On Tue, 03/27 18:14, Daniel Henrique Barboza wrote: > QEMU SCSI code makes assumptions about how the PROTECT and BYTCHK > works in the protocol, denying support for PI (Protection > Information) in case the guest OS requests it. However, in SCSI versions 2 > and older, there is no PI concept in the protocol. > > This means that when dealing with such devices: > > - there is no PROTECT bit in byte 5 of the standard INQUIRY response. The > whole byte is marked as "Reserved"; > > - there is no RDPROTECT in byte 2 of READ. We have 'Logical Unit Number' > in this field instead; > > - there is no VRPROTECT in byte 2 of VERIFY. We have 'Logical Unit Number' > in this field instead. This also means that the BYTCHK bit in this case > is not related to PI. > > Since QEMU does not consider these changes, a SCSI passthrough using > a SCSI-2 device will not work. It will mistake these fields with > PI information and return Illegal Request SCSI SENSE thinking > that the driver is asking for PI support. > > This patch fixes it by adding a new attribute called 'scsi_version' > that is read from the standard INQUIRY response of passthrough > devices. This allows for a version verification before applying > conditions related to PI that doesn't apply for older versions. > > Reported-by: Dac Nguyen <da...@us.ibm.com> > Signed-off-by: Daniel Henrique Barboza <danie...@linux.vnet.ibm.com> > --- > > Changes in v3: > - moved the scsi_version initialization from realize functions to > reset functions, allowing the scsi_version to be redefined again after > each reboot.
Reviewed-by: Fam Zheng <f...@redhat.com>
