Re: [edk2-devel] [PATCH] SecurityPkg: Add retry mechanism for tpm command

["Qi Zhang" <qi1.zhang@intel.com>]

Retry count is suggested in the spec.

PtpCrbWaitRegisterBits() already has delay.

Thanks!
Qi Zhang

-----Original Message-----
From: Kinney, Michael D <michael.d.kinney@intel.com> 
Sent: Thursday, July 28, 2022 12:38 AM
To: devel@edk2.groups.io; Yao, Jiewen <jiewen.yao@intel.com>; Zhang, Qi1 <qi1.zhang@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>
Cc: Wang, Jian J <jian.j.wang@intel.com>
Subject: RE: [edk2-devel] [PATCH] SecurityPkg: Add retry mechanism for tpm command

Why is 3 the correct retry count?

Do we need this to be configurable?

Is a delay required between retries?

What specific state is a DTPM getting into that requires this retry mechanism?  Can that state be detected?

Thanks,

Mike

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Yao, 
> Jiewen
> Sent: Wednesday, July 27, 2022 5:07 AM
> To: Zhang, Qi1 <qi1.zhang@intel.com>; devel@edk2.groups.io
> Cc: Wang, Jian J <jian.j.wang@intel.com>
> Subject: Re: [edk2-devel] [PATCH] SecurityPkg: Add retry mechanism for 
> tpm command
> 
> Thanks. Please add Bugzilla ID and add tested-by tag by the people who performed the test.
> 
> For the code, reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
> 
> > -----Original Message-----
> > From: Zhang, Qi1 <qi1.zhang@intel.com>
> > Sent: Wednesday, July 27, 2022 7:36 PM
> > To: devel@edk2.groups.io
> > Cc: Zhang, Qi1 <qi1.zhang@intel.com>; Yao, Jiewen 
> > <jiewen.yao@intel.com>; Wang, Jian J <jian.j.wang@intel.com>
> > Subject: [PATCH] SecurityPkg: Add retry mechanism for tpm command
> >
> > Signed-off-by: Qi Zhang <qi1.zhang@intel.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Jian J Wang <jian.j.wang@intel.com>
> > ---
> >  .../Library/Tpm2DeviceLibDTpm/Tpm2Ptp.c       | 107 +++++++++++-------
> >  1 file changed, 68 insertions(+), 39 deletions(-)
> >
> > diff --git a/SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2Ptp.c
> > b/SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2Ptp.c
> > index 1d99beaa10..6b5994fde2 100644
> > --- a/SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2Ptp.c
> > +++ b/SecurityPkg/Library/Tpm2DeviceLibDTpm/Tpm2Ptp.c
> > @@ -33,6 +33,11 @@ SPDX-License-Identifier: BSD-2-Clause-Patent  //
> >
> >  #define TPMCMDBUFLENGTH  0x500
> >
> >
> >
> > +//
> >
> > +// Max retry count
> >
> > +//
> >
> > +#define RETRY_CNT_MAX  3
> >
> > +
> >
> >  /**
> >
> >    Check whether TPM PTP register exist.
> >
> >
> >
> > @@ -153,6 +158,7 @@ PtpCrbTpmCommand (
> >    UINT32      TpmOutSize;
> >
> >    UINT16      Data16;
> >
> >    UINT32      Data32;
> >
> > +  UINT8       RetryCnt;
> >
> >
> >
> >    DEBUG_CODE_BEGIN ();
> >
> >    UINTN  DebugSize;
> >
> > @@ -179,53 +185,76 @@ PtpCrbTpmCommand (
> >    DEBUG_CODE_END ();
> >
> >    TpmOutSize = 0;
> >
> >
> >
> > -  //
> >
> > -  // STEP 0:
> >
> > -  // if CapCRbIdelByPass == 0, enforce Idle state before sending 
> > command
> >
> > -  //
> >
> > -  if ((GetCachedIdleByPass () == 0) && ((MmioRead32 
> > ((UINTN)&CrbReg-
> > >CrbControlStatus) & PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE) == 0)) {
> >
> > +  RetryCnt = 0;
> >
> > +  while (TRUE) {
> >
> > +    //
> >
> > +    // STEP 0:
> >
> > +    // if CapCRbIdelByPass == 0, enforce Idle state before sending 
> > + command
> >
> > +    //
> >
> > +    if ((GetCachedIdleByPass () == 0) && ((MmioRead32 
> > + ((UINTN)&CrbReg-
> > >CrbControlStatus) & PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE) == 0)) {
> >
> > +      Status = PtpCrbWaitRegisterBits (
> >
> > +                 &CrbReg->CrbControlStatus,
> >
> > +                 PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE,
> >
> > +                 0,
> >
