text: /** @file
    CPU PEI Module installs CPU Multiple Processor PPI.
  
    Copyright (c) 2015 - 2018, 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 "CpuMpPei.h"
  
  //
  // CPU MP PPI to be installed
  //
  EFI_PEI_MP_SERVICES_PPI                mMpServicesPpi = {
    PeiGetNumberOfProcessors,
    PeiGetProcessorInfo,
    PeiStartupAllAPs,
    PeiStartupThisAP,
    PeiSwitchBSP,
    PeiEnableDisableAP,
    PeiWhoAmI,
  };
  
  EFI_PEI_PPI_DESCRIPTOR           mPeiCpuMpPpiDesc = {
    (EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
    &gEfiPeiMpServicesPpiGuid,
    &mMpServicesPpi
  };
  
  /**
    This service retrieves the number of logical processor in the platform
    and the number of those logical processors that are enabled on this boot.
    This service may only be called from the BSP.
  
    This function is used to retrieve the following information:
      - The number of logical processors that are present in the system.
      - The number of enabled logical processors in the system at the instant
        this call is made.
  
    Because MP Service Ppi provides services to enable and disable processors
    dynamically, the number of enabled logical processors may vary during the
    course of a boot session.
  
    If this service is called from an AP, then EFI_DEVICE_ERROR is returned.
    If NumberOfProcessors or NumberOfEnabledProcessors is NULL, then
    EFI_INVALID_PARAMETER is returned. Otherwise, the total number of processors
    is returned in NumberOfProcessors, the number of currently enabled processor
    is returned in NumberOfEnabledProcessors, and EFI_SUCCESS is returned.
  
    @param[in]  PeiServices         An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in]  This                Pointer to this instance of the PPI.
    @param[out] NumberOfProcessors  Pointer to the total number of logical processors in
                                    the system, including the BSP and disabled APs.
    @param[out] NumberOfEnabledProcessors
                                    Number of processors in the system that are enabled.
  
    @retval EFI_SUCCESS             The number of logical processors and enabled
                                    logical processors was retrieved.
    @retval EFI_DEVICE_ERROR        The calling processor is an AP.
    @retval EFI_INVALID_PARAMETER   NumberOfProcessors is NULL.
                                    NumberOfEnabledProcessors is NULL.
  **/
  EFI_STATUS
  EFIAPI
  PeiGetNumberOfProcessors (
    IN  CONST EFI_PEI_SERVICES    **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI   *This,
    OUT UINTN                     *NumberOfProcessors,
    OUT UINTN                     *NumberOfEnabledProcessors
    )
  {
    if ((NumberOfProcessors == NULL) || (NumberOfEnabledProcessors == NULL)) {
      return EFI_INVALID_PARAMETER;
    }
  
    return MpInitLibGetNumberOfProcessors (
             NumberOfProcessors,
             NumberOfEnabledProcessors
             );
  }
  
  /**
    Gets detailed MP-related information on the requested processor at the
    instant this call is made. This service may only be called from the BSP.
  
    This service retrieves detailed MP-related information about any processor
    on the platform. Note the following:
      - The processor information may change during the course of a boot session.
      - The information presented here is entirely MP related.
  
    Information regarding the number of caches and their sizes, frequency of operation,
    slot numbers is all considered platform-related information and is not provided
    by this service.
  
    @param[in]  PeiServices         An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in]  This                Pointer to this instance of the PPI.
    @param[in]  ProcessorNumber     Pointer to the total number of logical processors in
                                    the system, including the BSP and disabled APs.
    @param[out] ProcessorInfoBuffer Number of processors in the system that are enabled.
  
