Re: [edk2-devel] [Patch 2/2] UefiCpuPkg/PiSmmCpuDxeSmm: Enable MM MP Protocol.

["Laszlo Ersek" <lersek@redhat.com>]

On 06/19/19 07:51, Dong, Eric wrote:
> Add MM Mp Protocol in PiSmmCpuDxeSmm driver.
> 
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.c       | 375 +++++++++++++++
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.h       | 283 +++++++++++
>  UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c        | 468 ++++++++++++++++++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c   |  11 +
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h   | 172 ++++++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf |   3 +
>  6 files changed, 1296 insertions(+), 16 deletions(-)
>  create mode 100644 UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.c
>  create mode 100644 UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.h
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.c
> new file mode 100644
> index 0000000000..8cf69428c2
> --- /dev/null
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpProtocol.c
> @@ -0,0 +1,375 @@
> +/** @file
> +SMM MP protocol implementation
> +
> +Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
> +
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include "PiSmmCpuDxeSmm.h"
> +#include "MpProtocol.h"
> +
> +///
> +/// SMM MP Protocol instance
> +///
> +EFI_SMM_MP_PROTOCOL  mSmmMp  = {
> +  EFI_SMM_MP_PROTOCOL_REVISION,
> +  0,
> +  SmmMpGetNumberOfProcessors,
> +  SmmMpDispatchProcedure,
> +  SmmMpBroadcastProcedure,
> +  SmmMpSetStartupProcedure,
> +  SmmMpCheckForProcedure,
> +  SmmMpWaitForProcedure
> +};
> +
> +/**
> +  Service to retrieves the number of logical processor in the platform.
> +
> +  @param[in]  This                The EFI_MM_MP_PROTOCOL instance.
> +  @param[out] NumberOfProcessors  Pointer to the total number of logical processors in the system,
> +                                  including the BSP and all APs.
> +
> +  @retval EFI_SUCCESS             The number of processors was retrieved successfully
> +  @retval EFI_INVALID_PARAMETER   NumberOfProcessors is NULL
> +**/
> +
> +EFI_STATUS
> +EFIAPI
> +SmmMpGetNumberOfProcessors (
> +  IN CONST EFI_SMM_MP_PROTOCOL  *This,
> +  OUT      UINTN                *NumberOfProcessors
> +  )
> +{
> +  if (NumberOfProcessors == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  *NumberOfProcessors = gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus;
> +
> +  return EFI_SUCCESS;
> +}
> +
> +
> +/**
> +  This service allows the caller to invoke a procedure one of the application processors (AP). This
> +  function uses an optional token parameter to support blocking and non-blocking modes. If the token
> +  is passed into the call, the function will operate in a non-blocking fashion and the caller can
> +  check for completion with CheckOnProcedure or WaitForProcedure.
> +
> +  @param[in]     This                   The EFI_MM_MP_PROTOCOL instance.
> +  @param[in]     Procedure              A pointer to the procedure to be run on the designated target
> +                                        AP of the system. Type EFI_AP_PROCEDURE2 is defined below in
> +                                        related definitions.
> +  @param[in]     CpuNumber              The zero-based index of the processor number of the target
> +                                        AP, on which the code stream is supposed to run. If the number
> +                                        points to the calling processor then it will not run the
> +                                        supplied code.
> +  @param[in]     TimeoutInMicroseconds  Indicates the time limit in microseconds for this AP to
> +                                        finish execution of Procedure, either for blocking or
> +                                        non-blocking mode. Zero means infinity. If the timeout
> +                                        expires before this AP returns from Procedure, then Procedure
> +                                        on the AP is terminated. If the timeout expires in blocking
> +                                        mode, the call returns EFI_TIMEOUT. If the timeout expires
> +                                        in non-blocking mode, the timeout determined can be through
> +                                        CheckOnProcedure or WaitForProcedure.
> +                                        Note that timeout support is optional. Whether an
> +                                        implementation supports this feature, can be determined via
> +                                        the Attributes data member.
> +  @param[in,out] ProcedureArguments     Allows the caller to pass a list of parameters to the code
> +                                        that is run by the AP. It is an optional common mailbox
> +                                        between APs and the caller to share information.
> +  @param[in,out] Token                  This is parameter is broken into two components:
> +                                        1.Token->Completion is an optional parameter that allows the
> +                                        caller to execute the procedure in a blocking or non-blocking
> +                                        fashion. If it is NULL the call is blocking, and the call will
> +                                        not return until the AP has completed the procedure. If the
> +                                        token is not NULL, the call will return immediately. The caller
> +                                        can check whether the procedure has completed with
> +                                        CheckOnProcedure or WaitForProcedure.
> +                                        2.Token->Status The implementation updates the address pointed
> +                                        at by this variable with the status code returned by Procedure
> +                                        when it completes execution on the target AP, or with EFI_TIMEOUT
> +                                        if the Procedure fails to complete within the optional timeout.
> +                                        The implementation will update this variable with EFI_NOT_READY
> +                                        prior to starting Procedure on the target AP
> +  @param[in,out] CPUStatus              This optional pointer may be used to get the status code returned
> +                                        by Procedure when it completes execution on the target AP, or with
> +                                        EFI_TIMEOUT if the Procedure fails to complete within the optional
> +                                        timeout. The implementation will update this variable with
> +                                        EFI_NOT_READY prior to starting Procedure on the target AP.
> +
> +  @retval EFI_SUCCESS                   In the blocking case, this indicates that Procedure has completed
> +                                        execution on the target AP.
> +                                        In the non-blocking case this indicates that the procedure has
> +                                        been successfully scheduled for execution on the target AP.
> +  @retval EFI_INVALID_PARAMETER         The input arguments are out of range. Either the target AP is the
> +                                        caller of the function, or the Procedure or Token is NULL
> +  @retval EFI_NOT_READY                 If the target AP is busy executing another procedure
> +  @retval EFI_ALREADY_STARTED           Token is already in use for another procedure
> +  @retval EFI_TIMEOUT                   In blocking mode, the timeout expired before the specified AP
> +                                        has finished
> +**/
> +EFI_STATUS
> +EFIAPI
> +SmmMpDispatchProcedure (
> +  IN CONST EFI_SMM_MP_PROTOCOL           *This,
> +  IN       EFI_AP_PROCEDURE2             Procedure,
> +  IN       UINTN                         CpuNumber,
> +  IN       UINTN                         TimeoutInMicroseconds,
> +  IN OUT   VOID                          *ProcedureArguments OPTIONAL,
> +  IN OUT   SMM_COMPLETION                *Token,
> +  IN OUT   EFI_STATUS                    *CPUStatus
> +  )
> +{
> +  if (Token != NULL) {
> +    *Token = AllocatePool (sizeof (SPIN_LOCK));
> +    ASSERT (*Token != NULL);
> +    InitializeSpinLock ((SPIN_LOCK *)(*Token));
> +
> +    return InternalSmmStartupThisAp(
> +      Procedure,
> +      CpuNumber,
> +      ProcedureArguments,
> +      SmmCpuCallInNewType,
> +      (SPIN_LOCK *)(*Token),
> +      TimeoutInMicroseconds,
> +      CPUStatus
> +      );
> +  }
> +
> +  return InternalSmmStartupThisAp(
> +    Procedure,
> +    CpuNumber,
> +    ProcedureArguments,
> +    SmmCpuCallInNewType,
> +    NULL,
> +    TimeoutInMicroseconds,
> +    CPUStatus
> +    );
> +}

