iommu/amd: Introduce protection_domain_init() function

This function contains the common parts between the
initialization of dma_ops_domains and usual protection
domains. This also fixes a long-standing bug which was
uncovered by recent changes, in which the api_lock was not
initialized for dma_ops_domains.
Reported-by: NGeorge Wang <xuw2015@gmail.com>
Tested-by: NGeorge Wang <xuw2015@gmail.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -116,6 +116,7 @@ struct kmem_cache *amd_iommu_irq_cache;
 
 static void update_domain(struct protection_domain *domain);
 static int alloc_passthrough_domain(void);
+static int protection_domain_init(struct protection_domain *domain);
 
 /****************************************************************************
  *
@@ -1880,12 +1881,9 @@ static struct dma_ops_domain *dma_ops_domain_alloc(void)
 	if (!dma_dom)
 		return NULL;
 
-	spin_lock_init(&dma_dom->domain.lock);
-
-	dma_dom->domain.id = domain_id_alloc();
-	if (dma_dom->domain.id == 0)
+	if (protection_domain_init(&dma_dom->domain))
 		goto free_dma_dom;
-	INIT_LIST_HEAD(&dma_dom->domain.dev_list);
+
 	dma_dom->domain.mode = PAGE_MODE_2_LEVEL;
 	dma_dom->domain.pt_root = (void *)get_zeroed_page(GFP_KERNEL);
 	dma_dom->domain.flags = PD_DMA_OPS_MASK;
@@ -2915,6 +2913,18 @@ static void protection_domain_free(struct protection_domain *domain)
 	kfree(domain);
 }
 
+static int protection_domain_init(struct protection_domain *domain)
+{
+	spin_lock_init(&domain->lock);
+	mutex_init(&domain->api_lock);
+	domain->id = domain_id_alloc();
+	if (!domain->id)
+		return -ENOMEM;
+	INIT_LIST_HEAD(&domain->dev_list);
+
+	return 0;
+}
+
 static struct protection_domain *protection_domain_alloc(void)
 {
 	struct protection_domain *domain;
@@ -2923,12 +2933,8 @@ static struct protection_domain *protection_domain_alloc(void)
 	if (!domain)
 		return NULL;
 
-	spin_lock_init(&domain->lock);
-	mutex_init(&domain->api_lock);
-	domain->id = domain_id_alloc();
-	if (!domain->id)
+	if (protection_domain_init(domain))
 		goto out_err;
-	INIT_LIST_HEAD(&domain->dev_list);
 
 	add_domain_to_list(domain);