iommu/amd: Add helper functions to update domain->pt_root

Do not call atomic64_set() directly to update the domain page-table
root and use two new helper functions.

This makes it easier to implement additional work necessary when
the page-table is updated.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200626080547.24865-2-joro@8bytes.org

drivers/iommu/amd/iommu.c

@@ -162,7 +162,18 @@ static void amd_iommu_domain_get_pgtable(struct protection_domain *domain,
 	pgtable->mode = pt_root & 7; /* lowest 3 bits encode pgtable mode */
 }
 
-static u64 amd_iommu_domain_encode_pgtable(u64 *root, int mode)
+static void amd_iommu_domain_set_pt_root(struct protection_domain *domain, u64 root)
+{
+	atomic64_set(&domain->pt_root, root);
+}
+
+static void amd_iommu_domain_clr_pt_root(struct protection_domain *domain)
+{
+	amd_iommu_domain_set_pt_root(domain, 0);
+}
+
+static void amd_iommu_domain_set_pgtable(struct protection_domain *domain,
+					 u64 *root, int mode)
 {
 	u64 pt_root;
 
@@ -170,7 +181,7 @@ static u64 amd_iommu_domain_encode_pgtable(u64 *root, int mode)
 	pt_root = mode & 7;
 	pt_root |= (u64)root;
 
-	return pt_root;
+	amd_iommu_domain_set_pt_root(domain, pt_root);
 }
 
 static struct iommu_dev_data *alloc_dev_data(u16 devid)
@@ -1410,7 +1421,7 @@ static bool increase_address_space(struct protection_domain *domain,
 	struct domain_pgtable pgtable;
 	unsigned long flags;
 	bool ret = true;
-	u64 *pte, root;
+	u64 *pte;
 
 	spin_lock_irqsave(&domain->lock, flags);
 
@@ -1438,8 +1449,7 @@ static bool increase_address_space(struct protection_domain *domain,
 	 * Device Table needs to be updated and flushed before the new root can
 	 * be published.
 	 */
-	root = amd_iommu_domain_encode_pgtable(pte, pgtable.mode);
-	atomic64_set(&domain->pt_root, root);
+	amd_iommu_domain_set_pgtable(domain, pte, pgtable.mode);
 
 	ret = true;
 
@@ -2319,7 +2329,7 @@ static void protection_domain_free(struct protection_domain *domain)
 		domain_id_free(domain->id);
 
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
-	atomic64_set(&domain->pt_root, 0);
+	amd_iommu_domain_clr_pt_root(domain);
 	free_pagetable(&pgtable);
 
 	kfree(domain);
@@ -2327,7 +2337,7 @@ static void protection_domain_free(struct protection_domain *domain)
 
 static int protection_domain_init(struct protection_domain *domain, int mode)
 {
-	u64 *pt_root = NULL, root;
+	u64 *pt_root = NULL;
 
 	BUG_ON(mode < PAGE_MODE_NONE || mode > PAGE_MODE_6_LEVEL);
 
@@ -2343,8 +2353,7 @@ static int protection_domain_init(struct protection_domain *domain, int mode)
 			return -ENOMEM;
 	}
 
-	root = amd_iommu_domain_encode_pgtable(pt_root, mode);
-	atomic64_set(&domain->pt_root, root);
+	amd_iommu_domain_set_pgtable(domain, pt_root, mode);
 
 	return 0;
 }
@@ -2713,8 +2722,8 @@ void amd_iommu_domain_direct_map(struct iommu_domain *dom)
 	/* First save pgtable configuration*/
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
 
-	/* Update data structure */
-	atomic64_set(&domain->pt_root, 0);
+	/* Remove page-table from domain */
+	amd_iommu_domain_clr_pt_root(domain);
 
 	/* Make changes visible to IOMMUs */
 	update_domain(domain);