iommu/vt-d: Use bitmap_zalloc() when applicable

'iommu->domain_ids' is a bitmap. So use 'bitmap_zalloc()' to simplify code
and improve the semantic.

Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
consistency.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/cb7a3e0a8d522447a06298a4f244c3df072f948b.1635018498.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20211217083817.1745419-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: tititiou36

drivers/iommu/intel/iommu.c

@@ -1878,17 +1878,16 @@ static void iommu_disable_translation(struct intel_iommu *iommu)
 
 static int iommu_init_domains(struct intel_iommu *iommu)
 {
-	u32 ndomains, nlongs;
+	u32 ndomains;
 	size_t size;
 
 	ndomains = cap_ndoms(iommu->cap);
 	pr_debug("%s: Number of Domains supported <%d>\n",
 		 iommu->name, ndomains);
-	nlongs = BITS_TO_LONGS(ndomains);
 
 	spin_lock_init(&iommu->lock);
 
-	iommu->domain_ids = kcalloc(nlongs, sizeof(unsigned long), GFP_KERNEL);
+	iommu->domain_ids = bitmap_zalloc(ndomains, GFP_KERNEL);
 	if (!iommu->domain_ids)
 		return -ENOMEM;
 
@@ -1903,7 +1902,7 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 	if (!iommu->domains || !iommu->domains[0]) {
 		pr_err("%s: Allocating domain array failed\n",
 		       iommu->name);
-		kfree(iommu->domain_ids);
+		bitmap_free(iommu->domain_ids);
 		kfree(iommu->domains);
 		iommu->domain_ids = NULL;
 		iommu->domains    = NULL;
@@ -1964,7 +1963,7 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
 		for (i = 0; i < elems; i++)
 			kfree(iommu->domains[i]);
 		kfree(iommu->domains);
-		kfree(iommu->domain_ids);
+		bitmap_free(iommu->domain_ids);
 		iommu->domains = NULL;
 		iommu->domain_ids = NULL;
 	}