Re: [Xen-devel] [PATCH 2/4] iommu: generalize iommu_inclusive_mapping

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Jul 31, 2018 at 09:27:03AM +0100, Paul Durrant wrote:
> > -----Original Message-----
> > From: Roger Pau Monne
> > Sent: 31 July 2018 09:16
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Kevin Tian <kevin.tian@xxxxxxxxx>;
> > Stefano Stabellini <sstabellini@xxxxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>;
> > George Dunlap <George.Dunlap@xxxxxxxxxx>; Andrew Cooper
> > <Andrew.Cooper3@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Tim
> > (Xen.org) <tim@xxxxxxx>; Julien Grall <julien.grall@xxxxxxx>; Jan Beulich
> > <jbeulich@xxxxxxxx>
> > Subject: Re: [Xen-devel] [PATCH 2/4] iommu: generalize
> > iommu_inclusive_mapping
> > 
> > On Tue, Jul 31, 2018 at 08:18:36AM +0100, Paul Durrant wrote:
> > > > -----Original Message-----
> > > > From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> > Behalf
> > > > Of Roger Pau Monne
> > > > Sent: 27 July 2018 16:32
> > > > To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>; Stefano Stabellini
> > > > <sstabellini@xxxxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>; George Dunlap
> > > > <George.Dunlap@xxxxxxxxxx>; Andrew Cooper
> > > > <Andrew.Cooper3@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>;
> > Tim
> > > > (Xen.org) <tim@xxxxxxx>; Julien Grall <julien.grall@xxxxxxx>; Jan
> > Beulich
> > > > <jbeulich@xxxxxxxx>; Roger Pau Monne <roger.pau@xxxxxxxxxx>
> > > > Subject: [Xen-devel] [PATCH 2/4] iommu: generalize
> > > > iommu_inclusive_mapping
> > > >
> > > > Introduce a new iommu=inclusive generic option that supersedes
> > > > iommu_inclusive_mapping. This should be a non-functional change on
> > > > Intel hardware, while AMD hardware will gain the same functionality of
> > > > mapping almost everything below the 4GB boundary.
> > > >
> > > > Note that is a noop for ARM hardware.
> > > >
> > > > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > > > ---
> > > > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > > Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> > > > Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> > > > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > > > Cc: Julien Grall <julien.grall@xxxxxxx>
> > > > Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > > > Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > > > Cc: Tim Deegan <tim@xxxxxxx>
> > > > Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > > > ---
> > > >  docs/misc/xen-command-line.markdown   | 14 ++++++
> > > >  xen/drivers/passthrough/arm/iommu.c   |  4 ++
> > > >  xen/drivers/passthrough/iommu.c       |  6 +++
> > > >  xen/drivers/passthrough/vtd/extern.h  |  2 -
> > > >  xen/drivers/passthrough/vtd/iommu.c   |  6 ---
> > > >  xen/drivers/passthrough/vtd/x86/vtd.c | 66 +------------------------
> > > >  xen/drivers/passthrough/x86/iommu.c   | 70
> > > > +++++++++++++++++++++++++++
> > > >  xen/include/xen/iommu.h               |  2 +
> > > >  8 files changed, 97 insertions(+), 73 deletions(-)
> > > >
> > > > diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-
> > > > command-line.markdown
> > > > index 65b4754418..91a8bfc9a6 100644
> > > > --- a/docs/misc/xen-command-line.markdown
> > > > +++ b/docs/misc/xen-command-line.markdown
> > > > @@ -1198,6 +1198,17 @@ detection of systems known to misbehave
> > upon
> > > > accesses to that port.
> > > >
> > > >  >> Enable IOMMU debugging code (implies `verbose`).
> > > >
> > > > +> `inclusive`
> > >
> > > This is a dom0 (or hwdom) specific setting so perhaps dom0-inclusive?
> > >
> > > Actually the dom0 iommu options are starting to get unwieldy as they are
> > conflated with the general host iommu options so I think it may be
> > worthwhile splitting things out into a separate 'dom0-iommu=' top level
> > parameter at this stage. (My reasons are slightly selfish as I intend to add
> > another dom0 iommu option to give it just reserved regions, to avoid
> > unnecessary set-up if we know it will be using PV-IOMMU).
> > 
> > Mapping just the reserved regions is what I actually do for PVH with
> > iommu=inclusive (patch 4/4), so maybe it would make sense to speak about
> > the
> > naming here in order to use the same naming for PV and PVH.
> > 
> > TBH I don't really like the dom0- prefix, the command line iommu
> > options either apply to all domains or Dom0 only, having
> > domu-inclusive for example makes no sense IMO.
> 
> No, I think there are some options that you may want to apply to dom0 only, 
> but these are more like the dom0_mem or dom0_max_vpus options. Particularly, 
> the inclusive option is probably something that is only desirable for dom0. 
> Clearly dom0-passthrough and dom0-strict are already defined to relate to 
> dom0 only, and options such as 'reserved' should only be specific on the 
> command line in relation to dom0 IMO. For other domains such an option should 
> be specified via xl.cfg.

Yes, we already have a bunch of those, so then I think dom0-inclusive
and dom0-reserved would be appropriate?

dom0-inclusive-mapping or dom0-reserved-mapping seems too long.

Thanks, Roger.

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