Index: head/sys/amd64/vmm/io/iommu.c
===================================================================
--- head/sys/amd64/vmm/io/iommu.c
+++ head/sys/amd64/vmm/io/iommu.c
@@ -174,6 +174,7 @@
 {
 	int error, bus, slot, func;
 	vm_paddr_t maxaddr;
+	devclass_t dc;
 	device_t dev;
 
 	if (!iommu_enable)
@@ -214,6 +215,7 @@
 	add_tag = EVENTHANDLER_REGISTER(pci_add_device, iommu_pci_add, NULL, 0);
 	delete_tag = EVENTHANDLER_REGISTER(pci_delete_device, iommu_pci_delete,
 	    NULL, 0);
+	dc = devclass_find("ppt");
 	for (bus = 0; bus <= PCI_BUSMAX; bus++) {
 		for (slot = 0; slot <= PCI_SLOTMAX; slot++) {
 			for (func = 0; func <= PCI_FUNCMAX; func++) {
@@ -221,7 +223,15 @@
 				if (dev == NULL)
 					continue;
 
-				/* Everything belongs to the host domain. */
+				/* Skip passthrough devices. */
+				if (dc != NULL &&
+				    device_get_devclass(dev) == dc)
+					continue;
+
+				/*
+				 * Everything else belongs to the host
+				 * domain.
+				 */
 				iommu_add_device(host_domain,
 				    pci_get_rid(dev));
 			}
Index: head/sys/amd64/vmm/io/ppt.c
===================================================================
--- head/sys/amd64/vmm/io/ppt.c
+++ head/sys/amd64/vmm/io/ppt.c
@@ -154,6 +154,7 @@
 
 	ppt = device_get_softc(dev);
 
+	iommu_remove_device(iommu_host_domain(), pci_get_rid(dev));
 	num_pptdevs++;
 	TAILQ_INSERT_TAIL(&pptdev_list, ppt, next);
 	ppt->dev = dev;
@@ -175,6 +176,8 @@
 		return (EBUSY);
 	num_pptdevs--;
 	TAILQ_REMOVE(&pptdev_list, ppt, next);
+	pci_disable_busmaster(dev);
+	iommu_add_device(iommu_host_domain(), pci_get_rid(dev));
 
 	return (0);
 }
@@ -368,7 +371,6 @@
 		    true);
 		pci_restore_state(ppt->dev);
 		ppt->vm = vm;
-		iommu_remove_device(iommu_host_domain(), pci_get_rid(ppt->dev));
 		iommu_add_device(vm_iommu_domain(vm), pci_get_rid(ppt->dev));
 		return (0);
 	}
@@ -397,7 +399,6 @@
 		ppt_teardown_msi(ppt);
 		ppt_teardown_msix(ppt);
 		iommu_remove_device(vm_iommu_domain(vm), pci_get_rid(ppt->dev));
-		iommu_add_device(iommu_host_domain(), pci_get_rid(ppt->dev));
 		ppt->vm = NULL;
 		return (0);
 	}