diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 9f1753f5cf..ad8226e240 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -114,6 +114,11 @@ void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
     }
 }
 
+DeviceState *qdev_get_bus_device(const DeviceState *dev)
+{
+    return dev->parent_bus ? dev->parent_bus->parent : NULL;
+}
+
 /* Create a new device.  This only initializes the device state
    structure and allows properties to be set.  The device still needs
    to be realized.  See qdev-core.h.  */
diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index 0592818447..63a6c07406 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -125,9 +125,11 @@ static char *pxb_host_ofw_unit_address(const SysBusDevice *dev)
     assert(position >= 0);
 
     pxb_dev_base = DEVICE(pxb_dev);
-    main_host = PCI_HOST_BRIDGE(pxb_dev_base->parent_bus->parent);
+    main_host = PCI_HOST_BRIDGE(qdev_get_bus_device(pxb_dev_base));
     main_host_sbd = SYS_BUS_DEVICE(main_host);
 
+    g_assert(main_host);
+
     if (main_host_sbd->num_mmio > 0) {
         return g_strdup_printf(TARGET_FMT_plx ",%x",
                                main_host_sbd->mmio[0].addr, position + 1);
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index ad0e7f6d88..3d9497882b 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1558,10 +1558,12 @@ void scsi_device_purge_requests(SCSIDevice *sdev, SCSISense sense)
 static char *scsibus_get_dev_path(DeviceState *dev)
 {
     SCSIDevice *d = SCSI_DEVICE(dev);
-    DeviceState *hba = dev->parent_bus->parent;
+    DeviceState *hba = qdev_get_bus_device(dev);
     char *id;
     char *path;
 
+    g_assert(hba);
+
     id = qdev_get_dev_path(hba);
     if (id) {
         path = g_strdup_printf("%s/%d:%d:%d", id, d->channel, d->id, d->lun);
diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index a6522f5429..26bf794315 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -587,9 +587,11 @@ static void usb_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 static char *usb_get_dev_path(DeviceState *qdev)
 {
     USBDevice *dev = USB_DEVICE(qdev);
-    DeviceState *hcd = qdev->parent_bus->parent;
+    DeviceState *hcd = qdev_get_bus_device(qdev);
     char *id = NULL;
 
+    g_assert(hcd);
+
     if (dev->flags & (1 << USB_DEV_FLAG_FULL_PATH)) {
         id = qdev_get_dev_path(hcd);
     }
diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
index 4568db2568..fbb3599ddd 100644
--- a/hw/usb/dev-smartcard-reader.c
+++ b/hw/usb/dev-smartcard-reader.c
@@ -1185,10 +1185,12 @@ void ccid_card_send_apdu_to_guest(CCIDCardState *card,
                                   uint8_t *apdu, uint32_t len)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
     Answer *answer;
 
+    g_assert(dev);
+
     if (!ccid_has_pending_answers(s)) {
         DPRINTF(s, 1, "CCID ERROR: got an APDU without pending answers\n");
         return;
@@ -1208,9 +1210,11 @@ void ccid_card_send_apdu_to_guest(CCIDCardState *card,
 void ccid_card_card_removed(CCIDCardState *card)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
 
+    g_assert(dev);
+
     ccid_on_slot_change(s, false);
     ccid_flush_pending_answers(s);
     ccid_reset(s);
@@ -1219,9 +1223,11 @@ void ccid_card_card_removed(CCIDCardState *card)
 int ccid_card_ccid_attach(CCIDCardState *card)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
 
+    g_assert(dev);
+
     DPRINTF(s, 1, "CCID Attach\n");
     return 0;
 }
@@ -1229,9 +1235,11 @@ int ccid_card_ccid_attach(CCIDCardState *card)
 void ccid_card_ccid_detach(CCIDCardState *card)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
 
+    g_assert(dev);
+
     DPRINTF(s, 1, "CCID Detach\n");
     if (ccid_card_inserted(s)) {
         ccid_on_slot_change(s, false);
@@ -1242,9 +1250,11 @@ void ccid_card_ccid_detach(CCIDCardState *card)
 void ccid_card_card_error(CCIDCardState *card, uint64_t error)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
 
+    g_assert(dev);
+
     s->bmCommandStatus = COMMAND_STATUS_FAILED;
     s->last_answer_error = error;
     DPRINTF(s, 1, "VSC_Error: %" PRIX64 "\n", s->last_answer_error);
@@ -1261,9 +1271,11 @@ void ccid_card_card_error(CCIDCardState *card, uint64_t error)
 void ccid_card_card_inserted(CCIDCardState *card)
 {
     DeviceState *qdev = DEVICE(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
 
+    g_assert(dev);
+
     s->bmCommandStatus = COMMAND_STATUS_NO_ERROR;
     ccid_flush_pending_answers(s);
     ccid_on_slot_change(s, true);
@@ -1273,10 +1285,12 @@ static void ccid_card_unrealize(DeviceState *qdev, Error **errp)
 {
     CCIDCardState *card = CCID_CARD(qdev);
     CCIDCardClass *cc = CCID_CARD_GET_CLASS(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
     Error *local_err = NULL;
 
+    g_assert(dev);
+
     if (ccid_card_inserted(s)) {
         ccid_card_card_removed(card);
     }
@@ -1294,10 +1308,12 @@ static void ccid_card_realize(DeviceState *qdev, Error **errp)
 {
     CCIDCardState *card = CCID_CARD(qdev);
     CCIDCardClass *cc = CCID_CARD_GET_CLASS(card);
-    USBDevice *dev = USB_DEVICE(qdev->parent_bus->parent);
+    USBDevice *dev = USB_DEVICE(qdev_get_bus_device(qdev));
     USBCCIDState *s = USB_CCID_DEV(dev);
     Error *local_err = NULL;
 
+    g_assert(dev);
+
     if (card->slot != 0) {
         error_setg(errp, "usb-ccid supports one slot, can't add %d",
                    card->slot);
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index f723b9f631..8ce9269aab 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1317,9 +1317,21 @@ static uint64_t virtio_pci_notify_read(void *opaque, hwaddr addr,
 static void virtio_pci_notify_write(void *opaque, hwaddr addr,
                                     uint64_t val, unsigned size)
 {
+    DeviceState *dev = DEVICE(opaque);
     VirtIODevice *vdev = opaque;
-    VirtIOPCIProxy *proxy = VIRTIO_PCI(DEVICE(vdev)->parent_bus->parent);
-    unsigned queue = addr / virtio_pci_queue_mem_mult(proxy);
+    VirtIOPCIProxy *proxy = VIRTIO_PCI(qdev_get_bus_device(dev));
+    unsigned queue;
+
+    /*
+     * During unplug virtio device may have
+     * already been disconnected from the bus
+     */
+    if (!proxy) {
+        warn_report("Device %s doesn't have parent bus", vdev->name);
+        return;
+    }
+
+    queue = addr / virtio_pci_queue_mem_mult(proxy);
 
     if (queue < VIRTIO_QUEUE_MAX) {
         virtio_queue_notify(vdev, queue);
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 1518495b1e..05d68f0f1a 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -452,6 +452,8 @@ Object *qdev_get_machine(void);
 /* FIXME: make this a link<> */
 void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
 
+DeviceState *qdev_get_bus_device(const DeviceState *dev);
+
 extern bool qdev_hotplug;
 extern bool qdev_hot_removed;
 
