Re: [PATCH v4 1/3] iommu: introduce domain attribute for nesting IOMMUs

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

On Thu, Sep 25, 2014 at 03:32:33PM +0100, Joerg Roedel wrote:
> On Wed, Sep 24, 2014 at 10:21:23AM +0100, Will Deacon wrote:
> > Some IOMMUs, such as the ARM SMMU, support two stages of translation.
> > The idea behind such a scheme is to allow a guest operating system to
> > use the IOMMU for DMA mappings in the first stage of translation, with
> > the hypervisor then installing mappings in the second stage to provide
> > isolation of the DMA to the physical range assigned to that virtual
> > machine.
> > 
> > In order to allow IOMMU domains to be used for second-stage translation,
> > this patch adds a new iommu_attr (IOMMU_ATTR_NESTING) for setting
> > second-stage domains prior to device attach. The attribute can also be
> > queried to see if a domain is actually making use of nesting.
> > 
> > Cc: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
> > Cc: Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > Signed-off-by: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
> 
> Acked-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>

Thanks, Joerg.

Will