iommu/viommu: Add cache_invalidate to iommufd_viommu_ops

This per-vIOMMU cache_invalidate op is like the cache_invalidate_user op
in struct iommu_domain_ops, but wider, supporting device cache (e.g. PCI
ATC invaldiations).

Link: https://patch.msgid.link/r/90138505850fa6b165135e78a87b4cc7022869a4.1730836308.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: nicolinc

include/linux/iommufd.h

@@ -16,6 +16,7 @@ struct device;
 struct file;
 struct iommu_group;
 struct iommu_user_data;
+struct iommu_user_data_array;
 struct iommufd_access;
 struct iommufd_ctx;
 struct iommufd_device;
@@ -105,12 +106,21 @@ struct iommufd_viommu {
  *                       must be defined in include/uapi/linux/iommufd.h.
  *                       It must fully initialize the new iommu_domain before
  *                       returning. Upon failure, ERR_PTR must be returned.
+ * @cache_invalidate: Flush hardware cache used by a vIOMMU. It can be used for
+ *                    any IOMMU hardware specific cache: TLB and device cache.
+ *                    The @array passes in the cache invalidation requests, in
+ *                    form of a driver data structure. A driver must update the
+ *                    array->entry_num to report the number of handled requests.
+ *                    The data structure of the array entry must be defined in
+ *                    include/uapi/linux/iommufd.h
  */
 struct iommufd_viommu_ops {
 	void (*destroy)(struct iommufd_viommu *viommu);
 	struct iommu_domain *(*alloc_domain_nested)(
 		struct iommufd_viommu *viommu, u32 flags,
 		const struct iommu_user_data *user_data);
+	int (*cache_invalidate)(struct iommufd_viommu *viommu,
+				struct iommu_user_data_array *array);
 };
 
 #if IS_ENABLED(CONFIG_IOMMUFD)