4.9-stable review patch. If anyone has any objections, please let me know.
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From: David Gibson david@gibson.dropbear.id.au
[ Upstream commit 25d1d50e23275e141e3a3fe06c25a99f4c4bf4e0 ]
Passed through SCSI targets may have transfer limits which come from the host SCSI controller or something on the host side other than the target itself.
To make this work properly, the hypervisor can adjust the target's VPD information to advertise these limits. But for that to work, the guest has to look at the VPD pages, which we won't do by default if it is an SPC-2 device, even if it does actually support it.
This adds a workaround to address this, forcing devices attached to a virtio-scsi controller to always check the VPD pages. This is modelled on a similar workaround for the storvsc (Hyper-V) SCSI controller, although that exists for slightly different reasons.
A specific case which causes this is a volume from IBM's IPR RAID controller (which presents as an SPC-2 device, although it does support VPD) passed through with qemu's 'scsi-block' device.
[mkp: fixed typo]
Signed-off-by: David Gibson david@gibson.dropbear.id.au Acked-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/virtio_scsi.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
--- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -28,6 +28,7 @@ #include <scsi/scsi_device.h> #include <scsi/scsi_cmnd.h> #include <scsi/scsi_tcq.h> +#include <scsi/scsi_devinfo.h> #include <linux/seqlock.h>
#define VIRTIO_SCSI_MEMPOOL_SZ 64 @@ -705,6 +706,28 @@ static int virtscsi_device_reset(struct return virtscsi_tmf(vscsi, cmd); }
+static int virtscsi_device_alloc(struct scsi_device *sdevice) +{ + /* + * Passed through SCSI targets (e.g. with qemu's 'scsi-block') + * may have transfer limits which come from the host SCSI + * controller or something on the host side other than the + * target itself. + * + * To make this work properly, the hypervisor can adjust the + * target's VPD information to advertise these limits. But + * for that to work, the guest has to look at the VPD pages, + * which we won't do by default if it is an SPC-2 device, even + * if it does actually support it. + * + * So, set the blist to always try to read the VPD pages. + */ + sdevice->sdev_bflags = BLIST_TRY_VPD_PAGES; + + return 0; +} + + /** * virtscsi_change_queue_depth() - Change a virtscsi target's queue depth * @sdev: Virtscsi target whose queue depth to change @@ -776,6 +799,7 @@ static struct scsi_host_template virtscs .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, + .slave_alloc = virtscsi_device_alloc,
.can_queue = 1024, .dma_boundary = UINT_MAX,