linux-kernel - RE: [Xen-devel] Regressions in v3.3-rc1 introduced by "xen/granttable: Grant tables V2 implementation"

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Date:	Wed, 25 Jan 2012 15:49:52 +0000
From:	Ian Campbell <Ian.Campbell@...rix.com>
To:	Paul Durrant <Paul.Durrant@...rix.com>
CC:	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"Konrad Rzeszutek Wilk (konrad.wilk@...cle.com)" 
	<konrad.wilk@...cle.com>,
	"ANNIE LI (annie.li@...cle.com)" <annie.li@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [Xen-devel] Regressions in v3.3-rc1 introduced by
 "xen/granttable: Grant tables V2 implementation"

On Wed, 2012-01-25 at 15:23 +0000, Paul Durrant wrote:
> > -----Original Message-----
> > From: Paul Durrant
> > Sent: 25 January 2012 07:17
> > To: Ian Campbell; Konrad Rzeszutek Wilk
> > Cc: annie.li@...cle.com; xen-devel@...ts.xensource.com; linux-
> > kernel@...r.kernel.org
> > Subject: RE: [Xen-devel] Regressions in v3.3-rc1 introduced by
> > "xen/granttable: Grant tables V2 implementation"
> > 
> > > -----Original Message-----
> > >
> > > On HVM for gnttab_shared we make an add_to_physmap call with
> > > XENMAPSPACE_grant_table (in gnttab_map). I don't see any support call
> > > to do something similar for the status array though and I don't see a
> > > XENMAPSPACE_* specifically for that case either in the hypervisor either.
> > >
> > 
> > There is no map-space for the status pages. To map them you use the
> > standard map space but OR a bit (top bit IIRC) into in the idx. It's a bit icky,
> > but that's how it is.
> > 
> 
> I fixed a bug in xen-unstable a few weeks back that prevented mapping
> of the status frames so I guess the bug is possibly due to trying to
> use gnttab 2 on 4.1, where this bug would hit, but failing to check
> the return code from the status mapping hypercall?

That bit in the Linux code seems to be correct, at least by inspection.

Ian.


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