iommu: Introduce iommu domain types

This allows to handle domains differently based on their
type in the future. An IOMMU driver can implement certain
optimizations for DMA-API domains for example.

The domain types can be extended later and some of the
existing domain attributes can be migrated to become domain
flags.
Tested-by: NThierry Reding <treding@nvidia.com>
Tested-by: NHeiko Stuebner <heiko@sntech.de>
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -909,7 +909,7 @@ struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
 	ops = bus->iommu_ops;
 
 	if (ops->domain_alloc)
-		domain = ops->domain_alloc();
+		domain = ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
 	else
 		domain = kzalloc(sizeof(*domain), GFP_KERNEL);
 
@@ -917,6 +917,7 @@ struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
 		return NULL;
 
 	domain->ops  = bus->iommu_ops;
+	domain->type = IOMMU_DOMAIN_UNMANAGED;
 
 	if (ops->domain_init && domain->ops->domain_init(domain))
 		goto out_free;

include/linux/iommu.h

@@ -51,7 +51,32 @@ struct iommu_domain_geometry {
 	bool force_aperture;       /* DMA only allowed in mappable range? */
 };
 
+/* Domain feature flags */
+#define __IOMMU_DOMAIN_PAGING	(1U << 0)  /* Support for iommu_map/unmap */
+#define __IOMMU_DOMAIN_DMA_API	(1U << 1)  /* Domain for use in DMA-API
+					      implementation              */
+#define __IOMMU_DOMAIN_PT	(1U << 2)  /* Domain is identity mapped   */
+
+/*
+ * This are the possible domain-types
+ *
+ *	IOMMU_DOMAIN_BLOCKED	- All DMA is blocked, can be used to isolate
+ *				  devices
+ *	IOMMU_DOMAIN_IDENTITY	- DMA addresses are system physical addresses
+ *	IOMMU_DOMAIN_UNMANAGED	- DMA mappings managed by IOMMU-API user, used
+ *				  for VMs
+ *	IOMMU_DOMAIN_DMA	- Internally used for DMA-API implementations.
+ *				  This flag allows IOMMU drivers to implement
+ *				  certain optimizations for these domains
+ */
+#define IOMMU_DOMAIN_BLOCKED	(0U)
+#define IOMMU_DOMAIN_IDENTITY	(__IOMMU_DOMAIN_PT)
+#define IOMMU_DOMAIN_UNMANAGED	(__IOMMU_DOMAIN_PAGING)
+#define IOMMU_DOMAIN_DMA	(__IOMMU_DOMAIN_PAGING |	\
+				 __IOMMU_DOMAIN_DMA_API)
+
 struct iommu_domain {
+	unsigned type;
 	const struct iommu_ops *ops;
 	void *priv;
 	iommu_fault_handler_t handler;
@@ -117,7 +142,7 @@ struct iommu_ops {
 	void (*domain_destroy)(struct iommu_domain *domain);
 
 	/* Domain allocation and freeing by the iommu driver */
-	struct iommu_domain *(*domain_alloc)(void);
+	struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
 	void (*domain_free)(struct iommu_domain *);
 
 	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);