> > +                 PTP_TIMEOUT_C
> >
> > +                 );
> >
> > +      if (EFI_ERROR (Status)) {
> >
> > +        RetryCnt++;
> >
> > +        if (RetryCnt < RETRY_CNT_MAX) {
> >
> > +          MmioWrite32 ((UINTN)&CrbReg->CrbControlRequest,
> > PTP_CRB_CONTROL_AREA_REQUEST_GO_IDLE);
> >
> > +          continue;
> >
> > +        } else {
> >
> > +          //
> >
> > +          // Try to goIdle to recover TPM
> >
> > +          //
> >
> > +          Status = EFI_DEVICE_ERROR;
> >
> > +          goto GoIdle_Exit;
> >
> > +        }
> >
> > +      }
> >
> > +    }
> >
> > +
> >
> > +    //
> >
> > +    // STEP 1:
> >
> > +    // Ready is any time the TPM is ready to receive a command, 
> > + following a
> > write
> >
> > +    // of 1 by software to Request.cmdReady, as indicated by the 
> > + Status field
> >
> > +    // being cleared to 0.
> >
> > +    //
> >
> > +    MmioWrite32 ((UINTN)&CrbReg->CrbControlRequest,
> > PTP_CRB_CONTROL_AREA_REQUEST_COMMAND_READY);
> >
> >      Status = PtpCrbWaitRegisterBits (
> >
> > -               &CrbReg->CrbControlStatus,
> >
> > -               PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE,
> >
> > +               &CrbReg->CrbControlRequest,
> >
> >                 0,
> >
> > +               PTP_CRB_CONTROL_AREA_REQUEST_COMMAND_READY,
> >
> >                 PTP_TIMEOUT_C
> >
> >                 );
> >
> >      if (EFI_ERROR (Status)) {
> >
> > -      //
> >
> > -      // Try to goIdle to recover TPM
> >
> > -      //
> >
> > -      Status = EFI_DEVICE_ERROR;
> >
> > -      goto GoIdle_Exit;
> >
> > +      RetryCnt++;
> >
> > +      if (RetryCnt < RETRY_CNT_MAX) {
> >
> > +        MmioWrite32 ((UINTN)&CrbReg->CrbControlRequest,
> > PTP_CRB_CONTROL_AREA_REQUEST_GO_IDLE);
> >
> > +        continue;
> >
> > +      } else {
> >
> > +        Status = EFI_DEVICE_ERROR;
> >
> > +        goto GoIdle_Exit;
> >
> > +      }
> >
> >      }
> >
> > -  }
> >
> >
> >
> > -  //
> >
> > -  // STEP 1:
> >
> > -  // Ready is any time the TPM is ready to receive a command, 
> > following a write
> >
> > -  // of 1 by software to Request.cmdReady, as indicated by the 
> > Status field
> >
> > -  // being cleared to 0.
> >
> > -  //
> >
> > -  MmioWrite32 ((UINTN)&CrbReg->CrbControlRequest,
> > PTP_CRB_CONTROL_AREA_REQUEST_COMMAND_READY);
> >
> > -  Status = PtpCrbWaitRegisterBits (
> >
> > -             &CrbReg->CrbControlRequest,
> >
> > -             0,
> >
> > -             PTP_CRB_CONTROL_AREA_REQUEST_COMMAND_READY,
> >
> > -             PTP_TIMEOUT_C
> >
> > -             );
> >
> > -  if (EFI_ERROR (Status)) {
> >
> > -    Status = EFI_DEVICE_ERROR;
> >
> > -    goto GoIdle_Exit;
> >
> > -  }
> >
> > +    Status = PtpCrbWaitRegisterBits (
> >
> > +               &CrbReg->CrbControlStatus,
> >
> > +               0,
> >
> > +               PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE,
> >
> > +               PTP_TIMEOUT_C
> >
> > +               );
> >
> > +    if (EFI_ERROR (Status)) {
> >
> > +      RetryCnt++;
> >
> > +      if (RetryCnt < RETRY_CNT_MAX) {
> >
> > +        MmioWrite32 ((UINTN)&CrbReg->CrbControlRequest,
> > PTP_CRB_CONTROL_AREA_REQUEST_GO_IDLE);
> >
> > +        continue;
> >
> > +      } else {
> >
> > +        Status = EFI_DEVICE_ERROR;
> >
> > +        goto GoIdle_Exit;
> >
> > +      }
> >
> > +    }
> >
> >
> >
> > -  Status = PtpCrbWaitRegisterBits (
> >
> > -             &CrbReg->CrbControlStatus,
> >
> > -             0,
> >
> > -             PTP_CRB_CONTROL_AREA_STATUS_TPM_IDLE,
> >
> > -             PTP_TIMEOUT_C
> >
> > -             );
> >
> > -  if (EFI_ERROR (Status)) {
> >
> > -    Status = EFI_DEVICE_ERROR;
> >
> > -    goto GoIdle_Exit;
> >
> > +    break;
> >
> >    }
> >
> >
> >
> >    //
> >
> > --
> > 2.26.2.windows.1
> 
> 
> 
> 
>