Re: [PATCH v2 10/12] OvmfPkg/LsiScsiDxe: Process the SCSI Request Packet

["Gary Lin" <glin@suse.com>]

On Thu, Jul 16, 2020 at 07:37:09PM +0200, Laszlo Ersek wrote:
> On 07/16/20 09:46, Gary Lin wrote:
> > This is the second part of LsiScsiPassThru(). LsiScsiProcessRequest() is
> > added to translate the SCSI Request Packet into the LSI 53C895A
> > commands. This function utilizes the so-called Script buffer to transmit
> > a series of commands to the chip and then polls the DMA Status (DSTAT)
> > register until the Scripts Interrupt Instruction Received (SIR) bit
> > sets. Once the script is done, the SCSI Request Packet will be modified
> > to reflect the result of the script.
> > 
> > v2:
> >   - Use the BITx macros for the most of LSI_* constants
> >   - Fix a typo: contorller => controller
> >   - Add SeaBIOS lsi-scsi driver as one of the references of the script
> >   - Cast the result of sizeof to UINT32 for the instructions of the
> >     script
> >   - Drop the backslashes
> >   - Replace LSI_SCSI_DMA_ADDR_LOW with LSI_SCSI_DMA_ADDR since we
> >     already removed DUAL_ADDRESS_CYCLE
> >   - Add more comments for the script
> >   - Fix the check of the script size at the end of the script
> >   - Always set SenseDataLength to 0 to avoid the caller to access
> >     SenseData
> >   - Improve the error handling in LsiScsiProcessRequest()
> > 
> > Cc: Jordan Justen <jordan.l.justen@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
> > Signed-off-by: Gary Lin <glin@suse.com>
> > ---
> >  OvmfPkg/Include/IndustryStandard/LsiScsi.h |  63 ++++
> >  OvmfPkg/LsiScsiDxe/LsiScsi.c               | 336 ++++++++++++++++++++-
> >  OvmfPkg/LsiScsiDxe/LsiScsi.h               |  21 ++
> >  OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf          |   3 +
> >  OvmfPkg/OvmfPkg.dec                        |   3 +
> >  5 files changed, 425 insertions(+), 1 deletion(-)
> > 
> > diff --git a/OvmfPkg/Include/IndustryStandard/LsiScsi.h b/OvmfPkg/Include/IndustryStandard/LsiScsi.h
> > index 185e553c8eb4..9964bd40385c 100644
> > --- a/OvmfPkg/Include/IndustryStandard/LsiScsi.h
> > +++ b/OvmfPkg/Include/IndustryStandard/LsiScsi.h
> > @@ -26,6 +26,18 @@
> >  #define LSI_REG_SIST0             0x42
> >  #define LSI_REG_SIST1             0x43
> >  
> > +//
> > +// The status bits for DMA Status (DSTAT)
> > +//
> > +#define LSI_DSTAT_IID             BIT0
> > +#define LSI_DSTAT_R               BIT1
> > +#define LSI_DSTAT_SIR             BIT2
> > +#define LSI_DSTAT_SSI             BIT3
> > +#define LSI_DSTAT_ABRT            BIT4
> > +#define LSI_DSTAT_BF              BIT5
> > +#define LSI_DSTAT_MDPE            BIT6
> > +#define LSI_DSTAT_DFE             BIT7
> > +
> >  //
> >  // The status bits for Interrupt Status Zero (ISTAT0)
> >  //
> > @@ -38,4 +50,55 @@
> >  #define LSI_ISTAT0_SRST           BIT6
> >  #define LSI_ISTAT0_ABRT           BIT7
> >  
> > +//
> > +// The status bits for SCSI Interrupt Status Zero (SIST0)
> > +//
> > +#define LSI_SIST0_PAR             BIT0
> > +#define LSI_SIST0_RST             BIT1
> > +#define LSI_SIST0_UDC             BIT2
> > +#define LSI_SIST0_SGE             BIT3
> > +#define LSI_SIST0_RSL             BIT4
