iommu/vt-d: Add nested domain allocation

This adds the support for IOMMU_HWPT_DATA_VTD_S1 type. And 'nested_parent'
is added to mark the nested parent domain to sanitize the input parent domain.

Link: https://lore.kernel.org/r/20231026044216.64964-8-yi.l.liu@intel.comSigned-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/intel/iommu.c

@@ -4077,38 +4077,39 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
 			      struct iommu_domain *parent,
 			      const struct iommu_user_data *user_data)
 {
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	bool dirty_tracking = flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
+	bool nested_parent = flags & IOMMU_HWPT_ALLOC_NEST_PARENT;
+	struct intel_iommu *iommu = info->iommu;
 	struct iommu_domain *domain;
-	struct intel_iommu *iommu;
-	bool dirty_tracking;
+
+	/* Must be NESTING domain */
+	if (parent) {
+		if (!nested_supported(iommu) || flags)
+			return ERR_PTR(-EOPNOTSUPP);
+		return intel_nested_domain_alloc(parent, user_data);
+	}
 
 	if (flags &
 	    (~(IOMMU_HWPT_ALLOC_NEST_PARENT | IOMMU_HWPT_ALLOC_DIRTY_TRACKING)))
 		return ERR_PTR(-EOPNOTSUPP);
-
-	if (parent || user_data)
-		return ERR_PTR(-EOPNOTSUPP);
-
-	iommu = device_to_iommu(dev, NULL, NULL);
-	if (!iommu)
-		return ERR_PTR(-ENODEV);
-
-	if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !nested_supported(iommu))
+	if (nested_parent && !nested_supported(iommu))
 		return ERR_PTR(-EOPNOTSUPP);
-
-	dirty_tracking = (flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING);
-	if (dirty_tracking && !ssads_supported(iommu))
+	if (user_data || (dirty_tracking && !ssads_supported(iommu)))
 		return ERR_PTR(-EOPNOTSUPP);
 
 	/*
-	 * domain_alloc_user op needs to fully initialize a domain
-	 * before return, so uses iommu_domain_alloc() here for
-	 * simple.
+	 * domain_alloc_user op needs to fully initialize a domain before
+	 * return, so uses iommu_domain_alloc() here for simple.
 	 */
 	domain = iommu_domain_alloc(dev->bus);
 	if (!domain)
-		domain = ERR_PTR(-ENOMEM);
+		return ERR_PTR(-ENOMEM);
+
+	if (nested_parent)
+		to_dmar_domain(domain)->nested_parent = true;
 
-	if (!IS_ERR(domain) && dirty_tracking) {
+	if (dirty_tracking) {
 		if (to_dmar_domain(domain)->use_first_level) {
 			iommu_domain_free(domain);
 			return ERR_PTR(-EOPNOTSUPP);

drivers/iommu/intel/iommu.h

@@ -601,6 +601,7 @@ struct dmar_domain {
 					 * level.
 					 */
 	u8 dirty_tracking:1;		/* Dirty tracking is enabled */
+	u8 nested_parent:1;		/* Has other domains nested on it */
 
 	spinlock_t lock;		/* Protect device tracking lists */
 	struct list_head devices;	/* all devices' list */

drivers/iommu/intel/nested.c

@@ -89,7 +89,8 @@ struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
 	/* Must be nested domain */
 	if (user_data->type != IOMMU_HWPT_DATA_VTD_S1)
 		return ERR_PTR(-EOPNOTSUPP);
-	if (parent->ops != intel_iommu_ops.default_domain_ops)
+	if (parent->ops != intel_iommu_ops.default_domain_ops ||
+	    !s2_domain->nested_parent)
 		return ERR_PTR(-EINVAL);
 
 	ret = iommu_copy_struct_from_user(&vtd, user_data,