iommu: Introduce iommu_paging_domain_alloc_flags()

Currently drivers calls iommu_paging_domain_alloc(dev) to get an
UNMANAGED domain. This is not sufficient to support PASID with
UNMANAGED domain as some HW like AMD requires certain page table type
to support PASIDs.

Also the domain_alloc_paging op only passes device as param for domain
allocation. This is not sufficient for AMD driver to decide the right
page table.

Instead of extending ops->domain_alloc_paging() it was decided to
enhance ops->domain_alloc_user() so that caller can pass various
additional flags.

Hence add iommu_paging_domain_alloc_flags() API which takes flags as
parameter. Caller can pass additional parameter to indicate type of
domain required, etc. iommu_paging_domain_alloc_flags() internally calls
appropriate callback function to allocate a domain.

Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca>
[Added description - Vasant]
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20241028093810.5901-3-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

2 files changed, 38 insertions, 8 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cd91c0eabb34..d82aa6563d84 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1962,20 +1962,42 @@ __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)
 }
 
 /**
- * iommu_paging_domain_alloc() - Allocate a paging domain
+ * iommu_paging_domain_alloc_flags() - Allocate a paging domain
  * @dev: device for which the domain is allocated
+ * @flags: Enum of iommufd_hwpt_alloc_flags
  *
  * Allocate a paging domain which will be managed by a kernel driver. Return
- * allocated domain if successful, or a ERR pointer for failure.
+ * allocated domain if successful, or an ERR pointer for failure.
  */
-struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+struct iommu_domain *iommu_paging_domain_alloc_flags(struct device *dev,
+						     unsigned int flags)
 {
+	const struct iommu_ops *ops;
+	struct iommu_domain *domain;
+
 	if (!dev_has_iommu(dev))
 		return ERR_PTR(-ENODEV);
 
-	return __iommu_domain_alloc(dev_iommu_ops(dev), dev, IOMMU_DOMAIN_UNMANAGED);
+	ops = dev_iommu_ops(dev);
+
+	if (ops->domain_alloc_paging && !flags)
+		domain = ops->domain_alloc_paging(dev);
+	else if (ops->domain_alloc_user)
+		domain = ops->domain_alloc_user(dev, flags, NULL, NULL);
+	else if (ops->domain_alloc && !flags)
+		domain = ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
+	else
+		return ERR_PTR(-EOPNOTSUPP);
+
+	if (IS_ERR(domain))
+		return domain;
+	if (!domain)
+		return ERR_PTR(-ENOMEM);
+
+	iommu_domain_init(domain, IOMMU_DOMAIN_UNMANAGED, ops);
+	return domain;
 }
-EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc);
+EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc_flags);
 
 void iommu_domain_free(struct iommu_domain *domain)
 {
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d93c87f0c003..aa78d911fdda 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -511,8 +511,6 @@ static inline int __iommu_copy_struct_from_user_array(
  *                the caller iommu_domain_alloc() returns.
  * @domain_alloc_user: Allocate an iommu domain corresponding to the input
  *                     parameters as defined in include/uapi/linux/iommufd.h.
- *                     Unlike @domain_alloc, it is called only by IOMMUFD and
- *                     must fully initialize the new domain before return.
  *                     Upon success, if the @user_data is valid and the @parent
  *                     points to a kernel-managed domain, the new domain must be
  *                     IOMMU_DOMAIN_NESTED type; otherwise, the @parent must be
@@ -787,7 +785,11 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 extern int bus_iommu_probe(const struct bus_type *bus);
 extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
 extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
-struct iommu_domain *iommu_paging_domain_alloc(struct device *dev);
+struct iommu_domain *iommu_paging_domain_alloc_flags(struct device *dev, unsigned int flags);
+static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+{
+	return iommu_paging_domain_alloc_flags(dev, 0);
+}
 extern void iommu_domain_free(struct iommu_domain *domain);
 extern int iommu_attach_device(struct iommu_domain *domain,
 			       struct device *dev);
@@ -1078,6 +1080,12 @@ static inline bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 	return false;
 }
 
+struct iommu_domain *iommu_paging_domain_alloc_flags(struct device *dev,
+						     unsigned int flags)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
 {
 	return ERR_PTR(-ENODEV);