> > +#define LSI_SIST0_SEL             BIT5
> > +#define LSI_SIST0_CMP             BIT6
> > +#define LSI_SIST0_MA              BIT7
> > +
> > +//
> > +// The status bits for SCSI Interrupt Status One (SIST1)
> > +//
> > +#define LSI_SIST1_HTH             BIT0
> > +#define LSI_SIST1_GEN             BIT1
> > +#define LSI_SIST1_STO             BIT2
> > +#define LSI_SIST1_R3              BIT3
> > +#define LSI_SIST1_SBMC            BIT4
> > +#define LSI_SIST1_R5              BIT5
> > +#define LSI_SIST1_R6              BIT6
> > +#define LSI_SIST1_R7              BIT7
> > +
> > +//
> > +// LSI 53C895A Script Instructions
> > +//
> > +#define LSI_INS_TYPE_BLK          0x00000000
> > +#define LSI_INS_TYPE_IO           BIT30
> > +#define LSI_INS_TYPE_TC           BIT31
> > +
> > +#define LSI_INS_BLK_SCSIP_DAT_OUT 0x00000000
> > +#define LSI_INS_BLK_SCSIP_DAT_IN  BIT24
> > +#define LSI_INS_BLK_SCSIP_CMD     BIT25
> > +#define LSI_INS_BLK_SCSIP_STAT    (BIT24 | BIT25)
> > +#define LSI_INS_BLK_SCSIP_MSG_OUT (BIT25 | BIT26)
> > +#define LSI_INS_BLK_SCSIP_MSG_IN  (BIT24 | BIT25 | BIT26)
> > +
> > +#define LSI_INS_IO_OPC_SEL        0x00000000
> > +#define LSI_INS_IO_OPC_WAIT_RESEL BIT28
> > +
> > +#define LSI_INS_TC_CP             BIT17
> > +#define LSI_INS_TC_JMP            BIT19
> > +#define LSI_INS_TC_RA             BIT23
> > +
> > +#define LSI_INS_TC_OPC_JMP        0x00000000
> > +#define LSI_INS_TC_OPC_INT        (BIT27 | BIT28)
> > +
> > +#define LSI_INS_TC_SCSIP_DAT_OUT  0x00000000
> > +#define LSI_INS_TC_SCSIP_MSG_IN   (BIT24 | BIT25 | BIT26)
> > +
> >  #endif // _LSI_SCSI_H_
> > diff --git a/OvmfPkg/LsiScsiDxe/LsiScsi.c b/OvmfPkg/LsiScsiDxe/LsiScsi.c
> > index b3a88cc7119b..d5fe1d4ab3b8 100644
> > --- a/OvmfPkg/LsiScsiDxe/LsiScsi.c
> > +++ b/OvmfPkg/LsiScsiDxe/LsiScsi.c
> > @@ -43,6 +43,42 @@ Out8 (
> >                            );
> >  }
> >  
> > +STATIC
> > +EFI_STATUS
> > +Out32 (
> > +  IN LSI_SCSI_DEV       *Dev,
> > +  IN UINT32             Addr,
> > +  IN UINT32             Data
> > +  )
> > +{
> > +  return Dev->PciIo->Io.Write (
> > +                          Dev->PciIo,
> > +                          EfiPciIoWidthUint32,
> > +                          PCI_BAR_IDX0,
> > +                          Addr,
> > +                          1,
> > +                          &Data
> > +                          );
> > +}
> > +
> > +STATIC
> > +EFI_STATUS
> > +In8 (
> > +  IN  LSI_SCSI_DEV *Dev,
> > +  IN  UINT32       Addr,
> > +  OUT UINT8        *Data
> > +  )
> > +{
> > +  return Dev->PciIo->Io.Read (
> > +                          Dev->PciIo,
> > +                          EfiPciIoWidthUint8,
> > +                          PCI_BAR_IDX0,
> > +                          Addr,
> > +                          1,
> > +                          Data
> > +                          );
> > +}
> > +
> >  STATIC
> >  EFI_STATUS
> >  LsiScsiReset (
> > @@ -141,6 +177,303 @@ LsiScsiCheckRequest (
> >    return EFI_SUCCESS;
> >  }
> >  
> > +/**
> > +
> > +  Interpret the request packet from the Extended SCSI Pass Thru Protocol and
> > +  compose the script to submit the command and data to the controller.
> > +
> > +  @param[in] Dev          The LSI 53C895A SCSI device the packet targets.
