On Tue, Sep 20, 2022 at 11:04:57PM +1000, Alexey Kardashevskiy wrote:

Up until now PPC64 managed to avoid using iommu_ops. The VFIO driver
uses a SPAPR TCE sub-driver and all iommu_ops uses were kept in
the Type1 VFIO driver. Recent development added 2 uses of iommu_ops to
the generic VFIO which broke POWER:
- a coherency capability check;
- blocking IOMMU domain - iommu_group_dma_owner_claimed()/...

This adds a simple iommu_ops which reports support for cache
coherency and provides a basic support for blocking domains. No other
domain types are implemented so the default domain is NULL.

Since now iommu_ops controls the group ownership, this takes it out of
VFIO.

This adds an IOMMU device into a pci_controller (=PHB) and registers it
in the IOMMU subsystem, iommu_ops is registered at this point.
This setup is done in postcore_initcall_sync.

This replaces iommu_group_add_device() with iommu_probe_device() as
the former misses necessary steps in connecting PCI devices to IOMMU
devices. This adds a comment about why explicit iommu_probe_device()
is still needed.

Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence")
Fixes: 70693f470848 ("vfio: Set DMA ownership for VFIO devices")
Cc: Deming Wang <redacted>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <redacted>
Cc: Daniel Henrique Barboza <redacted>
Cc: Fabiano Rosas <redacted>
Cc: Murilo Opsfelder Araujo <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Alexey Kardashevskiy <redacted>
---
Changes:
v2:
* replaced a default domain with blocked

Code wise this is much better..

But it is a bit unsettling to see the blocked domain co-opted to mean
'some platform specific VFIO behavior' - don't have a better idea for
this series though.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason