Enumerations
enum	SMM_REG_NAME { SmmRegFeatureControl, SmmRegSmmEnable, SmmRegSmmDelayed, SmmRegSmmBlocked }

Functions
VOID EFIAPI	SmmCpuFeaturesInitializeProcessor (IN UINTN CpuIndex, IN BOOLEAN IsMonarch, IN EFI_PROCESSOR_INFORMATION ProcessorInfo, IN CPU_HOT_PLUG_DATA CpuHotPlugData)

UINT64 EFIAPI	SmmCpuFeaturesHookReturnFromSmm (IN UINTN CpuIndex, IN SMRAM_SAVE_STATE_MAP *CpuState, IN UINT64 NewInstructionPointer32, IN UINT64 NewInstructionPointer)

VOID EFIAPI	SmmCpuFeaturesSmmRelocationComplete (VOID)

UINTN EFIAPI	SmmCpuFeaturesGetSmiHandlerSize (VOID)

VOID EFIAPI	SmmCpuFeaturesInstallSmiHandler (IN UINTN CpuIndex, IN UINT32 SmBase, IN VOID *SmiStack, IN UINTN StackSize, IN UINTN GdtBase, IN UINTN GdtSize, IN UINTN IdtBase, IN UINTN IdtSize, IN UINT32 Cr3)

BOOLEAN EFIAPI	SmmCpuFeaturesNeedConfigureMtrrs (VOID)

VOID EFIAPI	SmmCpuFeaturesDisableSmrr (VOID)

VOID EFIAPI	SmmCpuFeaturesReenableSmrr (VOID)

VOID EFIAPI	SmmCpuFeaturesRendezvousEntry (IN UINTN CpuIndex)

VOID EFIAPI	SmmCpuFeaturesRendezvousExit (IN UINTN CpuIndex)

BOOLEAN EFIAPI	SmmCpuFeaturesIsSmmRegisterSupported (IN UINTN CpuIndex, IN SMM_REG_NAME RegName)

UINT64 EFIAPI	SmmCpuFeaturesGetSmmRegister (IN UINTN CpuIndex, IN SMM_REG_NAME RegName)

VOID EFIAPI	SmmCpuFeaturesSetSmmRegister (IN UINTN CpuIndex, IN SMM_REG_NAME RegName, IN UINT64 Value)

EFI_STATUS EFIAPI	SmmCpuFeaturesReadSaveStateRegister (IN UINTN CpuIndex, IN EFI_SMM_SAVE_STATE_REGISTER Register, IN UINTN Width, OUT VOID *Buffer)

EFI_STATUS EFIAPI	SmmCpuFeaturesWriteSaveStateRegister (IN UINTN CpuIndex, IN EFI_SMM_SAVE_STATE_REGISTER Register, IN UINTN Width, IN CONST VOID *Buffer)

VOID EFIAPI	SmmCpuFeaturesCompleteSmmReadyToLock (VOID)

VOID *EFIAPI	SmmCpuFeaturesAllocatePageTableMemory (IN UINTN Pages)

Detailed Description

Library that provides CPU specific functions to support the PiSmmCpuDxeSmm module.

Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Enumeration Type Documentation

enum SMM_REG_NAME

Enumeration of SMM registers that are accessed using the library functions SmmCpuFeaturesIsSmmRegisterSupported (), SmmCpuFeaturesGetSmmRegister (), and SmmCpuFeaturesSetSmmRegister ().

Enumerator
SmmRegFeatureControl	Read-write register to provides access to MSR_SMM_FEATURE_CONTROL if the CPU supports this MSR.
SmmRegSmmEnable	Read-only register that returns a non-zero value if the CPU is able to respond to SMIs.
SmmRegSmmDelayed	Read-only register that returns a non-zero value if the CPU is able to respond to SMIs, but is busy with other actions that are causing a delay in responding to an SMI. This register abstracts access to MSR_SMM_DELAYED if the CPU supports this MSR.
SmmRegSmmBlocked	Read-only register that returns a non-zero value if the CPU is able to respond to SMIs, but is busy with other actions that are blocking its ability to respond to an SMI. This register abstracts access to MSR_SMM_BLOCKED if the CPU supports this MSR.

Function Documentation

VOID* EFIAPI SmmCpuFeaturesAllocatePageTableMemory ( IN UINTN Pages )

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.

Parameters

Pages The number of 4 KB pages to allocate.

