On 08/07/2022 21:55, Jason Gunthorpe wrote:
On Fri, Jul 08, 2022 at 04:34:55PM +1000, Alexey Kardashevskiy wrote:
For now I'll add a comment in spapr_tce_iommu_attach_dev() that it is fine
to do nothing as tce_iommu_take_ownership() and
tce_iommu_take_ownership_ddw() take care of not having active DMA mappings.
That will still cause a security problem because
tce_iommu_take_ownership()/etc are called too late. This is the moment
in the flow when the ownershift must change away from the DMA API that
power implements and to VFIO, not later.
It is getting better and better :)
On POWERNV, at the boot time the platforms sets up PHBs, enables bypass,
creates groups and attaches devices. As for now attaching devices to the
default domain (which is BLOCKED) fails the not-being-use check as
enabled bypass means "everything is mapped for DMA". So at this point
the default domain has to be IOMMU_DOMAIN_IDENTITY or
IOMMU_DOMAIN_UNMANAGED so later on VFIO can move devices to
IOMMU_DOMAIN_BLOCKED. Am I missing something?
Jason
--
Alexey
