source: vbox/trunk/src/VBox/Devices/EFI/FirmwareNew/OvmfPkg/Library/SmmCpuPlatformHookLibQemu/SmmCpuPlatformHookLibQemu.c

/** @file
SMM CPU Platform Hook library instance for QEMU.

Copyright (c) 2020, Red Hat, Inc.
Copyright (c) 2006 - 2024, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/
#include <Library/BaseLib.h>                 // AsmReadMsr64()
#include <PiSmm.h>
#include <Register/Intel/ArchitecturalMsr.h> // MSR_IA32_APIC_BASE_REGISTER

#include <Library/SmmCpuPlatformHookLib.h>

/**
  Checks if platform produces a valid SMI.

  This function checks if platform produces a valid SMI. This function is
  called at SMM entry to detect if this is a spurious SMI. This function
  must be implemented in an MP safe way because it is called by multiple CPU
  threads.

  @retval TRUE              There is a valid SMI
  @retval FALSE             There is no valid SMI

**/
BOOLEAN
EFIAPI
PlatformValidSmi (
  VOID
  )
{
  return TRUE;
}

/**
  Clears platform top level SMI status bit.

  This function clears platform top level SMI status bit.

  @retval TRUE              The platform top level SMI status is cleared.
  @retval FALSE             The platform top level SMI status cannot be
                            cleared.

**/
BOOLEAN
EFIAPI
ClearTopLevelSmiStatus (
  VOID
  )
{
  return TRUE;
}

/**
  Performs platform specific way of SMM BSP election.

  This function performs platform specific way of SMM BSP election.

  @param  IsBsp             Output parameter. TRUE: the CPU this function
                            executes on is elected to be the SMM BSP. FALSE:
                            the CPU this function executes on is to be SMM AP.

  @retval EFI_SUCCESS       The function executes successfully.
  @retval EFI_NOT_READY     The function does not determine whether this CPU
                            should be BSP or AP. This may occur if hardware
                            init sequence to enable the determination is yet to
                            be done, or the function chooses not to do BSP
                            election and will let SMM CPU driver to use its
                            default BSP election process.
  @retval EFI_DEVICE_ERROR  The function cannot determine whether this CPU
                            should be BSP or AP due to hardware error.

**/
EFI_STATUS
EFIAPI
PlatformSmmBspElection (
  OUT BOOLEAN  *IsBsp
  )
{
  MSR_IA32_APIC_BASE_REGISTER  ApicBaseMsr;

  ApicBaseMsr.Uint64 = AsmReadMsr64 (MSR_IA32_APIC_BASE);
  *IsBsp             = (BOOLEAN)(ApicBaseMsr.Bits.BSP == 1);
  return EFI_SUCCESS;
}

/**
  Get platform page table attribute.

  This function gets page table attribute of platform.

  @param  Address        Input parameter. Obtain the page table entries
                         attribute on this address.
  @param  PageSize       Output parameter. The size of the page.
  @param  NumOfPages     Output parameter. Number of page.
  @param  PageAttribute  Output parameter. Paging Attributes (WB, UC, etc).

  @retval EFI_SUCCESS      The platform page table attribute from the address
                           is determined.
  @retval EFI_UNSUPPORTED  The platform does not support getting page table
                           attribute for the address.

**/
EFI_STATUS
EFIAPI
GetPlatformPageTableAttribute (
  IN  UINT64                 Address,
  IN OUT SMM_PAGE_SIZE_TYPE  *PageSize,
  IN OUT UINTN               *NumOfPages,
  IN OUT UINTN               *PageAttribute
  )
{
  return EFI_UNSUPPORTED;
}

/**
  SMM CPU Platform Hook before executing MMI Handler.

  This function can be used to perform the platform specific items before executing MMI Handler.

  @retval EFI_SUCCESS      The smm cpu platform hook before executing MMI Handler is executed successfully.
  @retval EFI_UNSUPPORTED  The smm cpu platform hook before executing MMI Handler is unsupported.

**/
EFI_STATUS
EFIAPI
SmmCpuPlatformHookBeforeMmiHandler (
  VOID
  )
{
  return EFI_UNSUPPORTED;
}

/**
  This function determines whether the first CPU Synchronization should be executed unconditionally
  when a SMI occurs.

  If the function returns true, it indicates that there is no need to check the system configuration
  and status, and the first CPU Synchronization should be executed unconditionally.

  If the function returns false, it indicates that the first CPU Synchronization is not executed
  unconditionally, and the decision to synchronize should be based on the system configuration and status.

  @retval TRUE   The first CPU Synchronization is executed unconditionally.
  @retval FALSE  The first CPU Synchronization is not executed unconditionally.

**/
BOOLEAN
EFIAPI
IsCpuSyncAlwaysNeeded (
  VOID
  )
{
  return FALSE;
}