions, 0 deletions
diff --git a/Core/UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c b/Core/UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c new file mode 100644 index 0000000000..079baa4ae1 --- /dev/null +++ b/Core/UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c @@ -0,0 +1,630 @@ +/** @file
+The CPU specific programming for PiSmmCpuDxeSmm module.
+
+Copyright (c) 2010 - 2016, Intel Corporation. All rights reserved.<BR>
+This program and the accompanying materials
+are licensed and made available under the terms and conditions of the BSD License
+which accompanies this distribution. The full text of the license may be found at
+http://opensource.org/licenses/bsd-license.php
+
+THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <PiSmm.h>
+#include <Library/SmmCpuFeaturesLib.h>
+#include <Library/BaseLib.h>
+#include <Library/MtrrLib.h>
+#include <Library/PcdLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/DebugLib.h>
+#include <Register/Cpuid.h>
+#include <Register/SmramSaveStateMap.h>
+
+//
+// Machine Specific Registers (MSRs)
+//
+#define SMM_FEATURES_LIB_IA32_MTRR_CAP 0x0FE
+#define SMM_FEATURES_LIB_IA32_FEATURE_CONTROL 0x03A
+#define SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE 0x1F2
+#define SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK 0x1F3
+#define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE 0x0A0
+#define SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK 0x0A1
+#define EFI_MSR_SMRR_MASK 0xFFFFF000
+#define EFI_MSR_SMRR_PHYS_MASK_VALID BIT11
+#define SMM_FEATURES_LIB_SMM_FEATURE_CONTROL 0x4E0
+
+//
+// MSRs required for configuration of SMM Code Access Check
+//
+#define SMM_FEATURES_LIB_IA32_MCA_CAP 0x17D
+#define SMM_CODE_ACCESS_CHK_BIT BIT58
+
+/**
+ Internal worker function that is called to complete CPU initialization at the
+ end of SmmCpuFeaturesInitializeProcessor().
+
+**/
+VOID
+FinishSmmCpuFeaturesInitializeProcessor (
+ VOID
+ );
+
+//
+// Set default value to assume SMRR is not supported
+//
+BOOLEAN mSmrrSupported = FALSE;
+
+//
+// Set default value to assume MSR_SMM_FEATURE_CONTROL is not supported
+//
+BOOLEAN mSmmFeatureControlSupported = FALSE;
+
+//
+// Set default value to assume IA-32 Architectural MSRs are used
+//
+UINT32 mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSBASE;
+UINT32 mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_SMRR_PHYSMASK;
+
+//
+// Set default value to assume MTRRs need to be configured on each SMI
+//
+BOOLEAN mNeedConfigureMtrrs = TRUE;
+
+//
+// Array for state of SMRR enable on all CPUs
+//
+BOOLEAN *mSmrrEnabled;
+
+/**
+ The constructor function
+
+ @param[in] ImageHandle The firmware allocated handle for the EFI image.
+ @param[in] SystemTable A pointer to the EFI System Table.
+
+ @retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
+
+**/
+EFI_STATUS
+EFIAPI
+SmmCpuFeaturesLibConstructor (
+ IN EFI_HANDLE ImageHandle,
+ IN EFI_SYSTEM_TABLE *SystemTable
+ )
+{
+ UINT32 RegEax;
+ UINT32 RegEdx;
+ UINTN FamilyId;
+ UINTN ModelId;
+
+ //
+ // Retrieve CPU Family and Model
+ //
+ AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
+ FamilyId = (RegEax >> 8) & 0xf;
+ ModelId = (RegEax >> 4) & 0xf;
+ if (FamilyId == 0x06 || FamilyId == 0x0f) {
+ ModelId = ModelId | ((RegEax >> 12) & 0xf0);
+ }
+
+ //
+ // Check CPUID(CPUID_VERSION_INFO).EDX[12] for MTRR capability
+ //
+ if ((RegEdx & BIT12) != 0) {
+ //
+ // Check MTRR_CAP MSR bit 11 for SMRR support
+ //
+ if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MTRR_CAP) & BIT11) != 0) {
+ mSmrrSupported = TRUE;
+ }
+ }
+
+ //
+ // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ // Volume 3C, Section 35.3 MSRs in the Intel(R) Atom(TM) Processor Family
+ //
+ // If CPU Family/Model is 06_1CH, 06_26H, 06_27H, 06_35H or 06_36H, then
+ // SMRR Physical Base and SMM Physical Mask MSRs are not available.