    @retval EFI_SUCCESS             Processor information was returned.
    @retval EFI_DEVICE_ERROR        The calling processor is an AP.
    @retval EFI_INVALID_PARAMETER   ProcessorInfoBuffer is NULL.
    @retval EFI_NOT_FOUND           The processor with the handle specified by
                                    ProcessorNumber does not exist in the platform.
  **/
  EFI_STATUS
  EFIAPI
  PeiGetProcessorInfo (
    IN  CONST EFI_PEI_SERVICES     **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI    *This,
    IN  UINTN                      ProcessorNumber,
    OUT EFI_PROCESSOR_INFORMATION  *ProcessorInfoBuffer
    )
  {
    return MpInitLibGetProcessorInfo (ProcessorNumber, ProcessorInfoBuffer, NULL);
  }
  
  /**
    This service executes a caller provided function on all enabled APs. APs can
    run either simultaneously or one at a time in sequence. This service supports
    both blocking requests only. This service may only
    be called from the BSP.
  
    This function is used to dispatch all the enabled APs to the function specified
    by Procedure.  If any enabled AP is busy, then EFI_NOT_READY is returned
    immediately and Procedure is not started on any AP.
  
    If SingleThread is TRUE, all the enabled APs execute the function specified by
    Procedure one by one, in ascending order of processor handle number. Otherwise,
    all the enabled APs execute the function specified by Procedure simultaneously.
  
    If the timeout specified by TimeoutInMicroSeconds expires before all APs return
    from Procedure, then Procedure on the failed APs is terminated. All enabled APs
    are always available for further calls to EFI_PEI_MP_SERVICES_PPI.StartupAllAPs()
    and EFI_PEI_MP_SERVICES_PPI.StartupThisAP(). If FailedCpuList is not NULL, its
    content points to the list of processor handle numbers in which Procedure was
    terminated.
  
    Note: It is the responsibility of the consumer of the EFI_PEI_MP_SERVICES_PPI.StartupAllAPs()
    to make sure that the nature of the code that is executed on the BSP and the
    dispatched APs is well controlled. The MP Services Ppi does not guarantee
    that the Procedure function is MP-safe. Hence, the tasks that can be run in
    parallel are limited to certain independent tasks and well-controlled exclusive
    code. PEI services and Ppis may not be called by APs unless otherwise
    specified.
  
    In blocking execution mode, BSP waits until all APs finish or
    TimeoutInMicroSeconds expires.
  
    @param[in] PeiServices          An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in] This                 A pointer to the EFI_PEI_MP_SERVICES_PPI instance.
    @param[in] Procedure            A pointer to the function to be run on enabled APs of
                                    the system.
    @param[in] SingleThread         If TRUE, then all the enabled APs execute the function
                                    specified by Procedure one by one, in ascending order
                                    of processor handle number. If FALSE, then all the
                                    enabled APs execute the function specified by Procedure
                                    simultaneously.
    @param[in] TimeoutInMicroSeconds
                                    Indicates the time limit in microseconds for APs to
                                    return from Procedure, for blocking mode only. Zero
                                    means infinity. If the timeout expires before all APs
                                    return from Procedure, then Procedure on the failed APs
                                    is terminated. All enabled APs are available for next
                                    function assigned by EFI_PEI_MP_SERVICES_PPI.StartupAllAPs()
                                    or EFI_PEI_MP_SERVICES_PPI.StartupThisAP(). If the
                                    timeout expires in blocking mode, BSP returns
                                    EFI_TIMEOUT.
    @param[in] ProcedureArgument    The parameter passed into Procedure for all APs.
  
    @retval EFI_SUCCESS             In blocking mode, all APs have finished before the
                                    timeout expired.
    @retval EFI_DEVICE_ERROR        Caller processor is AP.
    @retval EFI_NOT_STARTED         No enabled APs exist in the system.
    @retval EFI_NOT_READY           Any enabled APs are busy.
    @retval EFI_TIMEOUT             In blocking mode, the timeout expired before all
                                    enabled APs have finished.
    @retval EFI_INVALID_PARAMETER   Procedure is NULL.
  **/
  EFI_STATUS
  EFIAPI
  PeiStartupAllAPs (
    IN  CONST EFI_PEI_SERVICES    **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI   *This,
    IN  EFI_AP_PROCEDURE          Procedure,
    IN  BOOLEAN                   SingleThread,
    IN  UINTN                     TimeoutInMicroSeconds,
    IN  VOID                      *ProcedureArgument      OPTIONAL
    )
  {
    return MpInitLibStartupAllAPs (
             Procedure,
             SingleThread,
             NULL,
             TimeoutInMicroSeconds,
             ProcedureArgument,
             NULL
             );
  }
  
  /**
    This service lets the caller get one enabled AP to execute a caller-provided
    function. The caller can request the BSP to wait for the completion
    of the AP. This service may only be called from the BSP.
  
