[Qemu-devel] [PATCH 00/16] Megasas HBA emulation and SCSI update

[Hannes Reinecke]

Due to popular demand here is now the LSI Megaraid HBA emulation.
And an update to the SCSI stack to bring it more in line with
modern standards.

For the SCSI update there are three key points:
- Improved sense code handling: the SCSI standard specifies several
  sense codes to be returned on common errors; we should be following
  that.
- Reworked SCSI layer: Instead of indirectly addressing a SCSI
  request by an abstract 'tag' we're now using the request directly,
  thus saving us a lookup on every invocation.
- Add iovec passing: I've added an interface to pass an iovec
  to a SCSI request, so that we don't need to use bounce buffers
  for data transfer. The old interface is left in place.

And, of course, the megasas driver itself.

A quick 'dd' comparison against virtio on a tmpfs backed sparse file shows:

# dd if=/dev/sdb of=/dev/null bs=16M count=1000 iflag=direct
1000+0 records in
1000+0 records out
16777216000 bytes (17 GB) copied, 9.40123 s, 1.8 GB/s
# dd if=/dev/vda of=/dev/null bs=16M count=1000 iflag=direct
1000+0 records in
1000+0 records out
16777216000 bytes (17 GB) copied, 7.44681 s, 2.3 GB/s

So we're having about 80% virtio speed.
Unoptimized :-)

And the patches in detail:

Hannes Reinecke (16):
  Allow zero alloc_hint in qemu_sglist_init()
  scsi: Increase the number of possible devices
  scsi: Return SAM status codes
  scsi: INQUIRY VPD fixes
  scsi: Move sense handling into the driver
  scsi-disk: Remove duplicate cdb parsing
  scsi: Update sense code handling
  lsi53c895a: Rename 'sense' to 'status'
  scsi-disk: Allocate iovec dynamically
  scsi: Use 'SCSIRequest' directly
  scsi-disk: add data direction checking
  scsi-generic: use plain ioctl
  Remove 'bus' argument from SCSI command completion callbacks
  scsi: Implement 'get_sense' callback
  scsi: Implement get_req_iov callback
  megasas: LSI Megaraid SAS emulation

 Makefile.objs     |    2 +-
 blockdev.h        |    2 +-
 dma-helpers.c     |    5 +-
 hw/esp.c          |   23 +-
 hw/lsi53c895a.c   |   46 +-
 hw/megasas.c      | 1826 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/mfi.h          | 1197 +++++++++++++++++++++++++++++++++++
 hw/pci_ids.h      |    2 +
 hw/scsi-bus.c     |  120 +++-
 hw/scsi-defs.h    |   20 +-
 hw/scsi-disk.c    |  456 +++++++-------
 hw/scsi-generic.c |  249 ++++----
 hw/scsi.h         |   64 ++-
 hw/usb-msd.c      |   26 +-
 14 files changed, 3599 insertions(+), 439 deletions(-)
 create mode 100644 hw/megasas.c
 create mode 100644 hw/mfi.h