question on "powerpc/pseries/dma: Allow SWIOTLB"

[Christoph Hellwig]

On Fri, Jul 19, 2019 at 05:52:37PM +1000, Alexey Kardashevskiy wrote:
> 
> 
> On 19/07/2019 17:10, Christoph Hellwig wrote:
> > Hey Alexey,
> > 
> > what is the use case for the above commit?  Shouldn't we handle all
> > addressing limits using the iommu?
> 
> Our secure VMs is the use case, when only a fraction of system memory is
> available for DMA.

But shouldn't we force usage of the direct ops in that case as the
IOMMU is not neededed at all?  Also isn't that support non-upstream so
far?