> > +
> > +  @param[in] Target       The SCSI target controlled by the LSI 53C895A SCSI
> > +                          device.
> > +
> > +  @param[in] Lun          The Logical Unit Number under the SCSI target.
> > +
> > +  @param[in out] Packet   The Extended SCSI Pass Thru Protocol packet.
> > +
> > +
> > +  @retval EFI_SUCCESS  The Extended SCSI Pass Thru Protocol packet was valid.
> > +
> > +  @return              Otherwise, invalid or unsupported parameters were
> > +                       detected. Status codes are meant for direct forwarding
> > +                       by the EFI_EXT_SCSI_PASS_THRU_PROTOCOL.PassThru()
> > +                       implementation.
> > +
> > + **/
> > +STATIC
> > +EFI_STATUS
> > +LsiScsiProcessRequest (
> > +  IN LSI_SCSI_DEV                                   *Dev,
> > +  IN UINT8                                          Target,
> > +  IN UINT64                                         Lun,
> > +  IN OUT EFI_EXT_SCSI_PASS_THRU_SCSI_REQUEST_PACKET *Packet
> > +  )
> > +{
> > +  EFI_STATUS Status;
> > +  UINT32     *Script;
> > +  UINT8      *Cdb;
> > +  UINT8      *MsgOut;
> > +  UINT8      *MsgIn;
> > +  UINT8      *ScsiStatus;
> > +  UINT8      *Data;
> > +  UINT8      DStat;
> > +  UINT8      SIst0;
> > +  UINT8      SIst1;
> > +
> > +  Script      = Dev->Dma->Script;
> > +  Cdb         = Dev->Dma->Cdb;
> > +  Data        = Dev->Dma->Data;
> > +  MsgIn       = Dev->Dma->MsgIn;
> > +  MsgOut      = &Dev->Dma->MsgOut;
> > +  ScsiStatus  = &Dev->Dma->Status;
> > +
> > +  *ScsiStatus = 0xFF;
> > +
> > +  SetMem (Cdb, sizeof Dev->Dma->Cdb, 0x00);
> > +  CopyMem (Cdb, Packet->Cdb, Packet->CdbLength);
> > +
> > +  //
> > +  // Clean up the DMA buffer for the script.
> > +  //
> > +  SetMem (Script, sizeof Dev->Dma->Script, 0x00);
> > +
> > +  //
> > +  // Compose the script to transfer data between the host and the device.
> > +  //
> > +  // References:
> > +  //   * LSI53C895A PCI to Ultra2 SCSI Controller Version 2.2
> > +  //     - Chapter 5 SCSI SCRIPT Instruction Set
> > +  //   * SEABIOS lsi-scsi driver
> > +  //
> > +  // All instructions used here consist of 2 32bit words. The first word
> > +  // contains the command to execute. The second word is loaded into the
> > +  // DMA SCRIPTS Pointer Save (DSPS) register as either the DMA address
> > +  // for data transmission or the address/offset for the jump command.
> > +  // Some commands, such as the selection of the target, don't need to
> > +  // transfer data through DMA or jump to another instruction, then DSPS
> > +  // has to be zero.
> > +  //
> > +  // There are 3 major parts in this script. The first part (1~3) contains
> > +  // the instructions to select target and LUN and send the SCSI command
> > +  // from the request packet. The second part (4~7) is to handle the
> > +  // potential disconnection and prepare for the data transmission. The
> > +  // instructions in the third part (8~10) transmit the given data and
> > +  // collect the result. Instruction 11 raises the interrupt and marks the
> > +  // end of the script.
> > +  //
> > +
> > +  //
> > +  // 1. Select target.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_IO | LSI_INS_IO_OPC_SEL | (UINT32)Target << 16;
> > +  *Script++ = 0x00000000;
> > +
> > +  //
> > +  // 2. Select LUN.
> > +  //
> > +  *MsgOut   = 0x80 | (UINT8) Lun; // 0x80: Identify bit
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_MSG_OUT |
> > +              (UINT32)sizeof Dev->Dma->MsgOut;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, MsgOut);
> > +
> > +  //
> > +  // 3. Send the SCSI Command.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_CMD |
> > +              (UINT32)sizeof Dev->Dma->Cdb;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, Cdb);
> > +
> > +  //
> > +  // 4. Check whether the current SCSI phase is "Message In" or not
> > +  //    and jump to 7 if it is.
