diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 3a74e44..86e2f4a 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -26,6 +26,8 @@
  * These routines are used by both DMA-remapping and Interrupt-remapping
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt /* has to precede printk.h */
+
 #include <linux/pci.h>
 #include <linux/dmar.h>
 #include <linux/iova.h>
@@ -39,8 +41,6 @@
 #include <asm/irq_remapping.h>
 #include <asm/iommu_table.h>
 
-#define PREFIX "DMAR: "
-
 /* No locks are needed as DMA remapping hardware unit
  * list is constructed at boot time and hotplug of
  * these units are not supported by the architecture.
@@ -83,16 +83,12 @@
 		 * ignore it
 		 */
 		if (!bus) {
-			printk(KERN_WARNING
-			PREFIX "Device scope bus [%d] not found\n",
-			scope->bus);
+			pr_warn("Device scope bus [%d] not found\n", scope->bus);
 			break;
 		}
 		pdev = pci_get_slot(bus, PCI_DEVFN(path->dev, path->fn));
 		if (!pdev) {
-			printk(KERN_WARNING PREFIX
-			"Device scope device [%04x:%02x:%02x.%02x] not found\n",
-				segment, bus->number, path->dev, path->fn);
+			/* warning will be printed below */
 			break;
 		}
 		path ++;
@@ -100,9 +96,8 @@
 		bus = pdev->subordinate;
 	}
 	if (!pdev) {
-		printk(KERN_WARNING PREFIX
-		"Device scope device [%04x:%02x:%02x.%02x] not found\n",
-		segment, scope->bus, path->dev, path->fn);
+		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
+			segment, scope->bus, path->dev, path->fn);
 		*dev = NULL;
 		return 0;
 	}
@@ -110,9 +105,8 @@
 			pdev->subordinate) || (scope->entry_type == \
 			ACPI_DMAR_SCOPE_TYPE_BRIDGE && !pdev->subordinate)) {
 		pci_dev_put(pdev);
-		printk(KERN_WARNING PREFIX
-			"Device scope type does not match for %s\n",
-			 pci_name(pdev));
+		pr_warn("Device scope type does not match for %s\n",
+			pci_name(pdev));
 		return -EINVAL;
 	}
 	*dev = pdev;
@@ -134,8 +128,7 @@
 		    scope->entry_type == ACPI_DMAR_SCOPE_TYPE_BRIDGE)
 			(*cnt)++;
 		else if (scope->entry_type != ACPI_DMAR_SCOPE_TYPE_IOAPIC) {
-			printk(KERN_WARNING PREFIX
-			       "Unsupported device scope\n");
+			pr_warn("Unsupported device scope\n");
 		}
 		start += scope->length;
 	}
@@ -261,25 +254,23 @@
 	case ACPI_DMAR_TYPE_HARDWARE_UNIT:
 		drhd = container_of(header, struct acpi_dmar_hardware_unit,
 				    header);
-		printk (KERN_INFO PREFIX
-			"DRHD base: %#016Lx flags: %#x\n",
+		pr_info("DRHD base: %#016Lx flags: %#x\n",
 			(unsigned long long)drhd->address, drhd->flags);
 		break;
 	case ACPI_DMAR_TYPE_RESERVED_MEMORY:
 		rmrr = container_of(header, struct acpi_dmar_reserved_memory,
 				    header);
-		printk (KERN_INFO PREFIX
-			"RMRR base: %#016Lx end: %#016Lx\n",
+		pr_info("RMRR base: %#016Lx end: %#016Lx\n",
 			(unsigned long long)rmrr->base_address,
 			(unsigned long long)rmrr->end_address);
 		break;
 	case ACPI_DMAR_TYPE_ATSR:
 		atsr = container_of(header, struct acpi_dmar_atsr, header);
-		printk(KERN_INFO PREFIX "ATSR flags: %#x\n", atsr->flags);
+		pr_info("ATSR flags: %#x\n", atsr->flags);
 		break;
 	case ACPI_DMAR_HARDWARE_AFFINITY:
 		rhsa = container_of(header, struct acpi_dmar_rhsa, header);
-		printk(KERN_INFO PREFIX "RHSA base: %#016Lx proximity domain: %#x\n",
+		pr_info("RHSA base: %#016Lx proximity domain: %#x\n",
 		       (unsigned long long)rhsa->base_address,
 		       rhsa->proximity_domain);
 		break;
@@ -299,7 +290,7 @@
 				&dmar_tbl_size);
 
 	if (ACPI_SUCCESS(status) && !dmar_tbl) {
-		printk (KERN_WARNING PREFIX "Unable to map DMAR\n");
+		pr_warn("Unable to map DMAR\n");
 		status = AE_NOT_FOUND;
 	}
 
