Xen devel - Jan 2011 - [RFC PATCH v01] Xen PVSCSI drivers for pvops xen/stable-2.6.32.x kernel

Hello,

http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff

This is the first version of Xen PVSCSI drivers, both the scsiback backend and
scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux kernel to 
pvops xen/stable-2.6.32.x branch.

At the moment it''s *only* compile-tested with the latest
xen/stable-2.6.32.x
git kernel as of today (2.6.32.27), on Fedora 14 x86_64.

Comments welcome.

I''m sure there are still things to fix in it. 
Hopefully I managed to properly fix all the differences between Xenlinux
<-> pvops..
Let me know how it goes, if you feel adventurous enough to try it :)

More info: http://wiki.xensource.com/xenwiki/XenPVSCSI

-- Pasi



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On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@iki.fi>
wrote:
> Hello,
>
>
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
>
> This is the first version of Xen PVSCSI drivers, both the scsiback backend
and
> scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux kernel to
> pvops xen/stable-2.6.32.x branch.
>
> -- Pasi
That''s great. Some comments based on my experience with pvusb:

1) You''ve added GNTST_eagain into include/xen/interface/grant_table.h.
When porting the pvusb drivers I removed the "check and retry" loops
based on GNTST_eagain because I noticed that netback and blkback don''t
do that. Looking at the grant_table code in xen-4.0-testing I don''t
think GNTST_eagain is used now. Perhaps someone with knowledge of the
history of GNTST_eagain could help to clarify.

2) When porting pvusb I found I had to take care with the
gnttab_grant_foreign_access_ref calls. Following the example of
blkback I replaced
   buffer_pfn = page_to_phys(page) >> PAGE_SHIFT;
with
   buffer_mfn = pfn_to_mfn(page_to_pfn(page));
The situation for pvscsi looks a bit more involved (e.g. buffer_pfn++).

3) The existing xen-netfront, xen-blkfront and xen-pcifront have been
converted to a single .c module when ported to pvops. I followed that
lead with pvusb. You might like to do the same for consistency.

Nathanael

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On Thu, 2011-01-06 at 22:31 +0000, Pasi Kärkkäinen
wrote:
> Hello,
> 
>
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> 
> This is the first version of Xen PVSCSI drivers, both the scsiback backend
and
> scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux kernel to 
> pvops xen/stable-2.6.32.x branch.
> 
> At the moment it''s *only* compile-tested with the latest
xen/stable-2.6.32.x
> git kernel as of today (2.6.32.27), on Fedora 14 x86_64.
> 
> Comments welcome.
Without wanting to sound like a broken record:

<insert same comments regarding maintainership and upstreaming as the
recent pvusb thread ;-)>
> 
> I''m sure there are still things to fix in it. 
> Hopefully I managed to properly fix all the differences between Xenlinux
<-> pvops..
> Let me know how it goes, if you feel adventurous enough to try it :)
> 
> More info: http://wiki.xensource.com/xenwiki/XenPVSCSI
> 
> -- Pasi
> 


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On Fri, 2011-01-07 at 10:03 +0000, Nathanael Rensen
wrote:
> On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > Hello,
> >
> >
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> >
> > This is the first version of Xen PVSCSI drivers, both the scsiback
backend and
> > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux
kernel to
> > pvops xen/stable-2.6.32.x branch.
> >
> > -- Pasi
> 
> That''s great. Some comments based on my experience with pvusb:
> 
> 1) You''ve added GNTST_eagain into
include/xen/interface/grant_table.h.
> When porting the pvusb drivers I removed the "check and retry"
loops
> based on GNTST_eagain because I noticed that netback and blkback
don''t
> do that. Looking at the grant_table code in xen-4.0-testing I
don''t
> think GNTST_eagain is used now. Perhaps someone with knowledge of the
> history of GNTST_eagain could help to clarify.
IIRC GNTST_eagain was added to the classic Xen trees but never forward
ported to pvops.

It''s part of the page sharing paging work (so dom0 can deal with a
paged/shared guest rather than for paging of dom0 itself). I guess those
don''t work with pvops kernels? CC''ing the guys who are working
on that
stuff.

(The presence of the use of msleep in the eagain case is a bit
terrifying. Stripping it out for now and redoing it might not be a bad
plan)

Ian.