> > +  //    Note: LSI_INS_TC_RA stands for "Relative Address Mode", so the
> > +  //          offset 0x18 in the second word means jumping forward
> > +  //          3 (0x18/8) instructions.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_TC | LSI_INS_TC_OPC_JMP |
> > +              LSI_INS_TC_SCSIP_MSG_IN | LSI_INS_TC_RA |
> > +              LSI_INS_TC_CP;
> > +  *Script++ = 0x00000018;
> > +
> > +  //
> > +  // 5. Read "Message" from the initiator to trigger reselect.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_MSG_IN |
> > +              (UINT32)sizeof Dev->Dma->MsgIn;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, MsgIn);
> > +
> > +  //
> > +  // 6. Wait reselect.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_IO | LSI_INS_IO_OPC_WAIT_RESEL;
> > +  *Script++ = 0x00000000;
> > +
> > +  //
> > +  // 7. Read "Message" from the initiator again
> > +  //
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_MSG_IN |
> > +              (UINT32)sizeof Dev->Dma->MsgIn;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, MsgIn);
> > +
> > +  //
> > +  // 8. Set the DMA command for the read/write operations.
> > +  //    Note: Some requests, e.g. "TEST UNIT READY", do not come with
> > +  //          allocated InDataBuffer or OutDataBuffer. We skip the DMA
> > +  //          data command for those requests or this script would fail
> > +  //          with LSI_SIST0_SGE due to the zero data length.
> > +  //
> > +  // LsiScsiCheckRequest() prevents both integer overflows in the command
> > +  // opcodes, and buffer overflows.
> > +  //
> > +  if (Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_READ &&
> > +      Packet->InTransferLength > 0) {
> > +    ASSERT (Packet->InTransferLength <= sizeof Dev->Dma->Data);
> > +    *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_DAT_IN |
> > +                Packet->InTransferLength;
> > +    *Script++ = LSI_SCSI_DMA_ADDR (Dev, Data);
> > +  } else if (Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_WRITE &&
> > +             Packet->OutTransferLength > 0) {
> > +    ASSERT (Packet->OutTransferLength <= sizeof Dev->Dma->Data);
> > +    CopyMem (Data, Packet->OutDataBuffer, Packet->OutTransferLength);
> > +    *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_DAT_OUT |
> > +                Packet->OutTransferLength;
> > +    *Script++ = LSI_SCSI_DMA_ADDR (Dev, Data);
> > +  }
> 
> I understand the explanation, thanks.
> 
> However, we can still improve this code. The following sub-conditions:
> 
>   Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_READ
> 
> and
> 
>   Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_WRITE
> 
> are superfluous. What we care about are
> 
>   Packet->InTransferLength > 0
> 
> and
> 
>   Packet->OutTransferLength > 0
> 
> And the latter (length-based) conditions actually *imply* the former
> (direction-based) conditions, because:
> 
> - LsiScsiCheckRequest() returns EFI_INVALID_PARAMETER if
>   DataDirection > EFI_EXT_SCSI_DATA_DIRECTION_BIDIRECTIONAL
> 
> - LsiScsiCheckRequest() returns EFI_UNSUPPORTED if
>   DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_BIDIRECTIONAL
> 
> - LsiScsiCheckRequest() returns EFI_INVALID_PARAMETER if
>   InTransferLength > 0, but
>   DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_WRITE
> 
> - LsiScsiCheckRequest() returns EFI_INVALID_PARAMETER if
>   OutTransferLength > 0, but
>   DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_READ
> 
> This means that (InTransferLength > 0) guarantees
> EFI_EXT_SCSI_DATA_DIRECTION_READ, and (OutTransferLength > 0) guarantees
> EFI_EXT_SCSI_DATA_DIRECTION_WRITE.
> 
> (1) Therefore I suggest moving the respective sub-conditions from the
> "if" statements into the dependent blocks, as assertions:
> 
>   if (Packet->InTransferLength > 0) {
>     ASSERT (Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_READ);
>     ASSERT (Packet->InTransferLength <= sizeof Dev->Dma->Data);
>     ...
