iommu/vt-d: Cleanup get_valid_domain_for_dev()

Previously, get_valid_domain_for_dev() is used to retrieve the
DMA domain which has been attached to the device or allocate one
if no domain has been attached yet. As we have delegated the DMA
domain management to upper layer, this function is used purely to
allocate a private DMA domain if the default domain doesn't work
for ths device. Cleanup the code for readability.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -2609,7 +2609,6 @@ static struct dmar_domain *find_or_alloc_domain(struct device *dev, int gaw)
 	}
 
 out:
-
 	return domain;
 }
 
@@ -3558,16 +3557,17 @@ static unsigned long intel_alloc_iova(struct device *dev,
 	return iova_pfn;
 }
 
-struct dmar_domain *get_valid_domain_for_dev(struct device *dev)
+static struct dmar_domain *get_private_domain_for_dev(struct device *dev)
 {
 	struct dmar_domain *domain, *tmp;
 	struct dmar_rmrr_unit *rmrr;
 	struct device *i_dev;
 	int i, ret;
 
+	/* Device shouldn't be attached by any domains. */
 	domain = find_domain(dev);
 	if (domain)
-		goto out;
+		return NULL;
 
 	domain = find_or_alloc_domain(dev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
 	if (!domain)
@@ -3597,11 +3597,9 @@ struct dmar_domain *get_valid_domain_for_dev(struct device *dev)
 	}
 
 out:
-
 	if (!domain)
 		dev_err(dev, "Allocating domain failed\n");
 
-
 	return domain;
 }
 
@@ -3638,7 +3636,7 @@ static bool iommu_need_mapping(struct device *dev)
 				dmar_domain = to_dmar_domain(domain);
 				dmar_domain->flags |= DOMAIN_FLAG_LOSE_CHILDREN;
 			}
-			get_valid_domain_for_dev(dev);
+			get_private_domain_for_dev(dev);
 		}
 
 		dev_info(dev, "32bit DMA uses non-identity mapping\n");
@@ -3660,7 +3658,7 @@ static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
 
 	BUG_ON(dir == DMA_NONE);
 
-	domain = get_valid_domain_for_dev(dev);
+	domain = find_domain(dev);
 	if (!domain)
 		return DMA_MAPPING_ERROR;
 
@@ -3875,7 +3873,7 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
 	if (!iommu_need_mapping(dev))
 		return dma_direct_map_sg(dev, sglist, nelems, dir, attrs);
 
-	domain = get_valid_domain_for_dev(dev);
+	domain = find_domain(dev);
 	if (!domain)
 		return 0;
 
@@ -5547,7 +5545,7 @@ static int intel_iommu_add_device(struct device *dev)
 			ret = iommu_request_dma_domain_for_dev(dev);
 			if (ret) {
 				dmar_domain->flags |= DOMAIN_FLAG_LOSE_CHILDREN;
-				if (!get_valid_domain_for_dev(dev)) {
+				if (!get_private_domain_for_dev(dev)) {
 					dev_warn(dev,
 						 "Failed to get a private domain.\n");
 					return -ENOMEM;
@@ -5640,7 +5638,7 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev)
 	u64 ctx_lo;
 	int ret;
 
-	domain = get_valid_domain_for_dev(dev);
+	domain = find_domain(dev);
 	if (!domain)
 		return -EINVAL;
 

include/linux/intel-iommu.h

@@ -660,7 +660,6 @@ extern int qi_submit_sync(struct qi_desc *desc, struct intel_iommu *iommu);
 
 extern int dmar_ir_support(void);
 
-struct dmar_domain *get_valid_domain_for_dev(struct device *dev);
 void *alloc_pgtable_page(int node);
 void free_pgtable_page(void *vaddr);
 struct intel_iommu *domain_get_iommu(struct dmar_domain *domain);