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On Fri, Jan 07, 2011 at 10:10:20AM +0000, Ian Campbell
wrote:
> On Thu, 2011-01-06 at 22:31 +0000, Pasi Kärkkäinen wrote:
> > Hello,
> > 
> >
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> > 
> > This is the first version of Xen PVSCSI drivers, both the scsiback
backend and
> > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux
kernel to
> > pvops xen/stable-2.6.32.x branch.
> > 
> > At the moment it''s *only* compile-tested with the latest
xen/stable-2.6.32.x
> > git kernel as of today (2.6.32.27), on Fedora 14 x86_64.
> > 
> > Comments welcome.
> 
> Without wanting to sound like a broken record:
> 
> <insert same comments regarding maintainership and upstreaming as the
> recent pvusb thread ;-)>
> 
Yeah I knew this comment was coming up, so maybe I should have
mentioned already earlier that I''m aware :)

This patch needs testing and cleaning up, and obviously upstreaming..
We''ll get there :)

-- Pasi


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On Fri, Jan 07, 2011 at 10:26:56AM +0000, Ian Campbell
wrote:
> On Fri, 2011-01-07 at 10:03 +0000, Nathanael Rensen wrote:
> > On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > > Hello,
> > >
> > >
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> > >
> > > This is the first version of Xen PVSCSI drivers, both the
scsiback backend and
> > > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux
kernel to
> > > pvops xen/stable-2.6.32.x branch.
> > >
> > > -- Pasi
> > 
> > That''s great. Some comments based on my experience with
pvusb:
> > 
> > 1) You''ve added GNTST_eagain into
include/xen/interface/grant_table.h.
> > When porting the pvusb drivers I removed the "check and
retry" loops
> > based on GNTST_eagain because I noticed that netback and blkback
don''t
> > do that. Looking at the grant_table code in xen-4.0-testing I
don''t
> > think GNTST_eagain is used now. Perhaps someone with knowledge of the
> > history of GNTST_eagain could help to clarify.
> 
> IIRC GNTST_eagain was added to the classic Xen trees but never forward
> ported to pvops.
> 
Yeah, I noticed GNTST_eagain was missing from pvops, so I just blindly 
copied it from Xenlinux to pvops.. 

With the first version of PVSCSI for pvops I tried to do minimal
changes, just enough to make it compile.. 

So that stuff needs some more attention.
> It''s part of the page sharing paging work (so dom0 can deal with a
> paged/shared guest rather than for paging of dom0 itself). I guess those
> don''t work with pvops kernels? CC''ing the guys who are
working on that
> stuff.
> 
> (The presence of the use of msleep in the eagain case is a bit
> terrifying. Stripping it out for now and redoing it might not be a bad
> plan)
> 
-- Pasi


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On Fri, Jan 07, 2011 at 06:03:59PM +0800, Nathanael Rensen
wrote:
> On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > Hello,
> >
> >
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> >
> > This is the first version of Xen PVSCSI drivers, both the scsiback
backend and
> > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux
kernel to
> > pvops xen/stable-2.6.32.x branch.
> >
> > -- Pasi
> 
> That''s great. Some comments based on my experience with pvusb:
> 
> 1) You''ve added GNTST_eagain into
include/xen/interface/grant_table.h.
> When porting the pvusb drivers I removed the "check and retry"
loops
> based on GNTST_eagain because I noticed that netback and blkback
don''t
> do that. Looking at the grant_table code in xen-4.0-testing I
don''t
> think GNTST_eagain is used now. Perhaps someone with knowledge of the
> history of GNTST_eagain could help to clarify.
> 
Yep, I commented about this on the other email.
> 2) When porting pvusb I found I had to take care with the
> gnttab_grant_foreign_access_ref calls. Following the example of
> blkback I replaced
>    buffer_pfn = page_to_phys(page) >> PAGE_SHIFT;
> with
>    buffer_mfn = pfn_to_mfn(page_to_pfn(page));
> The situation for pvscsi looks a bit more involved (e.g. buffer_pfn++).
> 
Yeah, I had to hack that stuff aswell.. I was pretty tired so not sure
at all I did it correctly :)

I''ll get back to it some day now and take another look at it.
And actually do some *testing* with the patch :)
> 3) The existing xen-netfront, xen-blkfront and xen-pcifront have been
> converted to a single .c module when ported to pvops. I followed that
> lead with pvusb. You might like to do the same for consistency.
> 
Yep, I noticed this aswell. The first version was meant to be
"minimal changes just to make it compile". I need to do this change
aswell.

Thanks for the comments! 

-- Pasi


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> Yep, I noticed this aswell. The first version was meant to be
> "minimal changes just to make it compile". I need to do this
change aswell.
I like the idea of keeping the authorship, and the subsequent patches in sync.
If you can please CC me on the patches and I can track them in my git tree.

Should I use the patch you posted or wait a bit?

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On Fri, Jan 07, 2011 at 11:50:26AM -0500, Konrad Rzeszutek Wilk
wrote:
> > Yep, I noticed this aswell. The first version was meant to be
> > "minimal changes just to make it compile". I need to do this
change aswell.
> 
> I like the idea of keeping the authorship, and the subsequent patches in
sync.
> If you can please CC me on the patches and I can track them in my git tree.
> 
Ok.
> Should I use the patch you posted or wait a bit?
>
I think you should wait a bit.. I''ll take another look at it,
and post second version.

