iommu: Add IOMMU_DOMAIN_NESTED

Introduce a new domain type for a user I/O page table, which is nested on
top of another user space address represented by a PAGING domain. This
new domain can be allocated by the domain_alloc_user op, and attached to
a device through the existing iommu_attach_device/group() interfaces.

The mappings of a nested domain are managed by user space software, so it
is not necessary to have map/unmap callbacks.

Link: https://lore.kernel.org/r/20231026043938.63898-2-yi.l.liu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 1d42bdb37cbc25020055f12fc75a64d88f715e01..bc303cb2af37acc8bc61fb93cbeaa8cf09d315fe 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -67,6 +67,9 @@ struct iommu_domain_geometry {
 
 #define __IOMMU_DOMAIN_SVA     (1U << 4)  /* Shared process address space */
 
+#define __IOMMU_DOMAIN_NESTED  (1U << 6)  /* User-managed address space nested
+                                             on a stage-2 translation        */
+
 #define IOMMU_DOMAIN_ALLOC_FLAGS ~__IOMMU_DOMAIN_DMA_FQ
 /*
  * This are the possible domain-types
@@ -93,6 +96,7 @@ struct iommu_domain_geometry {
                                 __IOMMU_DOMAIN_DMA_API |       \
                                 __IOMMU_DOMAIN_DMA_FQ)
 #define IOMMU_DOMAIN_SVA       (__IOMMU_DOMAIN_SVA)
+#define IOMMU_DOMAIN_NESTED    (__IOMMU_DOMAIN_NESTED)
 
 struct iommu_domain {
        unsigned type;