>   } else if (Packet->OutTransferLength > 0) {
>     ASSERT (Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_WRITE);
>     ASSERT (Packet->OutTransferLength <= sizeof Dev->Dma->Data);
>     ...
>   }
> 
Thanks for the suggestion. This makes the if statements easier to read.
Will modify them in v3.

> > +
> > +  //
> > +  // 9. Get the SCSI status.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_STAT |
> > +              (UINT32)sizeof Dev->Dma->Status;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, Status);
> > +
> > +  //
> > +  // 10. Get the SCSI message.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_BLK | LSI_INS_BLK_SCSIP_MSG_IN |
> > +              (UINT32)sizeof Dev->Dma->MsgIn;
> > +  *Script++ = LSI_SCSI_DMA_ADDR (Dev, MsgIn);
> > +
> > +  //
> > +  // 11. Raise the interrupt to end the script.
> > +  //
> > +  *Script++ = LSI_INS_TYPE_TC | LSI_INS_TC_OPC_INT |
> > +              LSI_INS_TC_SCSIP_DAT_OUT | LSI_INS_TC_JMP;
> > +  *Script++ = 0x00000000;
> > +
> > +  //
> > +  // Make sure the size of the script doesn't exceed the buffer.
> > +  //
> > +  ASSERT (Script <= Dev->Dma->Script + ARRAY_SIZE (Dev->Dma->Script));
> > +
> > +  //
> > +  // The controller starts to execute the script once the DMA Script
> > +  // Pointer (DSP) register is set.
> > +  //
> > +  Status = Out32 (Dev, LSI_REG_DSP, LSI_SCSI_DMA_ADDR (Dev, Script));
> > +  if (EFI_ERROR (Status)) {
> > +    goto Error;
> > +  }
> > +
> > +  //
> > +  // Poll the device registers (DSTAT, SIST0, and SIST1) until the SIR
> > +  // bit sets.
> > +  //
> > +  for(;;) {
> > +    Status = In8 (Dev, LSI_REG_DSTAT, &DStat);
> > +    if (EFI_ERROR (Status)) {
> > +      goto Error;
> > +    }
> > +    Status = In8 (Dev, LSI_REG_SIST0, &SIst0);
> > +    if (EFI_ERROR (Status)) {
> > +      goto Error;
> > +    }
> > +    Status = In8 (Dev, LSI_REG_SIST1, &SIst1);
> > +    if (EFI_ERROR (Status)) {
> > +      goto Error;
> > +    }
> > +
> > +    if (SIst0 != 0 || SIst1 != 0) {
> > +      goto Error;
> > +    }
> > +
> > +    //
> > +    // Check the SIR (SCRIPTS Interrupt Instruction Received) bit.
> > +    //
> > +    if (DStat & LSI_DSTAT_SIR) {
> > +      break;
> > +    }
> > +
> > +    gBS->Stall (Dev->StallPerPollUsec);
> > +  }
> > +
> > +  //
> > +  // Check if everything is good.
> > +  //   SCSI Message Code 0x00: COMMAND COMPLETE
> > +  //   SCSI Status  Code 0x00: Good
> > +  //
> > +  if (MsgIn[0] != 0 || *ScsiStatus != 0) {
> > +    goto Error;
> > +  }
> > +
> > +  //
> > +  // Copy Data to InDataBuffer if necessary.
> > +  //
> > +  if (Packet->DataDirection == EFI_EXT_SCSI_DATA_DIRECTION_READ) {
> > +    CopyMem (Packet->InDataBuffer, Data, Packet->InTransferLength);
> > +  }
> > +
> > +  //
> > +  // Always set SenseDataLength to 0.
> > +  // The instructions of LSI53C895A doesn't reply sense data. Instead, it
> > +  // relies on the SCSI command, "REQUEST SENSE", to get sense data. We set
> > +  // SenseDataLength to 0 to notify ScsiDiskDxe that there is no sense data
> > +  // written even if this request is processed successfully, so that It will
> > +  // issue "REQUEST SENSE" later to retrieve sense data.
