On 2/28/25 08:20, Jason Gunthorpe wrote:
virtio-iommu has a mode where the IDENTITY domain is actually a paging
domain with an identity mapping covering some of the system address
space manually created.
To support this add a new domain_alloc_identity() op that accepts
the struct device so that virtio can allocate and fully finalize a
paging domain to return.
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/iommu/iommu.c | 20 ++++++++++++--------
drivers/iommu/virtio-iommu.c | 11 ++---------
include/linux/iommu.h | 4 ++++
3 files changed, 18 insertions(+), 17 deletions(-)
[...]
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 38c65e92ecd091..6389d59178ba3f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -557,6 +557,9 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size,
* @domain_alloc: allocate and return an iommu domain if success. Otherwise
* NULL is returned. The domain is not fully initialized until
* the caller iommu_domain_alloc() returns.
+ * @domain_alloc_identity: allocate an IDENTITY domain. Drivers should prefer to
+ * use identity_domain instead. This should only be used
+ * if dynamic logic is necessary.
* @domain_alloc_paging_flags: Allocate an iommu domain corresponding to the
* input parameters as defined in
* include/uapi/linux/iommufd.h. The @user_data can be
@@ -615,6 +618,7 @@ struct iommu_ops {
/* Domain allocation and freeing by the iommu driver */
struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
+ struct iommu_domain *(*domain_alloc_identity)(struct device *dev);
struct iommu_domain *(*domain_alloc_paging_flags)(
struct device *dev, u32 flags,
const struct iommu_user_data *user_data);
This seems to be a paging domain with identity mappings for some
specific ranges. We make it an IDENTITY domain type because it should be
static and drivers are not allowed to change the mappings once it is
created.
So perhaps naming the callback as domain_alloc_paging_identity, or
domain_alloc_paging_static?
Thanks,
baolu