    This function is used to dispatch one enabled AP to the function specified by
    Procedure passing in the argument specified by ProcedureArgument.
    The execution is in blocking mode. The BSP waits until the AP finishes or
    TimeoutInMicroSecondss expires.
  
    If the timeout specified by TimeoutInMicroseconds expires before the AP returns
    from Procedure, then execution of Procedure by the AP is terminated. The AP is
    available for subsequent calls to EFI_PEI_MP_SERVICES_PPI.StartupAllAPs() and
    EFI_PEI_MP_SERVICES_PPI.StartupThisAP().
  
    @param[in] PeiServices          An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in] This                 A pointer to the EFI_PEI_MP_SERVICES_PPI instance.
    @param[in] Procedure            A pointer to the function to be run on enabled APs of
                                    the system.
    @param[in] ProcessorNumber      The handle number of the AP. The range is from 0 to the
                                    total number of logical processors minus 1. The total
                                    number of logical processors can be retrieved by
                                    EFI_PEI_MP_SERVICES_PPI.GetNumberOfProcessors().
    @param[in] TimeoutInMicroseconds
                                    Indicates the time limit in microseconds for APs to
                                    return from Procedure, for blocking mode only. Zero
                                    means infinity. If the timeout expires before all APs
                                    return from Procedure, then Procedure on the failed APs
                                    is terminated. All enabled APs are available for next
                                    function assigned by EFI_PEI_MP_SERVICES_PPI.StartupAllAPs()
                                    or EFI_PEI_MP_SERVICES_PPI.StartupThisAP(). If the
                                    timeout expires in blocking mode, BSP returns
                                    EFI_TIMEOUT.
    @param[in] ProcedureArgument    The parameter passed into Procedure for all APs.
  
    @retval EFI_SUCCESS             In blocking mode, specified AP finished before the
                                    timeout expires.
    @retval EFI_DEVICE_ERROR        The calling processor is an AP.
    @retval EFI_TIMEOUT             In blocking mode, the timeout expired before the
                                    specified AP has finished.
    @retval EFI_NOT_FOUND           The processor with the handle specified by
                                    ProcessorNumber does not exist.
    @retval EFI_INVALID_PARAMETER   ProcessorNumber specifies the BSP or disabled AP.
    @retval EFI_INVALID_PARAMETER   Procedure is NULL.
  **/
  EFI_STATUS
  EFIAPI
  PeiStartupThisAP (
    IN  CONST EFI_PEI_SERVICES    **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI   *This,
    IN  EFI_AP_PROCEDURE          Procedure,
    IN  UINTN                     ProcessorNumber,
    IN  UINTN                     TimeoutInMicroseconds,
    IN  VOID                      *ProcedureArgument      OPTIONAL
    )
  {
    return MpInitLibStartupThisAP (
             Procedure,
             ProcessorNumber,
             NULL,
             TimeoutInMicroseconds,
             ProcedureArgument,
             NULL
             );
  }
  
  /**
    This service switches the requested AP to be the BSP from that point onward.
    This service changes the BSP for all purposes.   This call can only be performed
    by the current BSP.
  
    This service switches the requested AP to be the BSP from that point onward.
    This service changes the BSP for all purposes. The new BSP can take over the
    execution of the old BSP and continue seamlessly from where the old one left
    off.
  
    If the BSP cannot be switched prior to the return from this service, then
    EFI_UNSUPPORTED must be returned.
  