+ //
+ if (FamilyId == 0x06) {
+ if (ModelId == 0x1C || ModelId == 0x26 || ModelId == 0x27 || ModelId == 0x35 || ModelId == 0x36) {
+ mSmrrSupported = FALSE;
+ }
+ }
+
+ //
+ // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
+ //
+ // If CPU Family/Model is 06_0F or 06_17, then use Intel(R) Core(TM) 2
+ // Processor Family MSRs
+ //
+ if (FamilyId == 0x06) {
+ if (ModelId == 0x17 || ModelId == 0x0f) {
+ mSmrrPhysBaseMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE;
+ mSmrrPhysMaskMsr = SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSMASK;
+ }
+ }
+
+ //
+ // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ // Volume 3C, Section 34.4.2 SMRAM Caching
+ // An IA-32 processor does not automatically write back and invalidate its
+ // caches before entering SMM or before exiting SMM. Because of this behavior,
+ // care must be taken in the placement of the SMRAM in system memory and in
+ // the caching of the SMRAM to prevent cache incoherence when switching back
+ // and forth between SMM and protected mode operation.
+ //
+ // An IA-32 processor is a processor that does not support the Intel 64
+ // Architecture. Support for the Intel 64 Architecture can be detected from
+ // CPUID(CPUID_EXTENDED_CPU_SIG).EDX[29]
+ //
+ // If an IA-32 processor is detected, then set mNeedConfigureMtrrs to TRUE,
+ // so caches are flushed on SMI entry and SMI exit, the interrupted code
+ // MTRRs are saved/restored, and MTRRs for SMM are loaded.
+ //
+ AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
+ if (RegEax >= CPUID_EXTENDED_CPU_SIG) {
+ AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &RegEdx);
+ if ((RegEdx & BIT29) != 0) {
+ mNeedConfigureMtrrs = FALSE;
+ }
+ }
+
+ //
+ // Allocate array for state of SMRR enable on all CPUs
+ //
+ mSmrrEnabled = (BOOLEAN *)AllocatePool (sizeof (BOOLEAN) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+ ASSERT (mSmrrEnabled != NULL);
+
+ return EFI_SUCCESS;
+}
+
+/**
+ Called during the very first SMI into System Management Mode to initialize
+ CPU features, including SMBASE, for the currently executing CPU. Since this
+ is the first SMI, the SMRAM Save State Map is at the default address of
+ SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET. The currently executing
+ CPU is specified by CpuIndex and CpuIndex can be used to access information
+ about the currently executing CPU in the ProcessorInfo array and the
+ HotPlugCpuData data structure.
+
+ @param[in] CpuIndex The index of the CPU to initialize. The value
+ must be between 0 and the NumberOfCpus field in
+ the System Management System Table (SMST).
+ @param[in] IsMonarch TRUE if the CpuIndex is the index of the CPU that
+ was elected as monarch during System Management
+ Mode initialization.
+ FALSE if the CpuIndex is not the index of the CPU
+ that was elected as monarch during System
+ Management Mode initialization.
+ @param[in] ProcessorInfo Pointer to an array of EFI_PROCESSOR_INFORMATION
+ structures. ProcessorInfo[CpuIndex] contains the
+ information for the currently executing CPU.
+ @param[in] CpuHotPlugData Pointer to the CPU_HOT_PLUG_DATA structure that
+ contains the ApidId and SmBase arrays.
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesInitializeProcessor (
+ IN UINTN CpuIndex,
+ IN BOOLEAN IsMonarch,
+ IN EFI_PROCESSOR_INFORMATION *ProcessorInfo,
+ IN CPU_HOT_PLUG_DATA *CpuHotPlugData
+ )
+{
+ SMRAM_SAVE_STATE_MAP *CpuState;
+ UINT64 FeatureControl;
+ UINT32 RegEax;
+ UINT32 RegEdx;
+ UINTN FamilyId;
+ UINTN ModelId;
+
+ //
+ // Configure SMBASE.
+ //
+ CpuState = (SMRAM_SAVE_STATE_MAP *)(UINTN)(SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET);
+ CpuState->x86.SMBASE = (UINT32)CpuHotPlugData->SmBase[CpuIndex];
+
+ //
+ // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ // Volume 3C, Section 35.2 MSRs in the Intel(R) Core(TM) 2 Processor Family
+ //
+ // If Intel(R) Core(TM) Core(TM) 2 Processor Family MSRs are being used, then
+ // make sure SMRR Enable(BIT3) of MSR_FEATURE_CONTROL MSR(0x3A) is set before
+ // accessing SMRR base/mask MSRs. If Lock(BIT0) of MSR_FEATURE_CONTROL MSR(0x3A)
+ // is set, then the MSR is locked and can not be modified.
