Re: [PATCH 00/22 v2] Introduce default domains for iommu groups

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

Hi Joerg,

On Thu, May 28, 2015 at 05:41:23PM +0100, Joerg Roedel wrote:
> here is the second version of my patch-set to introduce
> default domains into the iommu core. This time it has a lot
> more patches, mostly because I added a proof of concept
> implementation by converting the AMD IOMMU driver to make
> use of it.

Most of this looks fine to me, modulo by comments about the dm regions
(which I'm not sure how to implement for ARM).

> Converting the first driver to the new concept triggered a
> lot of changes and extensions in the patch-set to fit all
> the needs of a more complex iommu driver. Converting other
> drivers might need further changes, but that is something
> for the future.
> 
> A major change is that now the default domain has to be
> allocated by the code that allocates the iommu group. For
> PCI devices this happens in the IOMMU core, but drivers
> allocating the group on their own can now implement a policy
> that fits their needs (e.g. not allocate one domain per
> group but let multiple groups share one domain).

Makes sense. I really think we should be moving group allocation out of
the IOMMU drivers and into the bus code, like we already have for PCI.
Once we've got a way to describe groups of platform devices (e.g. in the
device-tree), then we can have the group creation happen automatically
as part of Laurent's of_iommu work.

Will