Returns: A pointer to the allocated buffer for page tables.

Return values

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 SmmCpuFeaturesCompleteSmmReadyToLock ( VOID )

This function is hook point called after the gEfiSmmReadyToLockProtocolGuid notification is completely processed.

VOID EFIAPI SmmCpuFeaturesDisableSmrr ( VOID )

Disable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs() returns TRUE.

UINTN EFIAPI SmmCpuFeaturesGetSmiHandlerSize ( VOID )

Return the size, in bytes, of a custom SMI Handler in bytes. If 0 is returned, then a custom SMI handler is not provided by this library, and the default SMI handler must be used.

Return values

0	Use the default SMI handler.
>	0 Use the SMI handler installed by SmmCpuFeaturesInstallSmiHandler() The caller is required to allocate enough SMRAM for each CPU to support the size of the custom SMI handler.

UINT64 EFIAPI SmmCpuFeaturesGetSmmRegister	(	IN UINTN	CpuIndex,
		IN SMM_REG_NAME	RegName
	)

Returns the current value of the SMM register for the specified CPU. If the SMM register is not supported, then 0 is returned.

Parameters

[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).
[in]	RegName	Identifies the SMM register to read.

Returns: The value of the SMM register specified by RegName from the CPU specified by CpuIndex.

UINT64 EFIAPI SmmCpuFeaturesHookReturnFromSmm	(	IN UINTN	CpuIndex,
		IN SMRAM_SAVE_STATE_MAP *	CpuState,
		IN UINT64	NewInstructionPointer32,
		IN UINT64	NewInstructionPointer
	)

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.

Parameters

[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).
[in]	CpuState	Pointer to SMRAM Save State Map for the currently executing CPU.
[in]	NewInstructionPointer32	Instruction pointer to use if resuming to 32-bit execution mode from 64-bit SMM.
[in]	NewInstructionPointer	Instruction pointer to use if resuming to same execution mode as SMM.

Return values

0	This function did modify the SMRAM save state.
>	0 The original instruction pointer value from the SMRAM save state before it was replaced.

VOID EFIAPI SmmCpuFeaturesInitializeProcessor	(	IN UINTN	CpuIndex,
		IN BOOLEAN	IsMonarch,
		IN EFI_PROCESSOR_INFORMATION *	ProcessorInfo,
		IN CPU_HOT_PLUG_DATA *	CpuHotPlugData
	)

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.

Parameters

[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).
[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.
[in]	ProcessorInfo	Pointer to an array of EFI_PROCESSOR_INFORMATION structures. ProcessorInfo[CpuIndex] contains the information for the currently executing CPU.
[in]	CpuHotPlugData	Pointer to the CPU_HOT_PLUG_DATA structure that contains the ApidId and SmBase arrays.

VOID EFIAPI SmmCpuFeaturesInstallSmiHandler	(	IN UINTN	CpuIndex,
		IN UINT32	SmBase,
		IN VOID *	SmiStack,
		IN UINTN	StackSize,
		IN UINTN	GdtBase,
		IN UINTN	GdtSize,
		IN UINTN	IdtBase,
		IN UINTN	IdtSize,
		IN UINT32	Cr3
	)

Install a custom SMI handler for the CPU specified by CpuIndex. This function is only called if SmmCpuFeaturesGetSmiHandlerSize() returns a size is greater than zero and is called by the CPU that was elected as monarch during System Management Mode initialization.

Append Shadow Stack after normal stack

|= SmiStack +-----------------------------------------------—+------------------------------------------------------------—+ | Known Good Stack | Guard Page | SMM Stack | Known Good Shadow Stack | Guard Page | SMM Shadow Stack | +-----------------------------------------------—+------------------------------------------------------------—+ | |PcdCpuSmmStackSize| |PcdCpuSmmShadowStackSize| |<-----------------— StackSize --------------—>|<----------------------— ShadowStackSize ----------------—>| | | |<-----------------------------------------— Processor N ----------------------------------------------------—>| | low address (bottom) high address (top) |