+ //
+ if (mSmrrSupported && mSmrrPhysBaseMsr == SMM_FEATURES_LIB_IA32_CORE_SMRR_PHYSBASE) {
+ FeatureControl = AsmReadMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL);
+ if ((FeatureControl & BIT3) == 0) {
+ if ((FeatureControl & BIT0) == 0) {
+ AsmWriteMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL, FeatureControl | BIT3);
+ } else {
+ mSmrrSupported = FALSE;
+ }
+ }
+ }
+
+ //
+ // If SMRR is supported, then program SMRR base/mask MSRs.
+ // The EFI_MSR_SMRR_PHYS_MASK_VALID bit is not set until the first normal SMI.
+ // The code that initializes SMM environment is running in normal mode
+ // from SMRAM region. If SMRR is enabled here, then the SMRAM region
+ // is protected and the normal mode code execution will fail.
+ //
+ if (mSmrrSupported) {
+ //
+ // SMRR size cannot be less than 4-KBytes
+ // SMRR size must be of length 2^n
+ // SMRR base alignment cannot be less than SMRR length
+ //
+ if ((CpuHotPlugData->SmrrSize < SIZE_4KB) ||
+ (CpuHotPlugData->SmrrSize != GetPowerOfTwo32 (CpuHotPlugData->SmrrSize)) ||
+ ((CpuHotPlugData->SmrrBase & ~(CpuHotPlugData->SmrrSize - 1)) != CpuHotPlugData->SmrrBase)) {
+ //
+ // Print message and halt if CPU is Monarch
+ //
+ if (IsMonarch) {
+ DEBUG ((DEBUG_ERROR, "SMM Base/Size does not meet alignment/size requirement!\n"));
+ CpuDeadLoop ();
+ }
+ } else {
+ AsmWriteMsr64 (mSmrrPhysBaseMsr, CpuHotPlugData->SmrrBase | MTRR_CACHE_WRITE_BACK);
+ AsmWriteMsr64 (mSmrrPhysMaskMsr, (~(CpuHotPlugData->SmrrSize - 1) & EFI_MSR_SMRR_MASK));
+ mSmrrEnabled[CpuIndex] = FALSE;
+ }
+ }
+
+ //
+ // Retrieve CPU Family and Model
+ //
+ AsmCpuid (CPUID_VERSION_INFO, &RegEax, NULL, NULL, &RegEdx);
+ FamilyId = (RegEax >> 8) & 0xf;
+ ModelId = (RegEax >> 4) & 0xf;
+ if (FamilyId == 0x06 || FamilyId == 0x0f) {
+ ModelId = ModelId | ((RegEax >> 12) & 0xf0);
+ }
+
+ //
+ // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ // Volume 3C, Section 35.10.1 MSRs in 4th Generation Intel(R) Core(TM)
+ // Processor Family.
+ //
+ // If CPU Family/Model is 06_3C, 06_45, or 06_46 then use 4th Generation
+ // Intel(R) Core(TM) Processor Family MSRs.
+ //
+ if (FamilyId == 0x06) {
+ if (ModelId == 0x3C || ModelId == 0x45 || ModelId == 0x46) {
+ //
+ // Check to see if the CPU supports the SMM Code Access Check feature
+ // Do not access this MSR unless the CPU supports the SmmRegFeatureControl
+ //
+ if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MCA_CAP) & SMM_CODE_ACCESS_CHK_BIT) != 0) {
+ mSmmFeatureControlSupported = TRUE;
+ }
+ }
+ }
+
+ //
+ // Call internal worker function that completes the CPU initialization
+ //
+ FinishSmmCpuFeaturesInitializeProcessor ();
+}
+
+/**
+ This function updates the SMRAM save state on the currently executing CPU
+ to resume execution at a specific address after an RSM instruction. This
+ function must evaluate the SMRAM save state to determine the execution mode
+ the RSM instruction resumes and update the resume execution address with
+ either NewInstructionPointer32 or NewInstructionPoint. The auto HALT restart
+ flag in the SMRAM save state must always be cleared. This function returns
+ the value of the instruction pointer from the SMRAM save state that was
+ replaced. If this function returns 0, then the SMRAM save state was not
+ modified.
+
+ This function is called during the very first SMI on each CPU after
+ SmmCpuFeaturesInitializeProcessor() to set a flag in normal execution mode
+ to signal that the SMBASE of each CPU has been updated before the default
+ SMBASE address is used for the first SMI to the next CPU.
+
+ @param[in] CpuIndex The index of the CPU to hook. The value
+ must be between 0 and the NumberOfCpus
+ field in the System Management System Table
+ (SMST).
+ @param[in] CpuState Pointer to SMRAM Save State Map for the
+ currently executing CPU.
