iommu: Add ops->domain_alloc_nested()

It turns out all the drivers that are using this immediately call into
another function, so just make that function directly into the op. This
makes paging=NULL for domain_alloc_user and we can remove the argument in
the next patch.

The function mirrors the similar op in the viommu that allocates a nested
domain on top of the viommu's nesting parent. This version supports cases
where a viommu is not being used.

Link: https://patch.msgid.link/r/1-v1-c252ebdeb57b+329-iommu_paging_flags_jgg@nvidia.com
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/intel/iommu.c

@@ -3340,12 +3340,8 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
 	struct iommu_domain *domain;
 	bool first_stage;
 
-	/* Must be NESTING domain */
-	if (parent) {
-		if (!nested_supported(iommu) || flags)
-			return ERR_PTR(-EOPNOTSUPP);
-		return intel_nested_domain_alloc(parent, user_data);
-	}
+	if (parent)
+		return ERR_PTR(-EOPNOTSUPP);
 
 	if (flags &
 	    (~(IOMMU_HWPT_ALLOC_NEST_PARENT | IOMMU_HWPT_ALLOC_DIRTY_TRACKING
@@ -4475,6 +4471,7 @@ const struct iommu_ops intel_iommu_ops = {
 	.domain_alloc_user	= intel_iommu_domain_alloc_user,
 	.domain_alloc_sva	= intel_svm_domain_alloc,
 	.domain_alloc_paging	= intel_iommu_domain_alloc_paging,
+	.domain_alloc_nested	= intel_iommu_domain_alloc_nested,
 	.probe_device		= intel_iommu_probe_device,
 	.release_device		= intel_iommu_release_device,
 	.get_resv_regions	= intel_iommu_get_resv_regions,

drivers/iommu/intel/iommu.h

@@ -1265,8 +1265,10 @@ int __domain_setup_first_level(struct intel_iommu *iommu,
 int dmar_ir_support(void);
 
 void iommu_flush_write_buffer(struct intel_iommu *iommu);
-struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
-					       const struct iommu_user_data *user_data);
+struct iommu_domain *
+intel_iommu_domain_alloc_nested(struct device *dev, struct iommu_domain *parent,
+				u32 flags,
+				const struct iommu_user_data *user_data);
 struct device *device_rbtree_find(struct intel_iommu *iommu, u16 rid);
 
 enum cache_tag_type {

drivers/iommu/intel/nested.c

@@ -186,14 +186,21 @@ static const struct iommu_domain_ops intel_nested_domain_ops = {
 	.cache_invalidate_user	= intel_nested_cache_invalidate_user,
 };
 
-struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
-					       const struct iommu_user_data *user_data)
+struct iommu_domain *
+intel_iommu_domain_alloc_nested(struct device *dev, struct iommu_domain *parent,
+				u32 flags,
+				const struct iommu_user_data *user_data)
 {
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	struct dmar_domain *s2_domain = to_dmar_domain(parent);
+	struct intel_iommu *iommu = info->iommu;
 	struct iommu_hwpt_vtd_s1 vtd;
 	struct dmar_domain *domain;
 	int ret;
 
+	if (!nested_supported(iommu) || flags)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	/* Must be nested domain */
 	if (user_data->type != IOMMU_HWPT_DATA_VTD_S1)
 		return ERR_PTR(-EOPNOTSUPP);

drivers/iommu/iommufd/hw_pagetable.c

@@ -227,7 +227,7 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
 	int rc;
 
 	if ((flags & ~IOMMU_HWPT_FAULT_ID_VALID) ||
-	    !user_data->len || !ops->domain_alloc_user)
+	    !user_data->len || !ops->domain_alloc_nested)
 		return ERR_PTR(-EOPNOTSUPP);
 	if (parent->auto_domain || !parent->nest_parent ||
 	    parent->common.domain->owner != ops)
@@ -242,9 +242,9 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
 	refcount_inc(&parent->common.obj.users);
 	hwpt_nested->parent = parent;
 
-	hwpt->domain = ops->domain_alloc_user(idev->dev,
-					      flags & ~IOMMU_HWPT_FAULT_ID_VALID,
-					      parent->common.domain, user_data);
+	hwpt->domain = ops->domain_alloc_nested(
+		idev->dev, parent->common.domain,
+		flags & ~IOMMU_HWPT_FAULT_ID_VALID, user_data);
 	if (IS_ERR(hwpt->domain)) {
 		rc = PTR_ERR(hwpt->domain);
 		hwpt->domain = NULL;

drivers/iommu/iommufd/selftest.c

@@ -356,8 +356,8 @@ __mock_domain_alloc_nested(const struct iommu_user_data *user_data)
 }
 
 static struct iommu_domain *
-mock_domain_alloc_nested(struct iommu_domain *parent, u32 flags,
-			 const struct iommu_user_data *user_data)
+mock_domain_alloc_nested(struct device *dev, struct iommu_domain *parent,
+			 u32 flags, const struct iommu_user_data *user_data)
 {
 	struct mock_iommu_domain_nested *mock_nested;
 	struct mock_iommu_domain *mock_parent;
@@ -391,7 +391,7 @@ mock_domain_alloc_user(struct device *dev, u32 flags,
 	struct iommu_domain *domain;
 
 	if (parent)
-		return mock_domain_alloc_nested(parent, flags, user_data);
+		return ERR_PTR(-EOPNOTSUPP);
 
 	if (user_data)
 		return ERR_PTR(-EOPNOTSUPP);
@@ -719,6 +719,7 @@ static const struct iommu_ops mock_ops = {
 	.hw_info = mock_domain_hw_info,
 	.domain_alloc_paging = mock_domain_alloc_paging,
 	.domain_alloc_user = mock_domain_alloc_user,
+	.domain_alloc_nested = mock_domain_alloc_nested,
 	.capable = mock_domain_capable,
 	.device_group = generic_device_group,
 	.probe_device = mock_probe_device,

include/linux/iommu.h

@@ -559,15 +559,13 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size,
  *                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.
- *                     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
- *                     NULL while the @user_data can be optionally provided, the
+ *                     The @user_data can be optionally provided, the
  *                     new domain must support __IOMMU_DOMAIN_PAGING.
  *                     Upon failure, ERR_PTR must be returned.
  * @domain_alloc_paging: Allocate an iommu_domain that can be used for
  *                       UNMANAGED, DMA, and DMA_FQ domain types.
  * @domain_alloc_sva: Allocate an iommu_domain for Shared Virtual Addressing.
+ * @domain_alloc_nested: Allocate an iommu_domain for nested translation.
  * @probe_device: Add device to iommu driver handling
  * @release_device: Remove device from iommu driver handling
  * @probe_finalize: Do final setup work after the device is added to an IOMMU
@@ -622,6 +620,9 @@ struct iommu_ops {
 	struct iommu_domain *(*domain_alloc_paging)(struct device *dev);
 	struct iommu_domain *(*domain_alloc_sva)(struct device *dev,
 						 struct mm_struct *mm);
+	struct iommu_domain *(*domain_alloc_nested)(
+		struct device *dev, struct iommu_domain *parent, u32 flags,
+		const struct iommu_user_data *user_data);
 
 	struct iommu_device *(*probe_device)(struct device *dev);
 	void (*release_device)(struct device *dev);