iommu/vt-d: Remove finding domain in dmar_insert_one_dev_info()

The Intel IOMMU driver has already converted to use default domain
framework in iommu core. There's no need to find a domain for the
device in the domain attaching path. Cleanup that code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220214025704.3184654-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20220301020159.633356-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/intel/iommu.c

@@ -2554,7 +2554,6 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 						    struct device *dev,
 						    struct dmar_domain *domain)
 {
-	struct dmar_domain *found = NULL;
 	struct device_domain_info *info;
 	unsigned long flags;
 	int ret;
@@ -2605,26 +2604,6 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 	}
 
 	spin_lock_irqsave(&device_domain_lock, flags);
-	if (dev)
-		found = find_domain(dev);
-
-	if (!found) {
-		struct device_domain_info *info2;
-		info2 = dmar_search_domain_by_dev_info(info->segment, info->bus,
-						       info->devfn);
-		if (info2) {
-			found      = info2->domain;
-			info2->dev = dev;
-		}
-	}
-
-	if (found) {
-		spin_unlock_irqrestore(&device_domain_lock, flags);
-		free_devinfo_mem(info);
-		/* Caller must free the original domain */
-		return found;
-	}
-
 	spin_lock(&iommu->lock);
 	ret = domain_attach_iommu(domain, iommu);
 	spin_unlock(&iommu->lock);