On Thu, Feb 20, 2020 at 05:23:20PM +0100, Christian Borntraeger wrote: > >From a users perspective it makes absolutely perfect sense to use the > bounce buffers when they are NEEDED. > Forcing the user to specify iommu_platform just because you need bounce buffers > really feels wrong. And obviously we have a severe performance issue > because of the indirections. The point is that the user should not have to specify iommu_platform. We need to make sure any new hypervisor (especially one that might require bounce buffering) always sets it, as was a rather bogus legacy hack that isn't extensibe for cases that for example require bounce buffering.