    @param[in] PeiServices          An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in] This                 A pointer to the EFI_PEI_MP_SERVICES_PPI instance.
    @param[in] ProcessorNumber      The handle number of the AP. The range is from 0 to the
                                    total number of logical processors minus 1. The total
                                    number of logical processors can be retrieved by
                                    EFI_PEI_MP_SERVICES_PPI.GetNumberOfProcessors().
    @param[in] EnableOldBSP         If TRUE, then the old BSP will be listed as an enabled
                                    AP. Otherwise, it will be disabled.
  
    @retval EFI_SUCCESS             BSP successfully switched.
    @retval EFI_UNSUPPORTED         Switching the BSP cannot be completed prior to this
                                    service returning.
    @retval EFI_UNSUPPORTED         Switching the BSP is not supported.
    @retval EFI_DEVICE_ERROR        The calling processor is an AP.
    @retval EFI_NOT_FOUND           The processor with the handle specified by
                                    ProcessorNumber does not exist.
    @retval EFI_INVALID_PARAMETER   ProcessorNumber specifies the current BSP or a disabled
                                    AP.
    @retval EFI_NOT_READY           The specified AP is busy.
  **/
  EFI_STATUS
  EFIAPI
  PeiSwitchBSP (
    IN  CONST EFI_PEI_SERVICES   **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI  *This,
    IN  UINTN                    ProcessorNumber,
    IN  BOOLEAN                  EnableOldBSP
    )
  {
    return MpInitLibSwitchBSP (ProcessorNumber, EnableOldBSP);
  }
  
  /**
    This service lets the caller enable or disable an AP from this point onward.
    This service may only be called from the BSP.
  
    This service allows the caller enable or disable an AP from this point onward.
    The caller can optionally specify the health status of the AP by Health. If
    an AP is being disabled, then the state of the disabled AP is implementation
    dependent. If an AP is enabled, then the implementation must guarantee that a
    complete initialization sequence is performed on the AP, so the AP is in a state
    that is compatible with an MP operating system.
  
    If the enable or disable AP operation cannot be completed prior to the return
    from this service, then EFI_UNSUPPORTED must be returned.
  
    @param[in] PeiServices          An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in] This                 A pointer to the EFI_PEI_MP_SERVICES_PPI instance.
    @param[in] ProcessorNumber      The handle number of the AP. The range is from 0 to the
                                    total number of logical processors minus 1. The total
                                    number of logical processors can be retrieved by
                                    EFI_PEI_MP_SERVICES_PPI.GetNumberOfProcessors().
    @param[in] EnableAP             Specifies the new state for the processor for enabled,
                                    FALSE for disabled.
    @param[in] HealthFlag           If not NULL, a pointer to a value that specifies the
                                    new health status of the AP. This flag corresponds to
                                    StatusFlag defined in EFI_PEI_MP_SERVICES_PPI.GetProcessorInfo().
                                    Only the PROCESSOR_HEALTH_STATUS_BIT is used. All other
                                    bits are ignored. If it is NULL, this parameter is
                                    ignored.
  
    @retval EFI_SUCCESS             The specified AP was enabled or disabled successfully.
    @retval EFI_UNSUPPORTED         Enabling or disabling an AP cannot be completed prior
                                    to this service returning.
    @retval EFI_UNSUPPORTED         Enabling or disabling an AP is not supported.
    @retval EFI_DEVICE_ERROR        The calling processor is an AP.
    @retval EFI_NOT_FOUND           Processor with the handle specified by ProcessorNumber
                                    does not exist.
    @retval EFI_INVALID_PARAMETER   ProcessorNumber specifies the BSP.
  **/
  EFI_STATUS
  EFIAPI
  PeiEnableDisableAP (
    IN  CONST EFI_PEI_SERVICES    **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI   *This,
    IN  UINTN                     ProcessorNumber,
    IN  BOOLEAN                   EnableAP,
    IN  UINT32                    *HealthFlag OPTIONAL
    )
  {
    return MpInitLibEnableDisableAP (ProcessorNumber, EnableAP, HealthFlag);
  }
  
  /**
    This return the handle number for the calling processor.  This service may be
    called from the BSP and APs.
  
