diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 6d1cbdfc9b2a..b64502dfa9f4 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -296,8 +296,13 @@ static int iommu_init_device(struct device *dev)
 	} else
 		dma_pdev = pci_dev_get(pdev);
 
+	/* Account for quirked devices */
 	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
 
+	/*
+	 * If it's a multifunction device that does not support our
+	 * required ACS flags, add to the same group as function 0.
+	 */
 	if (dma_pdev->multifunction &&
 	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
 		swap_pci_ref(&dma_pdev,
@@ -305,14 +310,28 @@ static int iommu_init_device(struct device *dev)
 					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
 					  0)));
 
+	/*
+	 * Devices on the root bus go through the iommu.  If that's not us,
+	 * find the next upstream device and test ACS up to the root bus.
+	 * Finding the next device may require skipping virtual buses.
+	 */
 	while (!pci_is_root_bus(dma_pdev->bus)) {
-		if (pci_acs_path_enabled(dma_pdev->bus->self,
-					 NULL, REQ_ACS_FLAGS))
+		struct pci_bus *bus = dma_pdev->bus;
+
+		while (!bus->self) {
+			if (!pci_is_root_bus(bus))
+				bus = bus->parent;
+			else
+				goto root_bus;
+		}
+
+		if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
 			break;
 
-		swap_pci_ref(&dma_pdev, pci_dev_get(dma_pdev->bus->self));
+		swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
 	}
 
+root_bus:
 	group = iommu_group_get(&dma_pdev->dev);
 	pci_dev_put(dma_pdev);
 	if (!group) {
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 500e7f15f5c2..0a2ea317120a 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1131,9 +1131,6 @@ static int __init amd_iommu_init_pci(void)
 			break;
 	}
 
-	/* Make sure ACS will be enabled */
-	pci_request_acs();
-
 	ret = amd_iommu_init_devices();
 
 	print_iommu_info();
@@ -1652,6 +1649,9 @@ static bool detect_ivrs(void)
 
 	early_acpi_os_unmap_memory((char __iomem *)ivrs_base, ivrs_size);
 
+	/* Make sure ACS will be enabled during PCI probe */
+	pci_request_acs();
+
 	return true;
 }
 
diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 45350ff5e93c..80bad32aa463 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -732,9 +732,9 @@ static int exynos_iommu_domain_init(struct iommu_domain *domain)
 	spin_lock_init(&priv->pgtablelock);
 	INIT_LIST_HEAD(&priv->clients);
 
-	dom->geometry.aperture_start = 0;
-	dom->geometry.aperture_end   = ~0UL;
-	dom->geometry.force_aperture = true;
+	domain->geometry.aperture_start = 0;
+	domain->geometry.aperture_end   = ~0UL;
+	domain->geometry.force_aperture = true;
 
 	domain->priv = priv;
 	return 0;
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 7469b5346643..2297ec193eb4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2008,6 +2008,7 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
 	if (!drhd) {
 		printk(KERN_ERR "IOMMU: can't find DMAR for device %s\n",
 			pci_name(pdev));
+		free_domain_mem(domain);
 		return NULL;
 	}
 	iommu = drhd->iommu;
@@ -4124,8 +4125,13 @@ static int intel_iommu_add_device(struct device *dev)
 	} else
 		dma_pdev = pci_dev_get(pdev);
 
+	/* Account for quirked devices */
 	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
 
+	/*
+	 * If it's a multifunction device that does not support our
+	 * required ACS flags, add to the same group as function 0.
+	 */
 	if (dma_pdev->multifunction &&
 	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
 		swap_pci_ref(&dma_pdev,
@@ -4133,14 +4139,28 @@ static int intel_iommu_add_device(struct device *dev)
 					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
 					  0)));
 
+	/*
+	 * Devices on the root bus go through the iommu.  If that's not us,
+	 * find the next upstream device and test ACS up to the root bus.
+	 * Finding the next device may require skipping virtual buses.
+	 */
 	while (!pci_is_root_bus(dma_pdev->bus)) {
-		if (pci_acs_path_enabled(dma_pdev->bus->self,
-					 NULL, REQ_ACS_FLAGS))
+		struct pci_bus *bus = dma_pdev->bus;
+
+		while (!bus->self) {
+			if (!pci_is_root_bus(bus))
+				bus = bus->parent;
+			else
+				goto root_bus;
+		}
+
+		if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
 			break;
 
-		swap_pci_ref(&dma_pdev, pci_dev_get(dma_pdev->bus->self));
+		swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
 	}
 
+root_bus:
 	group = iommu_group_get(&dma_pdev->dev);
 	pci_dev_put(dma_pdev);
 	if (!group) {
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 4ba325ab6262..2a4bb36bc688 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -799,14 +799,14 @@ static void smmu_iommu_detach_dev(struct iommu_domain *domain,
 			goto out;
 		}
 	}
-	dev_err(smmu->dev, "Couldn't find %s\n", dev_name(c->dev));
+	dev_err(smmu->dev, "Couldn't find %s\n", dev_name(dev));
 out:
 	spin_unlock(&as->client_lock);
 }
 
 static int smmu_iommu_domain_init(struct iommu_domain *domain)
 {
-	int i, err = -ENODEV;
+	int i, err = -EAGAIN;
 	unsigned long flags;
 	struct smmu_as *as;
 	struct smmu_device *smmu = smmu_handle;
@@ -814,11 +814,14 @@ static int smmu_iommu_domain_init(struct iommu_domain *domain)
 	/* Look for a free AS with lock held */
 	for  (i = 0; i < smmu->num_as; i++) {
 		as = &smmu->as[i];
-		if (!as->pdir_page) {
-			err = alloc_pdir(as);
-			if (!err)
-				goto found;
-		}
+
+		if (as->pdir_page)
+			continue;
+
+		err = alloc_pdir(as);
+		if (!err)
+			goto found;
+
 		if (err != -EAGAIN)
 			break;
 	}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 54d6d690073c..7e83370e6fd2 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -20,6 +20,7 @@
 #define __LINUX_IOMMU_H
 
 #include <linux/errno.h>
+#include <linux/types.h>
 
 #define IOMMU_READ	(1)
 #define IOMMU_WRITE	(2)
@@ -30,6 +31,7 @@ struct iommu_group;
 struct bus_type;
 struct device;
 struct iommu_domain;
+struct notifier_block;
 
 /* iommu fault flags */
 #define IOMMU_FAULT_READ	0x0