+ @param[in] NewInstructionPointer32 Instruction pointer to use if resuming to
+ 32-bit execution mode from 64-bit SMM.
+ @param[in] NewInstructionPointer Instruction pointer to use if resuming to
+ same execution mode as SMM.
+
+ @retval 0 This function did modify the SMRAM save state.
+ @retval > 0 The original instruction pointer value from the SMRAM save state
+ before it was replaced.
+**/
+UINT64
+EFIAPI
+SmmCpuFeaturesHookReturnFromSmm (
+ IN UINTN CpuIndex,
+ IN SMRAM_SAVE_STATE_MAP *CpuState,
+ IN UINT64 NewInstructionPointer32,
+ IN UINT64 NewInstructionPointer
+ )
+{
+ return 0;
+}
+
+/**
+ Hook point in normal execution mode that allows the one CPU that was elected
+ as monarch during System Management Mode initialization to perform additional
+ initialization actions immediately after all of the CPUs have processed their
+ first SMI and called SmmCpuFeaturesInitializeProcessor() relocating SMBASE
+ into a buffer in SMRAM and called SmmCpuFeaturesHookReturnFromSmm().
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesSmmRelocationComplete (
+ VOID
+ )
+{
+}
+
+/**
+ Determines if MTRR registers must be configured to set SMRAM cache-ability
+ when executing in System Management Mode.
+
+ @retval TRUE MTRR registers must be configured to set SMRAM cache-ability.
+ @retval FALSE MTRR registers do not need to be configured to set SMRAM
+ cache-ability.
+**/
+BOOLEAN
+EFIAPI
+SmmCpuFeaturesNeedConfigureMtrrs (
+ VOID
+ )
+{
+ return mNeedConfigureMtrrs;
+}
+
+/**
+ Disable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
+ returns TRUE.
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesDisableSmrr (
+ VOID
+ )
+{
+ if (mSmrrSupported && mNeedConfigureMtrrs) {
+ AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) & ~EFI_MSR_SMRR_PHYS_MASK_VALID);
+ }
+}
+
+/**
+ Enable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs()
+ returns TRUE.
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesReenableSmrr (
+ VOID
+ )
+{
+ if (mSmrrSupported && mNeedConfigureMtrrs) {
+ AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64(mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
+ }
+}
+
+/**
+ Processor specific hook point each time a CPU enters System Management Mode.
+
+ @param[in] CpuIndex The index of the CPU that has entered SMM. The value
+ must be between 0 and the NumberOfCpus field in the
+ System Management System Table (SMST).
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesRendezvousEntry (
+ IN UINTN CpuIndex
+ )
+{
+ //
+ // If SMRR is supported and this is the first normal SMI, then enable SMRR
+ //
+ if (mSmrrSupported && !mSmrrEnabled[CpuIndex]) {
+ AsmWriteMsr64 (mSmrrPhysMaskMsr, AsmReadMsr64 (mSmrrPhysMaskMsr) | EFI_MSR_SMRR_PHYS_MASK_VALID);
+ mSmrrEnabled[CpuIndex] = TRUE;
+ }
+}
+
+/**
+ Processor specific hook point each time a CPU exits System Management Mode.
+
+ @param[in] CpuIndex The index of the CPU that is exiting SMM. The value must
+ be between 0 and the NumberOfCpus field in the System
+ Management System Table (SMST).
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesRendezvousExit (
+ IN UINTN CpuIndex
+ )
+{
+}
+
+/**
+ Check to see if an SMM register is supported by a specified CPU.
+
+ @param[in] CpuIndex The index of the CPU to check for SMM register support.
+ The value must be between 0 and the NumberOfCpus field
+ in the System Management System Table (SMST).
+ @param[in] RegName Identifies the SMM register to check for support.
+
+ @retval TRUE The SMM register specified by RegName is supported by the CPU
+ specified by CpuIndex.
+ @retval FALSE The SMM register specified by RegName is not supported by the
+ CPU specified by CpuIndex.
+**/
+BOOLEAN
+EFIAPI
+SmmCpuFeaturesIsSmmRegisterSupported (
+ IN UINTN CpuIndex,
+ IN SMM_REG_NAME RegName
+ )
+{
+ if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
+ return TRUE;
+ }
+ return FALSE;
+}
+
+/**
+ Returns the current value of the SMM register for the specified CPU.
+ If the SMM register is not supported, then 0 is returned.
+
+ @param[in] CpuIndex The index of the CPU to read the SMM register. The
+ value must be between 0 and the NumberOfCpus field in
+ the System Management System Table (SMST).
+ @param[in] RegName Identifies the SMM register to read.