@@ -333,20 +324,18 @@
 		return -ENODEV;
 
 	if (dmar->width < PAGE_SHIFT - 1) {
-		printk(KERN_WARNING PREFIX "Invalid DMAR haw\n");
+		pr_warn("Invalid DMAR haw\n");
 		return -EINVAL;
 	}
 
-	printk (KERN_INFO PREFIX "Host address width %d\n",
-		dmar->width + 1);
+	pr_info("Host address width %d\n", dmar->width + 1);
 
 	entry_header = (struct acpi_dmar_header *)(dmar + 1);
 	while (((unsigned long)entry_header) <
 			(((unsigned long)dmar) + dmar_tbl->length)) {
 		/* Avoid looping forever on bad ACPI tables */
 		if (entry_header->length == 0) {
-			printk(KERN_WARNING PREFIX
-				"Invalid 0-length structure\n");
+			pr_warn("Invalid 0-length structure\n");
 			ret = -EINVAL;
 			break;
 		}
@@ -369,8 +358,7 @@
 #endif
 			break;
 		default:
-			printk(KERN_WARNING PREFIX
-				"Unknown DMAR structure type %d\n",
+			pr_warn("Unknown DMAR structure type %d\n",
 				entry_header->type);
 			ret = 0; /* for forward compatibility */
 			break;
@@ -469,12 +457,12 @@
 	ret = parse_dmar_table();
 	if (ret) {
 		if (ret != -ENODEV)
-			printk(KERN_INFO PREFIX "parse DMAR table failure.\n");
+			pr_info("parse DMAR table failure.\n");
 		return ret;
 	}
 
 	if (list_empty(&dmar_drhd_units)) {
-		printk(KERN_INFO PREFIX "No DMAR devices found\n");
+		pr_info("No DMAR devices found\n");
 		return -ENODEV;
 	}
 
@@ -506,8 +494,7 @@
 			(((unsigned long)dmar) + dmar_tbl->length)) {
 		/* Avoid looping forever on bad ACPI tables */
 		if (entry_header->length == 0) {
-			printk(KERN_WARNING PREFIX
-				"Invalid 0-length structure\n");
+			pr_warn("Invalid 0-length structure\n");
 			return 0;
 		}
 
@@ -558,8 +545,7 @@
 
 		if (ret && irq_remapping_enabled && cpu_has_x2apic &&
 		    dmar->flags & 0x1)
-			printk(KERN_INFO
-			       "Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
+			pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
 
 		if (ret && !no_iommu && !iommu_detected && !dmar_disabled) {
 			iommu_detected = 1;
@@ -579,14 +565,89 @@
 }
 
