On Fri, Jul 19, 2019 at 05:52:37PM +1000, Alexey Kardashevskiy wrote:

On 19/07/2019 17:10, Christoph Hellwig wrote:

quoted

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?