-- Pasi


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On Fri, Jan 07, Ian Campbell wrote:
> On Fri, 2011-01-07 at 10:03 +0000, Nathanael Rensen wrote:
> > On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@iki.fi> wrote:
> > > Hello,
> > >
> > >
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> > >
> > > This is the first version of Xen PVSCSI drivers, both the
scsiback backend and
> > > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux
kernel to
> > > pvops xen/stable-2.6.32.x branch.
> > >
> > > -- Pasi
> > 
> > That''s great. Some comments based on my experience with
pvusb:
> > 
> > 1) You''ve added GNTST_eagain into
include/xen/interface/grant_table.h.
> > When porting the pvusb drivers I removed the "check and
retry" loops
> > based on GNTST_eagain because I noticed that netback and blkback
don''t
> > do that. Looking at the grant_table code in xen-4.0-testing I
don''t
> > think GNTST_eagain is used now. Perhaps someone with knowledge of the
> > history of GNTST_eagain could help to clarify.
> 
> IIRC GNTST_eagain was added to the classic Xen trees but never forward
> ported to pvops.
> 
> It''s part of the page sharing paging work (so dom0 can deal with a
> paged/shared guest rather than for paging of dom0 itself). I guess those
> don''t work with pvops kernels? CC''ing the guys who are
working on that
> stuff.
I have not tried the pvops kernel with xenpaging.
> (The presence of the use of msleep in the eagain case is a bit
> terrifying. Stripping it out for now and redoing it might not be a bad
> plan)
Right now the retry is required for xenpaging, otherwise the guests
filesystem will be corrupted.
In the long run the newly added waitqueue feature may be used to make
the page access transparent to the guest and dom0.


Olaf


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On Mon, 2011-01-10 at 10:15 +0000, Olaf Hering wrote:
> 
> > (The presence of the use of msleep in the eagain case is a bit
> > terrifying. Stripping it out for now and redoing it might not be a
> bad
> > plan)
> 
> Right now the retry is required for xenpaging, otherwise the guests
> filesystem will be corrupted.
> In the long run the newly added waitqueue feature may be used to make
> the page access transparent to the guest and dom0.
I mistakenly thought msleep was a spinning type wait, but it does
actually sleep properly so it''s probably not as bad as I thought.

Ian.


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On Fri, Jan 07, 2011 at 12:31:21AM +0200, Pasi Kärkkäinen
wrote:
> Hello,
> 
>
http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-2.6.32.27-pvops-v01.diff
> 
> This is the first version of Xen PVSCSI drivers, both the scsiback backend
and
> scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux kernel to 
> pvops xen/stable-2.6.32.x branch.
> 
> At the moment it''s *only* compile-tested with the latest
xen/stable-2.6.32.x
> git kernel as of today (2.6.32.27), on Fedora 14 x86_64.
> 
> Comments welcome.
> 
> I''m sure there are still things to fix in it. 
> Hopefully I managed to properly fix all the differences between Xenlinux
<-> pvops..
> Let me know how it goes, if you feel adventurous enough to try it :)
I took a look at the patches and rebased them on top of v3.0 some time ago.

Had to fix up some things, but not much (most of the P2M API calls, and some of
the
grant table modifications) and stuck the patches in:

git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git devel/xen-scsi.v1.0

Attached is also the full patch against v3.0 kernel. I found that it works
with my SCSI disks, but you need to use Xen 4.1 (and xm). Earlier versions
do something weird. I am not really sure who is using it 

Ah, I also put the 2Tb fix in it.

 drivers/scsi/Kconfig                   |   16 +
 drivers/scsi/Makefile                  |    2 +
 drivers/scsi/xen-scsiback/Makefile     |    4 +
 drivers/scsi/xen-scsiback/common.h     |  187 ++++++++
 drivers/scsi/xen-scsiback/emulate.c    |  478 ++++++++++++++++++++
 drivers/scsi/xen-scsiback/interface.c  |  141 ++++++
 drivers/scsi/xen-scsiback/scsiback.c   |  757 ++++++++++++++++++++++++++++++++
 drivers/scsi/xen-scsiback/translate.c  |  168 +++++++
 drivers/scsi/xen-scsiback/xenbus.c     |  374 ++++++++++++++++
 drivers/scsi/xen-scsifront/Makefile    |    4 +
 drivers/scsi/xen-scsifront/common.h    |  137 ++++++
 drivers/scsi/xen-scsifront/scsifront.c |  469 ++++++++++++++++++++
 drivers/scsi/xen-scsifront/xenbus.c    |  414 +++++++++++++++++
 include/xen/interface/grant_table.h    |    4 +
 include/xen/interface/io/vscsiif.h     |  105 +++++
 15 files changed, 3260 insertions(+), 0 deletions(-)


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