 
+static void unmap_iommu(struct intel_iommu *iommu)
+{
+	iounmap(iommu->reg);
+	release_mem_region(iommu->reg_phys, iommu->reg_size);
+}
+
+/**
+ * map_iommu: map the iommu's registers
+ * @iommu: the iommu to map
+ * @phys_addr: the physical address of the base resgister
+ *
+ * Memory map the iommu's registers.  Start w/ a single page, and
+ * possibly expand if that turns out to be insufficent.
+ */
+static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
+{
+	int map_size, err=0;
+
+	iommu->reg_phys = phys_addr;
+	iommu->reg_size = VTD_PAGE_SIZE;
+
+	if (!request_mem_region(iommu->reg_phys, iommu->reg_size, iommu->name)) {
+		pr_err("IOMMU: can't reserve memory\n");
+		err = -EBUSY;
+		goto out;
+	}
+
+	iommu->reg = ioremap(iommu->reg_phys, iommu->reg_size);
+	if (!iommu->reg) {
+		pr_err("IOMMU: can't map the region\n");
+		err = -ENOMEM;
+		goto release;
+	}
+
+	iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
+	iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
+
+	if (iommu->cap == (uint64_t)-1 && iommu->ecap == (uint64_t)-1) {
+		err = -EINVAL;
+		warn_invalid_dmar(phys_addr, " returns all ones");
+		goto unmap;
+	}
+
+	/* the registers might be more than one page */
+	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
+			 cap_max_fault_reg_offset(iommu->cap));
+	map_size = VTD_PAGE_ALIGN(map_size);
+	if (map_size > iommu->reg_size) {
+		iounmap(iommu->reg);
+		release_mem_region(iommu->reg_phys, iommu->reg_size);
+		iommu->reg_size = map_size;
+		if (!request_mem_region(iommu->reg_phys, iommu->reg_size,
+					iommu->name)) {
+			pr_err("IOMMU: can't reserve memory\n");
+			err = -EBUSY;
+			goto out;
+		}
+		iommu->reg = ioremap(iommu->reg_phys, iommu->reg_size);
+		if (!iommu->reg) {
+			pr_err("IOMMU: can't map the region\n");
+			err = -ENOMEM;
+			goto release;
+		}
+	}
+	err = 0;
+	goto out;
+
+unmap:
+	iounmap(iommu->reg);
+release:
+	release_mem_region(iommu->reg_phys, iommu->reg_size);
+out:
+	return err;
+}
+
 int alloc_iommu(struct dmar_drhd_unit *drhd)
 {
 	struct intel_iommu *iommu;
-	int map_size;
 	u32 ver;
 	static int iommu_allocated = 0;
 	int agaw = 0;
 	int msagaw = 0;
+	int err;
 
 	if (!drhd->reg_base_addr) {
 		warn_invalid_dmar(0, "");
@@ -600,30 +661,22 @@
 	iommu->seq_id = iommu_allocated++;
 	sprintf (iommu->name, "dmar%d", iommu->seq_id);
 
-	iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
-	if (!iommu->reg) {
-		printk(KERN_ERR "IOMMU: can't map the region\n");
+	err = map_iommu(iommu, drhd->reg_base_addr);
+	if (err) {
+		pr_err("IOMMU: failed to map %s\n", iommu->name);
 		goto error;
 	}
-	iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
-	iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
 
-	if (iommu->cap == (uint64_t)-1 && iommu->ecap == (uint64_t)-1) {
-		warn_invalid_dmar(drhd->reg_base_addr, " returns all ones");
-		goto err_unmap;
-	}
-
+	err = -EINVAL;
 	agaw = iommu_calculate_agaw(iommu);
 	if (agaw < 0) {
-		printk(KERN_ERR
-		       "Cannot get a valid agaw for iommu (seq_id = %d)\n",
-		       iommu->seq_id);
+		pr_err("Cannot get a valid agaw for iommu (seq_id = %d)\n",
+			iommu->seq_id);
 		goto err_unmap;
 	}
 	msagaw = iommu_calculate_max_sagaw(iommu);
 	if (msagaw < 0) {
-		printk(KERN_ERR
-			"Cannot get a valid max agaw for iommu (seq_id = %d)\n",
+		pr_err("Cannot get a valid max agaw for iommu (seq_id = %d)\n",
 			iommu->seq_id);
 		goto err_unmap;
 	}
@@ -632,19 +685,6 @@
 
 	iommu->node = -1;
 
