iommu: Add DMA ownership management interfaces

Multiple devices may be placed in the same IOMMU group because they
cannot be isolated from each other. These devices must either be
entirely under kernel control or userspace control, never a mixture.

This adds dma ownership management in iommu core and exposes several
interfaces for the device drivers and the device userspace assignment
framework (i.e. VFIO), so that any conflict between user and kernel
controlled dma could be detected at the beginning.

The device driver oriented interfaces are,

	int iommu_device_use_default_domain(struct device *dev);
	void iommu_device_unuse_default_domain(struct device *dev);

By calling iommu_device_use_default_domain(), the device driver tells
the iommu layer that the device dma is handled through the kernel DMA
APIs. The iommu layer will manage the IOVA and use the default domain
for DMA address translation.

The device user-space assignment framework oriented interfaces are,

	int iommu_group_claim_dma_owner(struct iommu_group *group,
					void *owner);
	void iommu_group_release_dma_owner(struct iommu_group *group);
	bool iommu_group_dma_owner_claimed(struct iommu_group *group);

The device userspace assignment must be disallowed if the DMA owner
claiming interface returns failure.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20220418005000.897664-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9208eca4b0d1..77972ef978b5 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -675,6 +675,13 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev,
 void iommu_sva_unbind_device(struct iommu_sva *handle);
 u32 iommu_sva_get_pasid(struct iommu_sva *handle);
 
+int iommu_device_use_default_domain(struct device *dev);
+void iommu_device_unuse_default_domain(struct device *dev);
+
+int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
+void iommu_group_release_dma_owner(struct iommu_group *group);
+bool iommu_group_dma_owner_claimed(struct iommu_group *group);
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1031,6 +1038,30 @@ static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
 {
 	return NULL;
 }
+
+static inline int iommu_device_use_default_domain(struct device *dev)
+{
+	return 0;
+}
+
+static inline void iommu_device_unuse_default_domain(struct device *dev)
+{
+}
+
+static inline int
+iommu_group_claim_dma_owner(struct iommu_group *group, void *owner)
+{
+	return -ENODEV;
+}
+
+static inline void iommu_group_release_dma_owner(struct iommu_group *group)
+{
+}
+
+static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
+{
+	return false;
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**