[RFCv2 0/7] vhost/scsi: Add T10 PI SGL passthrough support

["Nicholas A. Bellinger" <nab@daterainc.com>]

From: Nicholas Bellinger <nab@linux-iscsi.org>

Hi MST, MKP, Paolo & Co,

This is an updated -v2 series for adding T1O protection information (PI)
SGL passthrough support between virtio-scsi LLD + vhost-scsi fabric
endpoints.

The patch series is available at:

  git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending.git vhost-dif

Following Paolo's recommendations, this patch adds a new virtio_scsi command
header (virtio_scsi_cmd_req_pi) with the following elements to signal the
existence of protection information:

     ->do_pi_niov (DataOUT PI number of iovecs)
     ->di_pi_noiv (DataIN PI number of iovecs)

Also included is the change to attach protection information preceeding the
actual DataOUT + DataIN data payload, thus making a future improvement of
processing virtio buffers inline a possibility.

vhost-scsi code has also been updated to determine virtio_scsi_cmd_req or
virtio_scsi_cmd_req_pi usage based upon the first iovec's (header) length,
and then continues to process in either mode accordingly.

As with the original RFC, the virtio-scsi patch still contains a hack
to force DIX/DIF to be enabled, regardless of host provided feature bits.
This regression bug still needs to be tracked down.

v2 changes:
  - Add virtio_scsi_cmd_req_pi header (Paolo + nab)
  - Use virtio_scsi_cmd_req_pi instead of existing ->prio (Paolo + nab)
  - Make protection buffer come before data buffer (Paolo + nab)
  - Update vhost_scsi_get_tag() parameter usage (nab)

Please review.

Thanks!

--nab

Nicholas Bellinger (7):
  virtio-scsi.h: Add virtio_scsi_cmd_req_pi header definition
  vhost/scsi: Move sanity check into vhost_scsi_map_iov_to_sgl
  vhost/scsi: Add preallocation of protection SGLs
  vhost/scsi: Add T10 PI IOV -> SGL memory mapping logic
  vhost/scsi: Enable T10 PI IOV -> SGL memory mapping
  vhost/scsi: Add new VIRTIO_SCSI_F_T10_PI feature bit
  virtio-scsi: Enable DIF/DIX modes in SCSI host LLD

 drivers/scsi/virtio_scsi.c  |   79 +++++++++---
 drivers/vhost/scsi.c        |  289 +++++++++++++++++++++++++++++--------------
 include/linux/virtio_scsi.h |   15 ++-
 3 files changed, 273 insertions(+), 110 deletions(-)

-- 
1.7.2.5