-	/* the registers might be more than one page */
-	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
-		cap_max_fault_reg_offset(iommu->cap));
-	map_size = VTD_PAGE_ALIGN(map_size);
-	if (map_size > VTD_PAGE_SIZE) {
-		iounmap(iommu->reg);
-		iommu->reg = ioremap(drhd->reg_base_addr, map_size);
-		if (!iommu->reg) {
-			printk(KERN_ERR "IOMMU: can't map the region\n");
-			goto error;
-		}
-	}
-
 	ver = readl(iommu->reg + DMAR_VER_REG);
 	pr_info("IOMMU %d: reg_base_addr %llx ver %d:%d cap %llx ecap %llx\n",
 		iommu->seq_id,
@@ -659,10 +699,10 @@
 	return 0;
 
  err_unmap:
-	iounmap(iommu->reg);
+	unmap_iommu(iommu);
  error:
 	kfree(iommu);
-	return -1;
+	return err;
 }
 
 void free_iommu(struct intel_iommu *iommu)
@@ -673,7 +713,8 @@
 	free_dmar_iommu(iommu);
 
 	if (iommu->reg)
-		iounmap(iommu->reg);
+		unmap_iommu(iommu);
+
 	kfree(iommu);
 }
 
@@ -710,7 +751,7 @@
 	if (fault & DMA_FSTS_IQE) {
 		head = readl(iommu->reg + DMAR_IQH_REG);
 		if ((head >> DMAR_IQ_SHIFT) == index) {
-			printk(KERN_ERR "VT-d detected invalid descriptor: "
+			pr_err("VT-d detected invalid descriptor: "
 				"low=%llx, high=%llx\n",
 				(unsigned long long)qi->desc[index].low,
 				(unsigned long long)qi->desc[index].high);
@@ -1129,15 +1170,14 @@
 	reason = dmar_get_fault_reason(fault_reason, &fault_type);
 
 	if (fault_type == INTR_REMAP)
-		printk(KERN_ERR "INTR-REMAP: Request device [[%02x:%02x.%d] "
+		pr_err("INTR-REMAP: Request device [[%02x:%02x.%d] "
 		       "fault index %llx\n"
 			"INTR-REMAP:[fault reason %02d] %s\n",
 			(source_id >> 8), PCI_SLOT(source_id & 0xFF),
 			PCI_FUNC(source_id & 0xFF), addr >> 48,
 			fault_reason, reason);
 	else
-		printk(KERN_ERR
-		       "DMAR:[%s] Request device [%02x:%02x.%d] "
+		pr_err("DMAR:[%s] Request device [%02x:%02x.%d] "
 		       "fault addr %llx \n"
 		       "DMAR:[fault reason %02d] %s\n",
 		       (type ? "DMA Read" : "DMA Write"),
@@ -1157,8 +1197,7 @@
 	raw_spin_lock_irqsave(&iommu->register_lock, flag);
 	fault_status = readl(iommu->reg + DMAR_FSTS_REG);
 	if (fault_status)
-		printk(KERN_ERR "DRHD: handling fault status reg %x\n",
-		       fault_status);
+		pr_err("DRHD: handling fault status reg %x\n", fault_status);
 
 	/* TBD: ignore advanced fault log currently */
 	if (!(fault_status & DMA_FSTS_PPF))
@@ -1224,7 +1263,7 @@
 
 	irq = create_irq();
 	if (!irq) {
-		printk(KERN_ERR "IOMMU: no free vectors\n");
+		pr_err("IOMMU: no free vectors\n");
 		return -EINVAL;
 	}
 
@@ -1241,7 +1280,7 @@
 
 	ret = request_irq(irq, dmar_fault, IRQF_NO_THREAD, iommu->name, iommu);
 	if (ret)
-		printk(KERN_ERR "IOMMU: can't request irq\n");
+		pr_err("IOMMU: can't request irq\n");
 	return ret;
 }
 
@@ -1258,8 +1297,7 @@
 		ret = dmar_set_interrupt(iommu);
 
 		if (ret) {
-			printk(KERN_ERR "DRHD %Lx: failed to enable fault, "
-			       " interrupt, ret %d\n",
+			pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",
 			       (unsigned long long)drhd->reg_base_addr, ret);
 			return -1;
 		}
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index e6ca56d..78e2ada 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -308,6 +308,8 @@
 
 struct intel_iommu {
 	void __iomem	*reg; /* Pointer to hardware regs, virtual addr */
+	u64 		reg_phys; /* physical address of hw register set */
+	u64		reg_size; /* size of hw register set */
 	u64		cap;
 	u64		ecap;
 	u32		gcmd; /* Holds TE, EAFL. Don't need SRTP, SFL, WBF */