iommu/arm-smmu-v3: Add support for domain_alloc_user fn

This will be used by iommufd for allocating usr managed domains and is
also required when we add support for iommufd based dirty tracking
support.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20240703101604.2576-2-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -36,6 +36,8 @@ module_param(disable_msipolling, bool, 0444);
 MODULE_PARM_DESC(disable_msipolling,
 	"Disable MSI-based polling for CMD_SYNC completion.");
 
+static struct iommu_ops arm_smmu_ops;
+
 enum arm_smmu_msi_index {
 	EVTQ_MSI_INDEX,
 	GERROR_MSI_INDEX,
@@ -3020,6 +3022,34 @@ static struct iommu_domain arm_smmu_blocked_domain = {
 	.ops = &arm_smmu_blocked_ops,
 };
 
+static struct iommu_domain *
+arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
+			   struct iommu_domain *parent,
+			   const struct iommu_user_data *user_data)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_domain *smmu_domain;
+	int ret;
+
+	if (flags || parent || user_data)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	smmu_domain = arm_smmu_domain_alloc();
+	if (!smmu_domain)
+		return ERR_PTR(-ENOMEM);
+
+	smmu_domain->domain.type = IOMMU_DOMAIN_UNMANAGED;
+	smmu_domain->domain.ops = arm_smmu_ops.default_domain_ops;
+	ret = arm_smmu_domain_finalise(smmu_domain, master->smmu);
+	if (ret)
+		goto err_free;
+	return &smmu_domain->domain;
+
+err_free:
+	kfree(smmu_domain);
+	return ERR_PTR(ret);
+}
+
 static int arm_smmu_map_pages(struct iommu_domain *domain, unsigned long iova,
 			      phys_addr_t paddr, size_t pgsize, size_t pgcount,
 			      int prot, gfp_t gfp, size_t *mapped)
@@ -3190,8 +3220,6 @@ static void arm_smmu_remove_master(struct arm_smmu_master *master)
 	kfree(master->streams);
 }
 
-static struct iommu_ops arm_smmu_ops;
-
 static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 {
 	int ret;
@@ -3399,6 +3427,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.capable		= arm_smmu_capable,
 	.domain_alloc_paging    = arm_smmu_domain_alloc_paging,
 	.domain_alloc_sva       = arm_smmu_sva_domain_alloc,
+	.domain_alloc_user	= arm_smmu_domain_alloc_user,
 	.probe_device		= arm_smmu_probe_device,
 	.release_device		= arm_smmu_release_device,
 	.device_group		= arm_smmu_device_group,