Parameters

[in]	CpuIndex	The index of the CPU to install the custom SMI handler. The value must be between 0 and the NumberOfCpus field in the System Management System Table (SMST).
[in]	SmBase	The SMBASE address for the CPU specified by CpuIndex.
[in]	SmiStack	The bottom of stack to use when an SMI is processed by the the CPU specified by CpuIndex.
[in]	StackSize	The size, in bytes, if the stack used when an SMI is processed by the CPU specified by CpuIndex. StackSize should be PcdCpuSmmStackSize, with 2 more pages if PcdCpuSmmStackGuard is true. If ShadowStack is enabled, the shadow stack is allocated after the normal Stack. The size is PcdCpuSmmShadowStackSize. with 2 more pages if PcdCpuSmmStackGuard is true.
[in]	GdtBase	The base address of the GDT to use when an SMI is processed by the CPU specified by CpuIndex.
[in]	GdtSize	The size, in bytes, of the GDT used when an SMI is processed by the CPU specified by CpuIndex.
[in]	IdtBase	The base address of the IDT to use when an SMI is processed by the CPU specified by CpuIndex.
[in]	IdtSize	The size, in bytes, of the IDT used when an SMI is processed by the CPU specified by CpuIndex.
[in]	Cr3	The base address of the page tables to use when an SMI is processed by the CPU specified by CpuIndex.

BOOLEAN EFIAPI SmmCpuFeaturesIsSmmRegisterSupported	(	IN UINTN	CpuIndex,
		IN SMM_REG_NAME	RegName
	)

Check to see if an SMM register is supported by a specified CPU.

Parameters

[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).
[in]	RegName	Identifies the SMM register to check for support.

Return values

TRUE	The SMM register specified by RegName is supported by the CPU specified by CpuIndex.
FALSE	The SMM register specified by RegName is not supported by the CPU specified by CpuIndex.

BOOLEAN EFIAPI SmmCpuFeaturesNeedConfigureMtrrs ( VOID )

Determines if MTRR registers must be configured to set SMRAM cache-ability when executing in System Management Mode.

Return values

TRUE	MTRR registers must be configured to set SMRAM cache-ability.
FALSE	MTRR registers do not need to be configured to set SMRAM cache-ability.

EFI_STATUS EFIAPI SmmCpuFeaturesReadSaveStateRegister	(	IN UINTN	CpuIndex,
		IN EFI_SMM_SAVE_STATE_REGISTER	Register,
		IN UINTN	Width,
		OUT VOID *	Buffer
	)

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.

Parameters

[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).
[in]	Register	The SMM Save State register to read.
[in]	Width	The number of bytes to read from the CPU save state.
[out]	Buffer	Upon return, this holds the CPU register value read from the save state.

Return values

EFI_SUCCESS	The register was read from Save State.
EFI_INVALID_PARAMETER	Buffer is NULL.
EFI_UNSUPPORTED	This function does not support reading Register.

VOID EFIAPI SmmCpuFeaturesReenableSmrr ( VOID )

Enable SMRR register if SMRR is supported and SmmCpuFeaturesNeedConfigureMtrrs() returns TRUE.

VOID EFIAPI SmmCpuFeaturesRendezvousEntry ( IN UINTN CpuIndex )

Processor specific hook point each time a CPU enters System Management Mode.

Parameters

[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 SmmCpuFeaturesRendezvousExit ( IN UINTN CpuIndex )

Processor specific hook point each time a CPU exits System Management Mode.

Parameters

[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 SmmCpuFeaturesSetSmmRegister	(	IN UINTN	CpuIndex,
		IN SMM_REG_NAME	RegName,
		IN UINT64	Value
	)

Sets the value of an SMM register on a specified CPU. If the SMM register is not supported, then no action is performed.

Parameters

[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).
[in]	RegName	Identifies the SMM register to write. registers are read-only.
[in]	Value	The value to write to the SMM register.

VOID EFIAPI SmmCpuFeaturesSmmRelocationComplete ( VOID )

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().

EFI_STATUS EFIAPI SmmCpuFeaturesWriteSaveStateRegister	(	IN UINTN	CpuIndex,
		IN EFI_SMM_SAVE_STATE_REGISTER	Register,
		IN UINTN	Width,
		IN CONST VOID *	Buffer
	)

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.

Parameters

[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).
[in]	Register	The SMM Save State register to write.
[in]	Width	The number of bytes to write to the CPU save state.
[in]	Buffer	Upon entry, this holds the new CPU register value.

Return values

EFI_SUCCESS	The register was written to Save State.
EFI_INVALID_PARAMETER	Buffer is NULL.
EFI_UNSUPPORTED	This function does not support writing Register.

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

Function Documentation