The "SCSI Block Commands - 2" (SBC-2) standard defines bits [7:5] of the CDB byte 1 as Reserved, for the READ and WRITE commands.
The updated "SCSI Block Commands - 3" (SBC-3) standard defines the same bitfield as RDPROTECT and WRPROTECT, respectively. After reviewing the above standards, and the following commits: - SVN r8331 (git 676e2a32), - SVN r8334 (git 6b3ecf5c), we've determined that UefiScsiLib is incorrect in encoding the LUN in this bitfield for the READ and WRITE commands. Encoding a nonzero LUN there creates unintended RDPROTECT and WRPROTECT values, which the recipient device is required to reject if it does not support protection information, with CHECK CONDITION, ILLEGAL REQUEST, INVALID FIELD IN CDB: ScsiDiskRead10: Check Condition happened! ScsiDisk: Sense Key = 0x5 ASC = 0x24! ScsiDiskRead10: Check Condition happened! ScsiDisk: Sense Key = 0x5 ASC = 0x24! ScsiDiskRead10: Check Condition happened! ScsiDisk: Sense Key = 0x5 ASC = 0x24! ScsiDiskRead10: Check Condition happened! ScsiDisk: Sense Key = 0x5 ASC = 0x24! FatOpenDevice: read of part_lba failed Device Error In practice this flaw breaks UefiScsiLib minimally on SCSI disks with nonzero LUNs that are emulated by QEMU (after QEMU commit 96bdbbab, part of v1.2.0). RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1166971 Reported-by: Cole Robinson <crobi...@redhat.com> Suggested-by: Paolo Bonzini <pbonz...@redhat.com> Suggested-by: Feng Tian <feng.t...@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <ler...@redhat.com> --- Notes: v2: - permanently remove the LUN encoding [Paolo, Feng] - https://github.com/lersek/edk2/commits/bz1166971_rdwrvr_cdb_lun_encode_v2 MdePkg/Library/UefiScsiLib/UefiScsiLib.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/MdePkg/Library/UefiScsiLib/UefiScsiLib.c b/MdePkg/Library/UefiScsiLib/UefiScsiLib.c index bd838c4..dc1847f 100644 --- a/MdePkg/Library/UefiScsiLib/UefiScsiLib.c +++ b/MdePkg/Library/UefiScsiLib/UefiScsiLib.c @@ -930,7 +930,6 @@ ScsiRead10Command ( ScsiIo->GetDeviceLocation (ScsiIo, &Target, &Lun); Cdb[0] = EFI_SCSI_OP_READ10; - Cdb[1] = (UINT8) (LShiftU64 (Lun, 5) & EFI_SCSI_LOGICAL_UNIT_NUMBER_MASK); WriteUnaligned32 ((UINT32 *)&Cdb[2], SwapBytes32 (StartLba)); WriteUnaligned16 ((UINT16 *)&Cdb[7], SwapBytes16 ((UINT16) SectorSize)); @@ -1028,7 +1027,6 @@ ScsiWrite10Command ( ScsiIo->GetDeviceLocation (ScsiIo, &Target, &Lun); Cdb[0] = EFI_SCSI_OP_WRITE10; - Cdb[1] = (UINT8) (LShiftU64 (Lun, 5) & EFI_SCSI_LOGICAL_UNIT_NUMBER_MASK); WriteUnaligned32 ((UINT32 *)&Cdb[2], SwapBytes32 (StartLba)); WriteUnaligned16 ((UINT16 *)&Cdb[7], SwapBytes16 ((UINT16) SectorSize)); @@ -1126,7 +1124,6 @@ ScsiRead16Command ( ScsiIo->GetDeviceLocation (ScsiIo, &Target, &Lun); Cdb[0] = EFI_SCSI_OP_READ16; - Cdb[1] = (UINT8) (LShiftU64 (Lun, 5) & EFI_SCSI_LOGICAL_UNIT_NUMBER_MASK); WriteUnaligned64 ((UINT64 *)&Cdb[2], SwapBytes64 (StartLba)); WriteUnaligned32 ((UINT32 *)&Cdb[10], SwapBytes32 (SectorSize)); @@ -1224,7 +1221,6 @@ ScsiWrite16Command ( ScsiIo->GetDeviceLocation (ScsiIo, &Target, &Lun); Cdb[0] = EFI_SCSI_OP_WRITE16; - Cdb[1] = (UINT8) (LShiftU64 (Lun, 5) & EFI_SCSI_LOGICAL_UNIT_NUMBER_MASK); WriteUnaligned64 ((UINT64 *)&Cdb[2], SwapBytes64 (StartLba)); WriteUnaligned32 ((UINT32 *)&Cdb[10], SwapBytes32 (SectorSize)); -- 1.8.3.1 ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk _______________________________________________ edk2-devel mailing list edk2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/edk2-devel