> > +  //
> > +  Packet->SenseDataLength   = 0;
> > +  Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_OK;
> > +  Packet->TargetStatus      = EFI_EXT_SCSI_STATUS_TARGET_GOOD;
> > +
> > +  return EFI_SUCCESS;
> > +
> > +Error:
> > +  DEBUG ((DEBUG_VERBOSE, "%a: dstat: %02X, sist0: %02X, sist1: %02X\n",
> > +    __FUNCTION__, DStat, SIst0, SIst1));
> 
> The Error label may be reached without setting some (or even any) of
> DStat, SIst0, SIst1.
> 
> (2) Please set all three of DStat, SIst0, and SIst1 to zero, near the
> top of the function, with explicit assignments (not initialization).
> 
Right. Will set them to zero in v3.

> > +  //
> > +  // Update the request packet to reflect the status.
> > +  //
> > +  if (*ScsiStatus != 0xFF) {
> > +    Packet->TargetStatus    = *ScsiStatus;
> > +  } else {
> > +    Packet->TargetStatus    = EFI_EXT_SCSI_STATUS_TARGET_TASK_ABORTED;
> > +  }
> > +
> > +  if (SIst0 & LSI_SIST0_PAR) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_PARITY_ERROR;
> > +  } else if (SIst0 & LSI_SIST0_RST) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_BUS_RESET;
> > +  } else if (SIst0 & LSI_SIST0_UDC) {
> > +    //
> > +    // The target device is disconnected unexpectedly. According to UEFI spec,
> > +    // this is TIMEOUT_COMMAND.
> > +    //
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_TIMEOUT_COMMAND;
> > +  } else if (SIst0 & LSI_SIST0_SGE) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_DATA_OVERRUN_UNDERRUN;
> > +  } else if (SIst1 & LSI_SIST1_HTH) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_TIMEOUT;
> > +  } else if (SIst1 & LSI_SIST1_GEN) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_TIMEOUT;
> > +  } else if (SIst1 & LSI_SIST1_STO) {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_SELECTION_TIMEOUT;
> > +  } else {
> > +    Packet->HostAdapterStatus = EFI_EXT_SCSI_STATUS_HOST_ADAPTER_OTHER;
> > +  }
> 
> According to the UEFI spec, on EFI_DEVICE_ERROR (see below):
> 
>   See HostAdapterStatus, TargetStatus, SenseDataLength, and SenseData in
>   that order for additional status information.
> 
> (3) Therefore, on this error branch, please also set SenseDataLength to
> zero.
> 
Will set SenseDataLength to 0 in v3.

> > +
> > +  return EFI_DEVICE_ERROR;
> > +}
> > +
> >  //
> >  // The next seven functions implement EFI_EXT_SCSI_PASS_THRU_PROTOCOL
> >  // for the LSI 53C895A SCSI Controller. Refer to UEFI Spec 2.3.1 + Errata C,
> > @@ -168,7 +501,7 @@ LsiScsiPassThru (
> >      return Status;
> >    }
> >  
> > -  return EFI_UNSUPPORTED;
> > +  return LsiScsiProcessRequest (Dev, *Target, Lun, Packet);
> >  }
> 
> The LsiScsiPassThru() function can now return EFI_SUCCESS, without
> updating InTransferLength and OutTransferLength.
> 
> But sticking (for now) with EFI_UNSUPPORTED would also be wrong, because
> (according to the UEFI spec) EFI_UNSUPPORTED means "The SCSI Request
> Packet was not sent", and here we *did* talk to the device.
> 
> (4) So please squash the next patch -- "[PATCH v2 11/12]
> OvmfPkg/LsiScsiDxe: Calculate the transferred bytes" -- into this one,
> in the v3 series.
> 
> (The next patch, which handles the transfer lengths, is not large,
> thankfully.)
> 
Since the calculation wasn't in v1, I thought it's easier to review the
change in an extra patch :)
Will squash the patch in v3.

Gary Lin

> For now I'll comment separately under that patch.
> 
> Thanks!
