Smbase.c File Reference

#include <Base.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/LocalApicLib.h>
#include <Library/SynchronizationLib.h>
#include <Register/Intel/SmramSaveStateMap.h>
#include "FirstSmiHandlerContext.h"
#include "Smbase.h"

Go to the source code of this file.

Functions
EFI_STATUS	SmbaseAllocatePostSmmPen (OUT UINT32 *PenAddress, IN CONST EFI_BOOT_SERVICES *BootServices)
VOID	SmbaseReinstallPostSmmPen (IN UINT32 PenAddress)
VOID	SmbaseReleasePostSmmPen (IN UINT32 PenAddress, IN CONST EFI_BOOT_SERVICES *BootServices)
VOID	SmbaseInstallFirstSmiHandler (VOID)
EFI_STATUS	SmbaseRelocate (IN APIC_ID ApicId, IN UINTN Smbase, IN UINT32 PenAddress)

Variables
CONST UINT8	mPostSmmPen []
CONST UINT16	mPostSmmPenSize
CONST UINT8	mFirstSmiHandler []
CONST UINT16	mFirstSmiHandlerSize

Detailed Description

SMBASE relocation for hot-plugged CPUs.

Copyright (c) 2020, Red Hat, Inc.

SPDX-License-Identifier: BSD-2-Clause-Patent

Definition in file Smbase.c.

Function Documentation

SmbaseAllocatePostSmmPen()

EFI_STATUS SmbaseAllocatePostSmmPen	(	OUT UINT32 *	PenAddress,
		IN CONST EFI_BOOT_SERVICES *	BootServices
	)

Allocate a non-SMRAM reserved memory page for the Post-SMM Pen for hot-added CPUs.

This function may only be called from the entry point function of the driver.

Parameters

[out]	PenAddress	The address of the allocated (normal RAM) reserved page.
[in]	BootServices	Pointer to the UEFI boot services table. Used for allocating the normal RAM (not SMRAM) reserved page.

Return values

EFI_SUCCESS	Allocation successful.
EFI_BAD_BUFFER_SIZE	The Post-SMM Pen template is not smaller than EFI_PAGE_SIZE.

Returns

Error codes propagated from underlying services. DEBUG_ERROR messages have been logged. No resources have been allocated.

Definition at line 48 of file Smbase.c.

SmbaseInstallFirstSmiHandler()

VOID SmbaseInstallFirstSmiHandler

(

VOID

)

Place the handler routine for the first SMIs of hot-added CPUs at (SMM_DEFAULT_SMBASE + SMM_HANDLER_OFFSET).

Note that this effects an "SMRAM to SMRAM" copy.

Additionally, shut the APIC ID gate in FIRST_SMI_HANDLER_CONTEXT.

This function may only be called from the entry point function of the driver, and only after PcdQ35SmramAtDefaultSmbase has been determined to be TRUE.

Definition at line 141 of file Smbase.c.

SmbaseReinstallPostSmmPen()

VOID SmbaseReinstallPostSmmPen

(

IN UINT32

PenAddress

)

Copy the Post-SMM Pen template code into the reserved page allocated with SmbaseAllocatePostSmmPen().

Note that this effects an "SMRAM to normal RAM" copy.

The SMM Monarch is supposed to call this function from the root MMI handler.

Parameters

[in]

PenAddress

The allocation address returned by SmbaseAllocatePostSmmPen().

Definition at line 101 of file Smbase.c.

SmbaseReleasePostSmmPen()

VOID SmbaseReleasePostSmmPen	(	IN UINT32	PenAddress,
		IN CONST EFI_BOOT_SERVICES *	BootServices
	)

Release the reserved page allocated with SmbaseAllocatePostSmmPen().

This function may only be called from the entry point function of the driver, on the error path.

Parameters

[in]	PenAddress	The allocation address returned by SmbaseAllocatePostSmmPen().
[in]	BootServices	Pointer to the UEFI boot services table. Used for releasing the normal RAM (not SMRAM) reserved page.

Definition at line 121 of file Smbase.c.

SmbaseRelocate()

EFI_STATUS SmbaseRelocate	(	IN APIC_ID	ApicId,
		IN UINTN	Smbase,
		IN UINT32	PenAddress
	)

Relocate the SMBASE on a hot-added CPU. Then pen the hot-added CPU in the normal RAM reserved memory page, set up earlier with SmbaseAllocatePostSmmPen() and SmbaseReinstallPostSmmPen().

The SMM Monarch is supposed to call this function from the root MMI handler.

The SMM Monarch is responsible for calling SmbaseInstallFirstSmiHandler(), SmbaseAllocatePostSmmPen(), and SmbaseReinstallPostSmmPen() before calling this function.

If the OS maliciously boots the hot-added CPU ahead of letting the ACPI CPU hotplug event handler broadcast the CPU hotplug MMI, then the hot-added CPU returns to the OS rather than to the pen, upon RSM. In that case, this function will hang forever (unless the OS happens to signal back through the last byte of the pen page).

Parameters

[in]	ApicId	The APIC ID of the hot-added CPU whose SMBASE should be relocated.
[in]	Smbase	The new SMBASE address. The root MMI handler is responsible for passing in a free ("unoccupied") SMBASE address that was pre-configured by PiSmmCpuDxeSmm in CPU_HOT_PLUG_DATA.
[in]	PenAddress	The address of the Post-SMM Pen for hot-added CPUs, as returned by SmbaseAllocatePostSmmPen(), and installed by SmbaseReinstallPostSmmPen().

Return values

EFI_SUCCESS	The SMBASE of the hot-added CPU with APIC ID ApicId has been relocated to Smbase. The hot-added CPU has reported back about leaving SMM.
EFI_PROTOCOL_ERROR	Synchronization bug encountered around FIRST_SMI_HANDLER_CONTEXT.ApicIdGate.
EFI_INVALID_PARAMETER	Smbase does not fit in 32 bits. No relocation has been attempted.

Definition at line 198 of file Smbase.c.