On Sat, Oct 02, 2021 at 02:21:38PM +1000, david@xxxxxxxxxxxxxxxxxxxxx wrote: > > > No. qemu needs to supply *both* the 32-bit and 64-bit range to its > > > guest, and therefore needs to request both from the host. > > > > As I understood your remarks each IOAS can only be one of the formats > > as they have a different PTE layout. So here I ment that qmeu needs to > > be able to pick *for each IOAS* which of the two formats it is. > > No. Both windows are in the same IOAS. A device could do DMA > simultaneously to both windows. Sure, but that doesn't force us to model it as one IOAS in the iommufd. A while back you were talking about using nesting and 3 IOAS's, right? 1, 2 or 3 IOAS's seems like a decision we can make. PASID support will already require that a device can be multi-bound to many IOAS's, couldn't PPC do the same with the windows? Jason
