[PATCH RFCv1 07/14] iommufd: Add viommu set/unset_dev_id ops

[Nicolin Chen]

Add a pair of ops to set and unet device's virtual ID that belongs to
a viommu object. They will be used, in the following patch, by iommufd
to support some HW-acceleration feature from the host level.

For instance, every device behind an ARM SMMU has a Stream ID. The ID
is used by ATC invalidation commands so SMMU HW can direct invalidation
requests to the corresponding PCI device where the ID belongs to. In a
virtualization use case, a passthroughed device in the VM will have a
virtuail Stream ID, used by the ATC invalidation commands in the guest
system. NVIDIA's CMDQV extension for SMMUv3 provides a v-interface to
execute the guest-level ATC invalidation commands directly, yet needs
the HW to be aware of its virtual Stream ID so it can replace with its
physical Stream ID.

Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 include/linux/iommufd.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index dec10c6bb261..ca6ac8a1ffd0 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -94,9 +94,13 @@ struct iommufd_viommu {
  * struct iommufd_viommu_ops - viommu specific operations
  * @free: Free all driver-specific parts of an iommufd_viommu. The memory
  *        of the entire viommu will be free-ed by iommufd core
+ * @set/unset_dev_id: set/unset a user space virtual id for a device
  */
 struct iommufd_viommu_ops {
 	void (*free)(struct iommufd_viommu *viommu);
+	int (*set_dev_id)(struct iommufd_viommu *viommu,
+			  struct device *dev, u64 dev_id);
+	void (*unset_dev_id)(struct iommufd_viommu *viommu, struct device *dev);
 };
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
-- 
2.43.0