diff --git a/devicemodel/core/main.c b/devicemodel/core/main.c
index 6963a0271..a850b06d6 100644
--- a/devicemodel/core/main.c
+++ b/devicemodel/core/main.c
@@ -66,6 +66,7 @@
 #include "virtio.h"
 #include "pm_vuart.h"
 #include "log.h"
+#include "pci_util.h"
 
 #define GUEST_NIO_PORT		0x488	/* guest upcalls via i/o port */
 
@@ -1122,5 +1123,6 @@ fail:
 create_fail:
 	uninit_hugetlb();
 	deinit_loggers();
+	clean_pci_cache();
 	exit(ret);
 }
diff --git a/devicemodel/hw/pci/pci_util.c b/devicemodel/hw/pci/pci_util.c
index 4dd588a0f..9055cb271 100644
--- a/devicemodel/hw/pci/pci_util.c
+++ b/devicemodel/hw/pci/pci_util.c
@@ -18,22 +18,6 @@
 
 #define MAX_LEN			(PCI_BUSMAX + 1)
 
-struct pci_device_info {
-	bool is_bridge;
-	int primary_bus;
-	int secondary_bus;
-	int subordinate_bus;
-	uint16_t bdf;
-	struct pci_device_info *parent;  /* pointer to its parent bridge */
-	struct pci_device_info *clist;  /* children list */
-
-	/* cache of all pci devices
-	 * FIXME: remove PCI_DEVICE_Q.  To cleanup pci device cache:
-	 * remove children, then remove parents
-	 */
-	TAILQ_ENTRY(pci_device_info) PCI_DEVICE_Q;
-};
-
 TAILQ_HEAD(ALL_PCI_DEVICES, pci_device_info);
 static struct ALL_PCI_DEVICES pci_device_q;
 
@@ -196,6 +180,9 @@ int scan_pci(void)
 	struct pci_device *dev;
 	int i;
 
+	if (pci_scanned)
+		return 0;
+
 	TAILQ_INIT(&pci_device_q);
 
 	pci_scanned = 1;
@@ -243,7 +230,11 @@ int scan_pci(void)
 
 done:
 	if (error < 0)
+	{
+		pr_err("%s: failed to build pci hierarchy.\n", __func__);
 		clean_pci_cache();
+		pci_scanned = false;
+	}
 
 	pci_iterator_destroy(iter);
 
diff --git a/devicemodel/hw/pci/ptm.c b/devicemodel/hw/pci/ptm.c
index d03ebad67..5f481d0cf 100644
--- a/devicemodel/hw/pci/ptm.c
+++ b/devicemodel/hw/pci/ptm.c
@@ -106,10 +106,10 @@ add_vroot_port(struct vmctx *ctx, struct passthru_dev *ptdev, struct pci_device
 int ptm_probe(struct vmctx *ctx, struct passthru_dev *ptdev, int *vrp_sec_bus)
 {
 	int error = 0;
-	int pos, pcie_type, cap, rootport_ptm_offset, device_ptm_offset;
+	int pos, pcie_type, cap, rp_ptm_offset, device_ptm_offset;
 	struct pci_device *phys_dev = ptdev->phys_dev;
-	//struct pci_bridge_info bridge_info = {};
-	struct pci_device *root_port;
+	struct pci_device *rp;
+	struct pci_device_info rp_info = {};
 
 	*vrp_sec_bus = 0;
 
@@ -146,23 +146,37 @@ int ptm_probe(struct vmctx *ctx, struct passthru_dev *ptdev, int *vrp_sec_bus)
 			return -EINVAL;
 		}
 
-		root_port = pci_find_root_port(phys_dev);
-		if (root_port == NULL) {
+		rp = pci_find_root_port(phys_dev);
+		if (rp == NULL) {
 			pr_err("%s Error: Cannot find root port of %x:%x.%x.\n", __func__,
 					phys_dev->bus, phys_dev->dev, phys_dev->func);
 			return -ENODEV;
 		}
 
-		cap = get_ptm_cap(root_port, &rootport_ptm_offset);
+		cap = get_ptm_cap(rp, &rp_ptm_offset);
 		if (!(cap & PCIM_PTM_CAP_ROOT)) {
 			pr_err("%s Error: root port %x:%x.%x of %x:%x.%x is not PTM root.\n",
-				__func__, root_port->bus, root_port->dev,
-				root_port->func, phys_dev->bus, phys_dev->dev, phys_dev->func);
+				__func__, rp->bus, rp->dev,
+				rp->func, phys_dev->bus, phys_dev->dev, phys_dev->func);
+			return -EINVAL;
+		}
+
+		/* check whether more than one devices are connected to the root port.
+		 * if more than one devices are connected to the root port, we flag
+		 * this as error and won't enable PTM.  We do this just because we
+		 * don't have this hw configuration and won't be able totest this case.
+		 */
+		error = pci_device_get_bridge_buses(rp, &(rp_info.primary_bus),
+					&(rp_info.secondary_bus), &(rp_info.subordinate_bus));
+
+		if (error || (get_device_count_on_bridge(&rp_info) != 1)) {
+			pr_err("%s Error: Failed to enable PTM on root port [%x:%x.%x] that has multiple children.\n",
+					__func__, rp->bus, rp->dev, rp->func);
 			return -EINVAL;
 		}
 
 		// add virtual root port
-		*vrp_sec_bus = add_vroot_port(ctx, ptdev, root_port, rootport_ptm_offset);
+		*vrp_sec_bus = add_vroot_port(ctx, ptdev, rp, rp_ptm_offset);
 
 	} else if (pcie_type == PCIEM_TYPE_ROOT_INT_EP) {
 		// No need to emulate root port if ptm requestor is RCIE
diff --git a/devicemodel/include/pci_util.h b/devicemodel/include/pci_util.h
index 9be322e45..524459b97 100644
--- a/devicemodel/include/pci_util.h
+++ b/devicemodel/include/pci_util.h
@@ -11,7 +11,21 @@
 #include <stdbool.h>
 #include "pciaccess.h"
 
-struct pci_device_info;
+struct pci_device_info {
+	bool is_bridge;
+	int primary_bus;
+	int secondary_bus;
+	int subordinate_bus;
+	uint16_t bdf;
+	struct pci_device_info *parent;  /* pointer to its parent bridge */
+	struct pci_device_info *clist;  /* children list */
+
+	/* cache of all pci devices
+	 * FIXME: remove PCI_DEVICE_Q.  To cleanup pci device cache:
+	 * remove children, then remove parents
+	 */
+	TAILQ_ENTRY(pci_device_info) PCI_DEVICE_Q;
+};
 
 int pci_find_cap(struct pci_device *pdev, const int cap_id);
 int pci_find_ext_cap(struct pci_device *pdev, int cap_id);