Linux Virtualization - Apr 2014 - [PATCH 6/6] virtio-scsi: Enable DIF/DIX modes in SCSI host LLD

On Mon, Apr 07, 2014 at 01:56:59AM -0700, Nicholas A. Bellinger
wrote:
> On Mon, 2014-04-07 at 11:45 +0300, Michael S. Tsirkin wrote:
> > On Sun, Apr 06, 2014 at 09:32:09PM +0000, Nicholas A. Bellinger wrote:
> > > From: Nicholas Bellinger <nab at linux-iscsi.org>
> > > 
> > > This patch updates virtscsi_probe() to setup necessary Scsi_Host
> > > level protection resources. (currently hardcoded to 1)
> > > 
> > > It changes virtscsi_add_cmd() to attach outgoing / incoming
> > > protection SGLs preceeding the data payload, and is using the
> > > new virtio_scsi_cmd_req_pi->d[oi],pi_niv field to signal
> > > to signal to vhost/scsi how many prot_sgs to expect.
> > > 
> > > v3 changes:
> > >   - Use VIRTIO_SCSI_F_T10_PI to determine PI or non PI header
(Paolo)
> > > 
> > > v2 changes:
> > >   - Make protection buffer come before data buffer (Paolo)
> > >   - Enable virtio_scsi_cmd_req_pi usage (Paolo)
> > > 
> > > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > > Cc: Michael S. Tsirkin <mst at redhat.com>
> > > Cc: Martin K. Petersen <martin.petersen at oracle.com>
> > > Cc: Christoph Hellwig <hch at lst.de>
> > > Cc: Hannes Reinecke <hare at suse.de>
> > > Cc: Sagi Grimberg <sagig at dev.mellanox.co.il>
> > > Cc: H. Peter Anvin <hpa at zytor.com>
> > > Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
> > 
> > OK but we need to document the new interface in the spec
> > (and incidentially, this will be useful to verify the assumptions
> > made here and on the host side).
> > Could you please submit this proposal to the OASIS Virtio TC
> > for inclusion into the next spec draft?
> > Ideally as a patch against the tex source, but a prose
> > description would do as well.
> 
> Most certainly.  Please give me a bit to follow up on this, as the next
> couple of days are going to be hellishly busy..
> 
> > The TC meets on a bi-weekly basis, we should be able to ratify
> > this quickly.
> > 
> 
> Aside from that, please consider ACK'ing the vhost specific changes so
> these can make it into v3.15-rc1 code.
> 
> --nab
> 
Hmm but what if the TC wants to change the interface somewhat?
I guess we'll still be able to fix it after the merge window -
(or worst case, revert the change) is this what you are suggesting?

-- 
MST

On Mon, 2014-04-07 at 12:02 +0300, Michael S. Tsirkin
wrote:
> On Mon, Apr 07, 2014 at 01:56:59AM -0700, Nicholas A. Bellinger wrote:
> > On Mon, 2014-04-07 at 11:45 +0300, Michael S. Tsirkin wrote:
> > > On Sun, Apr 06, 2014 at 09:32:09PM +0000, Nicholas A. Bellinger
wrote:
> > > > From: Nicholas Bellinger <nab at linux-iscsi.org>
> > > > 
> > > > This patch updates virtscsi_probe() to setup necessary
Scsi_Host
> > > > level protection resources. (currently hardcoded to 1)
> > > > 
> > > > It changes virtscsi_add_cmd() to attach outgoing / incoming
> > > > protection SGLs preceeding the data payload, and is using
the
> > > > new virtio_scsi_cmd_req_pi->d[oi],pi_niv field to signal
> > > > to signal to vhost/scsi how many prot_sgs to expect.
> > > > 
> > > > v3 changes:
> > > >   - Use VIRTIO_SCSI_F_T10_PI to determine PI or non PI
header (Paolo)
> > > > 
> > > > v2 changes:
> > > >   - Make protection buffer come before data buffer (Paolo)
> > > >   - Enable virtio_scsi_cmd_req_pi usage (Paolo)
> > > > 
> > > > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > > > Cc: Michael S. Tsirkin <mst at redhat.com>
> > > > Cc: Martin K. Petersen <martin.petersen at oracle.com>
> > > > Cc: Christoph Hellwig <hch at lst.de>
> > > > Cc: Hannes Reinecke <hare at suse.de>
> > > > Cc: Sagi Grimberg <sagig at dev.mellanox.co.il>
> > > > Cc: H. Peter Anvin <hpa at zytor.com>
> > > > Signed-off-by: Nicholas Bellinger <nab at
linux-iscsi.org>
> > > 
> > > OK but we need to document the new interface in the spec
> > > (and incidentially, this will be useful to verify the assumptions
> > > made here and on the host side).
> > > Could you please submit this proposal to the OASIS Virtio TC
> > > for inclusion into the next spec draft?
> > > Ideally as a patch against the tex source, but a prose
> > > description would do as well.
> > 
> > Most certainly.  Please give me a bit to follow up on this, as the
next
> > couple of days are going to be hellishly busy..
> > 
> > > The TC meets on a bi-weekly basis, we should be able to ratify
> > > this quickly.
> > > 
> > 
> > Aside from that, please consider ACK'ing the vhost specific
changes so
> > these can make it into v3.15-rc1 code.
> > 
> > --nab
> > 
> 
> Hmm but what if the TC wants to change the interface somewhat?
I don't have a objection to changing the interface post-merge.
> I guess we'll still be able to fix it after the merge window -
> (or worst case, revert the change) is this what you are suggesting?
> 
Yes, but I would think that it is actually fixable.  ;)

Otherwise, a v3.16 merge is an option as well.  It's really your +
Paolo's call here. 

--nab

Il 07/04/2014 05:13, Nicholas A. Bellinger ha scritto:
>> > I guess we'll still be able to fix it after the merge window -
>> > (or worst case, revert the change) is this what you are
suggesting?
>> >
> Yes, but I would think that it is actually fixable.  ;)
>
> Otherwise, a v3.16 merge is an option as well.  It's really your +
> Paolo's call here.
With s/niov/nbytes/, I think the interface is fine.  If you can do it 
this week, it is your call as target maintainer...

I don't have to do much more than give my acked-by for the changes to 
the virtio-scsi drivers, it's up to you whether to use it for 3.15 or 3.16.

Paolo