> Laszlo
> 
> >  
> >  EFI_STATUS
> > @@ -474,6 +807,7 @@ LsiScsiControllerStart (
> >      );
> >    Dev->MaxTarget = PcdGet8 (PcdLsiScsiMaxTargetLimit);
> >    Dev->MaxLun = PcdGet8 (PcdLsiScsiMaxLunLimit);
> > +  Dev->StallPerPollUsec = PcdGet32 (PcdLsiScsiStallPerPollUsec);
> >  
> >    Status = gBS->OpenProtocol (
> >                    ControllerHandle,
> > diff --git a/OvmfPkg/LsiScsiDxe/LsiScsi.h b/OvmfPkg/LsiScsiDxe/LsiScsi.h
> > index 05deeed379fe..6ecf523f5a9e 100644
> > --- a/OvmfPkg/LsiScsiDxe/LsiScsi.h
> > +++ b/OvmfPkg/LsiScsiDxe/LsiScsi.h
> > @@ -13,6 +13,11 @@
> >  #define _LSI_SCSI_DXE_H_
> >  
> >  typedef struct {
> > +  //
> > +  // Allocate 32 UINT32 entries for the script and it's sufficient for
> > +  // 16 instructions.
> > +  //
> > +  UINT32                          Script[32];
> >    //
> >    // The max size of CDB is 32.
> >    //
> > @@ -25,6 +30,18 @@ typedef struct {
> >    //       Count (DBC), a 24-bit register, so the maximum is 0xFFFFFF (16MB-1).
> >    //
> >    UINT8                           Data[SIZE_64KB];
> > +  //
> > +  // For SCSI Message In phase
> > +  //
> > +  UINT8                           MsgIn[2];
> > +  //
> > +  // For SCSI Message Out phase
> > +  //
> > +  UINT8                           MsgOut;
> > +  //
> > +  // For SCSI Status phase
> > +  //
> > +  UINT8                           Status;
> >  } LSI_SCSI_DMA_BUFFER;
> >  
> >  typedef struct {
> > @@ -34,6 +51,7 @@ typedef struct {
> >    EFI_PCI_IO_PROTOCOL             *PciIo;
> >    UINT8                           MaxTarget;
> >    UINT8                           MaxLun;
> > +  UINT32                          StallPerPollUsec;
> >    LSI_SCSI_DMA_BUFFER             *Dma;
> >    EFI_PHYSICAL_ADDRESS            DmaPhysical;
> >    VOID                            *DmaMapping;
> > @@ -46,6 +64,9 @@ typedef struct {
> >  #define LSI_SCSI_FROM_PASS_THRU(PassThruPtr) \
> >    CR (PassThruPtr, LSI_SCSI_DEV, PassThru, LSI_SCSI_DEV_SIGNATURE)
> >  
> > +#define LSI_SCSI_DMA_ADDR(Dev, MemberName) \
> > +  ((UINT32)(Dev->DmaPhysical + OFFSET_OF (LSI_SCSI_DMA_BUFFER, MemberName)))
> > +
> >  
> >  //
> >  // Probe, start and stop functions of this driver, called by the DXE core for
> > diff --git a/OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf b/OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
> > index 6111449577a8..4c7abcec618f 100644
> > --- a/OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
> > +++ b/OvmfPkg/LsiScsiDxe/LsiScsiDxe.inf
> > @@ -41,3 +41,6 @@ [Protocols]
> >  [FixedPcd]
> >    gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiMaxTargetLimit   ## CONSUMES
> >    gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiMaxLunLimit      ## CONSUMES
> > +
> > +[Pcd]
> > +  gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiStallPerPollUsec ## CONSUMES
> > diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
> > index ca13a3cb11d3..f16c00ad5b99 100644
> > --- a/OvmfPkg/OvmfPkg.dec
> > +++ b/OvmfPkg/OvmfPkg.dec
> > @@ -179,6 +179,9 @@ [PcdsFixedAtBuild]
> >    gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiMaxTargetLimit|7|UINT8|0x3b
> >    gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiMaxLunLimit|0|UINT8|0x3c
> >  
> > +  ## Microseconds to stall between polling for LsiScsi request result
> > +  gUefiOvmfPkgTokenSpaceGuid.PcdLsiScsiStallPerPollUsec|5|UINT32|0x3d
> > +
> >    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageEventLogBase|0x0|UINT32|0x8
> >    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageEventLogSize|0x0|UINT32|0x9
> >    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFirmwareFdSize|0x0|UINT32|0xa
> > 
>