> -----Original Message----- > From: Stephen Hemminger [mailto:stephen@xxxxxxxxxxxxxxxxxx] > Sent: Tuesday, March 7, 2017 9:16 AM > To: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang > <haiyangz@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>; > martin.petersen@xxxxxxxxxx; hch@xxxxxx; hare@xxxxxxx > Cc: linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxxxxxxxxxxxxxx; Stephen Hemminger > <sthemmin@xxxxxxxxxxxxx> > Subject: [PATCH] storvsc: workaround for virtual DVD SCSI version > > Hyper-V host emulation of SCSI for virtual DVD device reports SCSI > version 0 (UNKNOWN) but is still capable of supporting REPORTLUN. > > Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11 > successfully with virtual DVD ROM device. What happens is that the > SCSI scan process falls back to doing sequential probing by INQUIRY. > But the storvsc driver has a previous workaround that masks/blocks all > errors reports from INQUIRY (or MODE_SENSE) commands. This workaround > causes the scan to then populate a full set of bogus LUN's on the > target and then sends kernel spinning off into a death spiral doing > block reads on the non-existent LUNs. > > By setting the correct blacklist flags, the target with the > DVD device is scanned with REPORTLUN and that works correctly. > > Patch needs to go in current 4.11, it is safe but not necessary > in older kernels. > > Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > --- > drivers/scsi/storvsc_drv.c | 27 +++++++++++++++++---------- > 1 file changed, 17 insertions(+), 10 deletions(-) > > PS: The error handling does need to be fixed (have patches pending) > but that is interrelated with hotplug and can wait. > > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c > index 638e5f427c90..19973e874830 100644 > --- a/drivers/scsi/storvsc_drv.c > +++ b/drivers/scsi/storvsc_drv.c > @@ -400,8 +400,6 @@ > MODULE_PARM_DESC(storvsc_vcpus_per_sub_channel, "Ratio of VCPUs to > subchannels") > */ > static int storvsc_timeout = 180; > > -static int msft_blist_flags = BLIST_TRY_VPD_PAGES; > - > #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS) > static struct scsi_transport_template *fc_transport_template; > #endif > @@ -1383,6 +1381,22 @@ static int storvsc_do_io(struct hv_device *device, > return ret; > } > > +static int storvsc_device_alloc(struct scsi_device *sdevice) > +{ > + /* > + * Set blist flag to permit the reading of the VPD pages even when > + * the target may claim SPC-2 compliance. MSFT targets currently > + * claim SPC-2 compliance while they implement post SPC-2 features. > + * With this flag we can correctly handle WRITE_SAME_16 issues. > + * > + * Hypervisor reports SCSI_UNKNOWN type for DVD ROM device but > + * still supports REPORT LUN. > + */ > + sdevice->sdev_bflags = BLIST_REPORTLUN2 | > BLIST_TRY_VPD_PAGES; > + > + return 0; > +} > + > static int storvsc_device_configure(struct scsi_device *sdevice) > { > > @@ -1396,14 +1410,6 @@ static int storvsc_device_configure(struct > scsi_device *sdevice) > sdevice->no_write_same = 1; > > /* > - * Add blist flags to permit the reading of the VPD pages even when > - * the target may claim SPC-2 compliance. MSFT targets currently > - * claim SPC-2 compliance while they implement post SPC-2 features. > - * With this patch we can correctly handle WRITE_SAME_16 issues. > - */ > - sdevice->sdev_bflags |= msft_blist_flags; > - > - /* > * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3 > * if the device is a MSFT virtual device. If the host is > * WIN10 or newer, allow write_same. > @@ -1661,6 +1667,7 @@ static struct scsi_host_template scsi_driver = { > .eh_host_reset_handler = storvsc_host_reset_handler, > .proc_name = "storvsc_host", > .eh_timed_out = storvsc_eh_timed_out, > + .slave_alloc = storvsc_device_alloc, > .slave_configure = storvsc_device_configure, > .cmd_per_lun = 255, > .this_id = -1, > -- > 2.11.0
