powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domains

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.

The previous discussion is here:
  https://lore.kernel.org/r/20220707135552.3688927-1-aik@ozlabs.ru/
  https://lore.kernel.org/r/20220701061751.1955857-1-aik@ozlabs.ru/

Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence")
Fixes: 70693f470848 ("vfio: Set DMA ownership for VFIO devices")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
[mpe: Fix CONFIG_IOMMU_API=n build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/2000135730.16998523.1678123860135.JavaMail.zimbra@raptorengineeringinc.com

1 files changed, 0 insertions, 8 deletions

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index c3f8ae102ece..a94ec6225d31 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -1200,8 +1200,6 @@ static void tce_iommu_release_ownership(struct tce_container *container,
 	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
 		if (container->tables[i])
 			table_group->ops->unset_window(table_group, i);
-
-	table_group->ops->release_ownership(table_group);
 }
 
 static long tce_iommu_take_ownership(struct tce_container *container,
@@ -1209,10 +1207,6 @@ static long tce_iommu_take_ownership(struct tce_container *container,
 {
 	long i, ret = 0;
 
-	ret = table_group->ops->take_ownership(table_group);
-	if (ret)
-		return ret;
-
 	/* Set all windows to the new group */
 	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
 		struct iommu_table *tbl = container->tables[i];
@@ -1231,8 +1225,6 @@ release_exit:
 	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
 		table_group->ops->unset_window(table_group, i);
 
-	table_group->ops->release_ownership(table_group);
-
 	return ret;
 }