    This service returns the processor handle number for the calling processor.
    The returned value is in the range from 0 to the total number of logical
    processors minus 1. The total number of logical processors can be retrieved
    with EFI_PEI_MP_SERVICES_PPI.GetNumberOfProcessors(). This service may be
    called from the BSP and APs. If ProcessorNumber is NULL, then EFI_INVALID_PARAMETER
    is returned. Otherwise, the current processors handle number is returned in
    ProcessorNumber, and EFI_SUCCESS is returned.
  
    @param[in]  PeiServices         An indirect pointer to the PEI Services Table
                                    published by the PEI Foundation.
    @param[in]  This                A pointer to the EFI_PEI_MP_SERVICES_PPI instance.
    @param[out] ProcessorNumber     The handle number of the AP. The range is from 0 to the
                                    total number of logical processors minus 1. The total
                                    number of logical processors can be retrieved by
                                    EFI_PEI_MP_SERVICES_PPI.GetNumberOfProcessors().
  
    @retval EFI_SUCCESS             The current processor handle number was returned in
                                    ProcessorNumber.
    @retval EFI_INVALID_PARAMETER   ProcessorNumber is NULL.
  **/
  EFI_STATUS
  EFIAPI
  PeiWhoAmI (
    IN  CONST EFI_PEI_SERVICES   **PeiServices,
    IN  EFI_PEI_MP_SERVICES_PPI  *This,
    OUT UINTN                    *ProcessorNumber
    )
  {
    return MpInitLibWhoAmI (ProcessorNumber);
  }
  
  /**
    Get GDT register value.
  
    This function is mainly for AP purpose because AP may have different GDT
    table than BSP.
  
    @param[in,out] Buffer  The pointer to private data buffer.
  
  **/
  VOID
  EFIAPI
  GetGdtr (
    IN OUT VOID *Buffer
    )
  {
    AsmReadGdtr ((IA32_DESCRIPTOR *)Buffer);
  }
  
  /**
    Initializes CPU exceptions handlers for the sake of stack switch requirement.
  
    This function is a wrapper of InitializeCpuExceptionHandlersEx. It's mainly
    for the sake of AP's init because of EFI_AP_PROCEDURE API requirement.
  
    @param[in,out] Buffer  The pointer to private data buffer.
  
  **/
  VOID
  EFIAPI
  InitializeExceptionStackSwitchHandlers (
    IN OUT VOID *Buffer
    )
  {
    CPU_EXCEPTION_INIT_DATA           *EssData;
    IA32_DESCRIPTOR                   Idtr;
    EFI_STATUS                        Status;
  
    EssData = Buffer;
    //
    // We don't plan to replace IDT table with a new one, but we should not assume
    // the AP's IDT is the same as BSP's IDT either.
    //
    AsmReadIdtr (&Idtr);
    EssData->Ia32.IdtTable = (VOID *)Idtr.Base;
    EssData->Ia32.IdtTableSize = Idtr.Limit + 1;
    Status = InitializeCpuExceptionHandlersEx (NULL, EssData);
    ASSERT_EFI_ERROR (Status);
  }
  
  /**
    Initializes MP exceptions handlers for the sake of stack switch requirement.
  
    This function will allocate required resources required to setup stack switch
    and pass them through CPU_EXCEPTION_INIT_DATA to each logic processor.
  
  **/
  VOID
  InitializeMpExceptionStackSwitchHandlers (
    VOID
    )
  {
    EFI_STATUS                      Status;
    UINTN                           Index;
    UINTN                           Bsp;
    UINTN                           ExceptionNumber;
    UINTN                           OldGdtSize;
    UINTN                           NewGdtSize;
    UINTN                           NewStackSize;
    IA32_DESCRIPTOR                 Gdtr;
    CPU_EXCEPTION_INIT_DATA         EssData;
    UINT8                           *GdtBuffer;
    UINT8                           *StackTop;
    UINTN                           NumberOfProcessors;
  
    if (!PcdGetBool (PcdCpuStackGuard)) {
      return;
    }
  
    MpInitLibGetNumberOfProcessors(&NumberOfProcessors, NULL);
    MpInitLibWhoAmI (&Bsp);
  