+
+ @return The value of the SMM register specified by RegName from the CPU
+ specified by CpuIndex.
+**/
+UINT64
+EFIAPI
+SmmCpuFeaturesGetSmmRegister (
+ IN UINTN CpuIndex,
+ IN SMM_REG_NAME RegName
+ )
+{
+ if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
+ return AsmReadMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL);
+ }
+ return 0;
+}
+
+/**
+ Sets the value of an SMM register on a specified CPU.
+ If the SMM register is not supported, then no action is performed.
+
+ @param[in] CpuIndex The index of the CPU to write the SMM register. The
+ value must be between 0 and the NumberOfCpus field in
+ the System Management System Table (SMST).
+ @param[in] RegName Identifies the SMM register to write.
+ registers are read-only.
+ @param[in] Value The value to write to the SMM register.
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesSetSmmRegister (
+ IN UINTN CpuIndex,
+ IN SMM_REG_NAME RegName,
+ IN UINT64 Value
+ )
+{
+ if (mSmmFeatureControlSupported && RegName == SmmRegFeatureControl) {
+ AsmWriteMsr64 (SMM_FEATURES_LIB_SMM_FEATURE_CONTROL, Value);
+ }
+}
+
+/**
+ Read an SMM Save State register on the target processor. If this function
+ returns EFI_UNSUPPORTED, then the caller is responsible for reading the
+ SMM Save Sate register.
+
+ @param[in] CpuIndex The index of the CPU to read the SMM Save State. The
+ value must be between 0 and the NumberOfCpus field in
+ the System Management System Table (SMST).
+ @param[in] Register The SMM Save State register to read.
+ @param[in] Width The number of bytes to read from the CPU save state.
+ @param[out] Buffer Upon return, this holds the CPU register value read
+ from the save state.
+
+ @retval EFI_SUCCESS The register was read from Save State.
+ @retval EFI_INVALID_PARAMTER Buffer is NULL.
+ @retval EFI_UNSUPPORTED This function does not support reading Register.
+
+**/
+EFI_STATUS
+EFIAPI
+SmmCpuFeaturesReadSaveStateRegister (
+ IN UINTN CpuIndex,
+ IN EFI_SMM_SAVE_STATE_REGISTER Register,
+ IN UINTN Width,
+ OUT VOID *Buffer
+ )
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ Writes an SMM Save State register on the target processor. If this function
+ returns EFI_UNSUPPORTED, then the caller is responsible for writing the
+ SMM Save Sate register.
+
+ @param[in] CpuIndex The index of the CPU to write the SMM Save State. The
+ value must be between 0 and the NumberOfCpus field in
+ the System Management System Table (SMST).
+ @param[in] Register The SMM Save State register to write.
+ @param[in] Width The number of bytes to write to the CPU save state.
+ @param[in] Buffer Upon entry, this holds the new CPU register value.
+
+ @retval EFI_SUCCESS The register was written to Save State.
+ @retval EFI_INVALID_PARAMTER Buffer is NULL.
+ @retval EFI_UNSUPPORTED This function does not support writing Register.
+**/
+EFI_STATUS
+EFIAPI
+SmmCpuFeaturesWriteSaveStateRegister (
+ IN UINTN CpuIndex,
+ IN EFI_SMM_SAVE_STATE_REGISTER Register,
+ IN UINTN Width,
+ IN CONST VOID *Buffer
+ )
+{
+ return EFI_UNSUPPORTED;
+}
+
+/**
+ This function is hook point called after the gEfiSmmReadyToLockProtocolGuid
+ notification is completely processed.
+**/
+VOID
+EFIAPI
+SmmCpuFeaturesCompleteSmmReadyToLock (
+ VOID
+ )
+{
+}
+
+/**
+ This API provides a method for a CPU to allocate a specific region for storing page tables.
+
+ This API can be called more once to allocate memory for page tables.
+
+ Allocates the number of 4KB pages of type EfiRuntimeServicesData and returns a pointer to the
+ allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
+ is returned. If there is not enough memory remaining to satisfy the request, then NULL is
+ returned.
+
+ This function can also return NULL if there is no preference on where the page tables are allocated in SMRAM.
+
+ @param Pages The number of 4 KB pages to allocate.
+
+ @return A pointer to the allocated buffer for page tables.
+ @retval NULL Fail to allocate a specific region for storing page tables,
+ Or there is no preference on where the page tables are allocated in SMRAM.
+
+**/
+VOID *
+EFIAPI
+SmmCpuFeaturesAllocatePageTableMemory (
+ IN UINTN Pages
+ )
+{
+ return NULL;
+}
+
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