RE: [Xen-devel] GNTTAB_copy

["Kumar, Venkat" <Venkat.Kumar@xxxxxxx>]

Steve,

Atlast it worked out. I had to make some changes in Xen (it wasn't allowing a 
copy across domains) to make it work apart from the patch you sent.

Thx,
Venkat

-----Original Message-----
From: Steven Smith [mailto:steven.smith@xxxxxxxxxx] 
Sent: Friday, January 30, 2009 10:04 PM
To: Kumar, Venkat
Cc: Steven Smith; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] GNTTAB_copy

> Steve,
> 
> I have ported the GNTTAB_copy part from netchannel2 xen-unstable to 
> xen-unstable. But the hypercall is failing with a status -1.
> 
> xm dmesg says
> ===========================================
> Bad flags (0) or dom (0). (expected dom 9)
> ===========================================
Okay, so Xen started processing the grant table operation, but found
that the grant entry in the granting domain's grant table was bad
(because it was full of zeroes).  That probably indicates that it was
accessing completely the wrong gref.

> I am granting the page with a flag ( GTF_reading | GTF_writing & 
> GTF_permit_access ) but still it did not work.
> 
> What could be wrong here?
I'm not sure.  I'd suggest you put some printks in your guests (both
the granting one and the HVM one) to make sure that they agree on the
grant reference number, and some in Xen to make sure that it's reading
the hypercall arguments correctly.

Steven.


> -----Original Message-----
> From: Steven Smith [mailto:steven.smith@xxxxxxxxxx]
> Sent: Friday, January 30, 2009 4:52 PM
> To: Kumar, Venkat
> Cc: Steven Smith; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] GNTTAB_copy
> 
> That's unfortunate; the repository works fine for me.
> 
> There aren't any other ways of downloading the entire repository, but
> the changes you need to make are pretty self-contained, so I've
> attached the relevant cset.  You'll need to get rid of the
> GNTTABOP_set_version bits, but apart from that it should all be fairly
> obvious.
> 
> Steven.
> 
> 
> > Steven - Thanks for the pointer.
> > I get an error while downloading the code.
> >
> > =======================================================================
> > hg clone http://xenbits.xensource.com/ext/netchannel2/xen-unstable.hg
> > destination directory: xen-unstable.hg
> > requesting all changes
> > adding changesets
> > transaction abort!
> > rollback completed
> > abort: Connection reset by peer
> > =======================================================================
> >
> > Do you know any alternate download?
> >
> > Venkat
> >
> > -----Original Message-----
> > From: Steven Smith [mailto:steven.smith@xxxxxxxxxx]
> > Sent: Friday, January 30, 2009 4:18 PM
> > To: Kumar, Venkat
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Xen-devel] GNTTAB_copy
> >
> > > Is GNTTAB_copy command in the Hypercall "HYPERVISOR_grant_table_op"
> > > supported between two HVM's?
> > It's not in xen-unstable, no, but it is if you use the netchannel2
> > hypervisor (available from
> > http://xenbits.xensource.com/ext/netchannel2/xen-unstable.hg).  It'd
> > be pretty easy to cross-port, if you wanted to have a go at that.  The
> > interesting cset is this one:
> >
> > changeset:   19112:ea4b9c439ac3
> > user:        Steven Smith <steven.smith@xxxxxxxxxxxxx>
> > date:        Thu Jan 22 09:53:12 2009 +0000
> > files:       xen/arch/x86/hvm/hvm.c xen/include/xen/hypercall.h
> > description:
> > Allow GNTABOP_copy to be used from HVM domains.
> >
> > Steven.

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