This function breaks the build for me:

  passing argument 1 of 'InternalSmmStartupThisAp' from incompatible
  pointer type [-Werror]

InternalSmmStartupThisAp() expects an EFI_AP_PROCEDURE as first parameter:

  typedef
  VOID
  (EFIAPI *EFI_AP_PROCEDURE)(
    IN OUT VOID  *Buffer
    );

but you pass EFI_AP_PROCEDURE2:

  typedef
  EFI_STATUS
  (EFIAPI *EFI_AP_PROCEDURE2)(
    IN VOID  *ProcedureArgument
  );

Assuming the return status propagation is otherwise correctly
implemented through "CpuStatus" -- I didn't check --, please use a
dedicated wrapper function for the callback, so that we can avoid type
punning of function pointers. (It's possible that you'll have to
introduce a separate wrapper structure too, for passing in both the
function pointer and the procedure argument pointer -- and then that
structure should be allocated dynamically.)


--*--


Independently, I think that catching "out of memory" situations in
PiSmmCpuDxeSmm with ASSERTs is bad practice. This is a privileged /
security-relevant driver, and the function in question is exposed as a
protocol member function (i.e. it's not *only* a part of driver
startup). Which I believe might make it possible for the OS, indirectly
(via EFI runtime calls for example), to trigger this function.

So, even though the PI spec doesn't list EFI_OUT_OF_RESOURCES as a valid
return code for this member function, we should return that, if
AllocatePool() fails. (This applies to SmmMpBroadcastProcedure() too.)

Thanks
Laszlo