vfio: powerpc/spapr/iommu/powernv/ioda2: Rework IOMMU ownership control

This adds tce_iommu_take_ownership() and tce_iommu_release_ownership
which call in a loop iommu_take_ownership()/iommu_release_ownership()
for every table on the group. As there is just one now, no change in
behaviour is expected.

At the moment the iommu_table struct has a set_bypass() which enables/
disables DMA bypass on IODA2 PHB. This is exposed to POWERPC IOMMU code
which calls this callback when external IOMMU users such as VFIO are
about to get over a PHB.

The set_bypass() callback is not really an iommu_table function but
IOMMU/PE function. This introduces a iommu_table_group_ops struct and
adds take_ownership()/release_ownership() callbacks to it which are
called when an external user takes/releases control over the IOMMU.

This replaces set_bypass() with ownership callbacks as it is not
necessarily just bypass enabling, it can be something else/more
so let's give it more generic name.

The callbacks is implemented for IODA2 only. Other platforms (P5IOC2,
IODA1) will use the old iommu_take_ownership/iommu_release_ownership API.
The following patches will replace iommu_take_ownership/
iommu_release_ownership calls in IODA2 with full IOMMU table release/
create.

As we here and touching bypass control, this removes
pnv_pci_ioda2_setup_bypass_pe() as it does not do much
more compared to pnv_pci_ioda2_set_bypass. This moves tce_bypass_base
initialization to pnv_pci_ioda2_setup_dma_pe.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[aw: for the vfio related changes]
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 44a20ccf06b4..489133cf7c5e 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -93,7 +93,6 @@ struct iommu_table {
 	unsigned long  it_page_shift;/* table iommu page size */
 	struct list_head it_group_list;/* List of iommu_table_group_link */
 	struct iommu_table_ops *it_ops;
-	void (*set_bypass)(struct iommu_table *tbl, bool enable);
 };
 
 /* Pure 2^n version of get_order */
@@ -126,6 +125,15 @@ extern struct iommu_table *iommu_init_table(struct iommu_table * tbl,
 					    int nid);
 #define IOMMU_TABLE_GROUP_MAX_TABLES	1
 
+struct iommu_table_group;
+
+struct iommu_table_group_ops {
+	/* Switch ownership from platform code to external user (e.g. VFIO) */
+	void (*take_ownership)(struct iommu_table_group *table_group);
+	/* Switch ownership from external user (e.g. VFIO) back to core */
+	void (*release_ownership)(struct iommu_table_group *table_group);
+};
+
 struct iommu_table_group_link {
 	struct list_head next;
 	struct rcu_head rcu;
@@ -135,6 +143,7 @@ struct iommu_table_group_link {
 struct iommu_table_group {
 	struct iommu_group *group;
 	struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
+	struct iommu_table_group_ops *ops;
 };
 
 #ifdef CONFIG_IOMMU_API