Re: [Qemu-devel] [PATCH for-2.2 0/5] scsi: enable passthrough of vendor-specific commands

[TAMUKI Shoichi]

Hello,

From: Paolo Bonzini <address@hidden>
Subject: [PATCH for-2.2 0/5] scsi: enable passthrough of vendor-specific 
commands
Date: Wed, 16 Jul 2014 14:54:45 +0200

> Right now scsi-generic is parsing the CDB, in order to compute
> the expected number of bytes to be transferred.  This is necessary
> if DMA is done by the HBA via scsi_req_data, but it prevents executing
> vendor-specific commands via scsi-generic because we don't know how
> to parse them.
> 
> If DMA is delegated to the SCSI layer via get_sg_list, we know in
> advance how many bytes the guest will want to receive and we can pass
> the information straight from the guest to SG_IO.  In this case, it is
> unnecessary to parse the CDB to get the same information.  scsi-disk needs
> it to detect underruns and overruns, but scsi-generic and scsi-block can
> just ask the HBA about the transfer direction and size.
> 
> This series introduces a new parse_cdb callback in both the device and
> the HBA.  The latter is called by scsi_bus_parse_cdb, which devices can
> call for passthrough requests in their implementation of parse_cdb.

Great, thanks a lot.

> Tamuki-san, can you please test if these patches are okay for your
> usecase?

I tested these patches against 5a73480 (Update version for v2.1.0-rc2
release,) and confirmed that a vendor-specific command sent from the
initiator in a guest successfully reach (at least) the host using
sg_raw and ftrace.  That works fine.

Regards,
TAMUKI Shoichi