    ExceptionNumber = FixedPcdGetSize (PcdCpuStackSwitchExceptionList);
    NewStackSize = FixedPcdGet32 (PcdCpuKnownGoodStackSize) * ExceptionNumber;
  
    Status = PeiServicesAllocatePool (
               NewStackSize * NumberOfProcessors,
               (VOID **)&StackTop
               );
    ASSERT(StackTop != NULL);
    if (EFI_ERROR (Status)) {
      ASSERT_EFI_ERROR (Status);
      return;
    }
    StackTop += NewStackSize  * NumberOfProcessors;
  
    //
    // The default exception handlers must have been initialized. Let's just skip
    // it in this method.
    //
    EssData.Ia32.Revision = CPU_EXCEPTION_INIT_DATA_REV;
    EssData.Ia32.InitDefaultHandlers = FALSE;
  
    EssData.Ia32.StackSwitchExceptions = FixedPcdGetPtr(PcdCpuStackSwitchExceptionList);
    EssData.Ia32.StackSwitchExceptionNumber = ExceptionNumber;
    EssData.Ia32.KnownGoodStackSize = FixedPcdGet32(PcdCpuKnownGoodStackSize);
  
    //
    // Initialize Gdtr to suppress incorrect compiler/analyzer warnings.
    //
    Gdtr.Base = 0;
    Gdtr.Limit = 0;
    for (Index = 0; Index < NumberOfProcessors; ++Index) {
      //
      // To support stack switch, we need to re-construct GDT but not IDT.
      //
      if (Index == Bsp) {
        GetGdtr(&Gdtr);
      } else {
        //
        // AP might have different size of GDT from BSP.
        //
        MpInitLibStartupThisAP (GetGdtr, Index, NULL, 0, (VOID *)&Gdtr, NULL);
      }
  
      //
      // X64 needs only one TSS of current task working for all exceptions
      // because of its IST feature. IA32 needs one TSS for each exception
      // in addition to current task. Since AP is not supposed to allocate
      // memory, we have to do it in BSP. To simplify the code, we allocate
      // memory for IA32 case to cover both IA32 and X64 exception stack
      // switch.
      //
      // Layout of memory to allocate for each processor:
      //    --------------------------------
      //    |            Alignment         |  (just in case)
      //    --------------------------------
      //    |                              |
      //    |        Original GDT          |
      //    |                              |
      //    --------------------------------
      //    |    Current task descriptor   |
      //    --------------------------------
      //    |                              |
      //    |  Exception task descriptors  |  X ExceptionNumber
      //    |                              |
      //    --------------------------------
      //    |  Current task-state segment  |
      //    --------------------------------
      //    |                              |
      //    | Exception task-state segment |  X ExceptionNumber
      //    |                              |
      //    --------------------------------
      //
      OldGdtSize = Gdtr.Limit + 1;
      EssData.Ia32.ExceptionTssDescSize = sizeof (IA32_TSS_DESCRIPTOR) *
                                          (ExceptionNumber + 1);
      EssData.Ia32.ExceptionTssSize = sizeof (IA32_TASK_STATE_SEGMENT) *
                                      (ExceptionNumber + 1);
      NewGdtSize = sizeof (IA32_TSS_DESCRIPTOR) +
                   OldGdtSize +
                   EssData.Ia32.ExceptionTssDescSize +
                   EssData.Ia32.ExceptionTssSize;
  
      Status = PeiServicesAllocatePool (
                 NewGdtSize,
                 (VOID **)&GdtBuffer
                 );
      ASSERT (GdtBuffer != NULL);
      if (EFI_ERROR (Status)) {
        ASSERT_EFI_ERROR (Status);
        return;
      }
  
      //
      // Make sure GDT table alignment
      //
      EssData.Ia32.GdtTable = ALIGN_POINTER(GdtBuffer, sizeof (IA32_TSS_DESCRIPTOR));
      NewGdtSize -= ((UINT8 *)EssData.Ia32.GdtTable - GdtBuffer);
      EssData.Ia32.GdtTableSize = NewGdtSize;
  
      EssData.Ia32.ExceptionTssDesc = ((UINT8 *)EssData.Ia32.GdtTable + OldGdtSize);
      EssData.Ia32.ExceptionTss = ((UINT8 *)EssData.Ia32.GdtTable + OldGdtSize +
                                   EssData.Ia32.ExceptionTssDescSize);
  
      EssData.Ia32.KnownGoodStackTop = (UINTN)StackTop;
      DEBUG ((DEBUG_INFO,
              "Exception stack top[cpu%lu]: 0x%lX\n",
              (UINT64)(UINTN)Index,
              (UINT64)(UINTN)StackTop));
  
      if (Index == Bsp) {
        InitializeExceptionStackSwitchHandlers (&EssData);
      } else {
        MpInitLibStartupThisAP (
          InitializeExceptionStackSwitchHandlers,
          Index,
          NULL,
          0,
          (VOID *)&EssData,
          NULL
          );
      }
  
      StackTop  -= NewStackSize;
    }
  }
  
  /**
    Initializes MP and exceptions handlers.
  
    @param  PeiServices                The pointer to the PEI Services Table.
  
    @retval EFI_SUCCESS     MP was successfully initialized.
    @retval others          Error occurred in MP initialization.
  
  **/
  EFI_STATUS
  InitializeCpuMpWorker (
    IN CONST EFI_PEI_SERVICES     **PeiServices
    )
  {
    EFI_STATUS                      Status;
    EFI_VECTOR_HANDOFF_INFO         *VectorInfo;
    EFI_PEI_VECTOR_HANDOFF_INFO_PPI *VectorHandoffInfoPpi;
  
    //
    // Get Vector Hand-off Info PPI
    //
    VectorInfo = NULL;
    Status = PeiServicesLocatePpi (
               &gEfiVectorHandoffInfoPpiGuid,
               0,
               NULL,
               (VOID **)&VectorHandoffInfoPpi
               );
    if (Status == EFI_SUCCESS) {
      VectorInfo = VectorHandoffInfoPpi->Info;
    }
  
    //
    // Initialize default handlers
    //
    Status = InitializeCpuExceptionHandlers (VectorInfo);
    if (EFI_ERROR (Status)) {
      return Status;
    }
  
    Status = MpInitLibInitialize ();
    if (EFI_ERROR (Status)) {
      return Status;
    }
  
    //
    // Special initialization for the sake of Stack Guard
    //
    InitializeMpExceptionStackSwitchHandlers ();
  
    //
    // Update and publish CPU BIST information
    //
    CollectBistDataFromPpi (PeiServices);
  
    //
    // Install CPU MP PPI
    //
    Status = PeiServicesInstallPpi(&mPeiCpuMpPpiDesc);
    ASSERT_EFI_ERROR (Status);
  
    return Status;
  }
  
  /**
    The Entry point of the MP CPU PEIM.
  
    This function will wakeup APs and collect CPU AP count and install the
    Mp Service Ppi.
  
    @param  FileHandle    Handle of the file being invoked.
    @param  PeiServices   Describes the list of possible PEI Services.
  
    @retval EFI_SUCCESS   MpServicePpi is installed successfully.
  
  **/
  EFI_STATUS
  EFIAPI
  CpuMpPeimInit (
    IN       EFI_PEI_FILE_HANDLE  FileHandle,
    IN CONST EFI_PEI_SERVICES     **PeiServices
    )
  {
    EFI_STATUS           Status;
  
    //
    // For the sake of special initialization needing to be done right after
    // memory discovery.
    //
    Status = PeiServicesNotifyPpi (&mPostMemNotifyList[0]);
    ASSERT_EFI_ERROR (Status);
  
    return Status;
  }
  