Patchwork [19/61] virtio-net : cleanup : use QOM cast.

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Submitter fred.konrad@greensocs.com
Date Jan. 7, 2013, 6:40 p.m.
Message ID <1357584074-10852-20-git-send-email-fred.konrad@greensocs.com>
Download mbox | patch
Permalink /patch/210104/
State New
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Comments

fred.konrad@greensocs.com - Jan. 7, 2013, 6:40 p.m.
From: KONRAD Frederic <fred.konrad@greensocs.com>

As the virtio-net-pci and virtio-net-s390 are switched to the new API,
we can use QOM casts. This shouldn't been applyied before virtio-net-pci
and virtio-net-s390 refactoring as their VirtIODevice were not a QOM
object.

Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
---
 hw/virtio-net.c | 147 ++++++++++++++++++++++++++++++--------------------------
 hw/virtio-net.h |   2 +-
 2 files changed, 80 insertions(+), 69 deletions(-)
Michael S. Tsirkin - Jan. 7, 2013, 9:16 p.m.
On Mon, Jan 07, 2013 at 07:40:32PM +0100, fred.konrad@greensocs.com wrote:
> @@ -130,7 +124,9 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
>  
>  static void virtio_net_set_link_status(NetClientState *nc)
>  {
> -    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
> +    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
> +    VirtIONet *n = VIRTIO_NET(opaque);
> +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
>      uint16_t old_status = n->status;
>  
>      if (nc->link_down)

I note this adds more pointer chasing due to runtime casts on data path
operations.  Can well be trivial but this really needs to be verified
with a performance test. Was this done? Same comment applies to block.
An alternative is to add _fast casts without runtime checks.
Anthony Liguori - Jan. 7, 2013, 9:17 p.m.
"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Mon, Jan 07, 2013 at 07:40:32PM +0100, fred.konrad@greensocs.com wrote:
>> @@ -130,7 +124,9 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
>>  
>>  static void virtio_net_set_link_status(NetClientState *nc)
>>  {
>> -    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
>> +    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
>> +    VirtIONet *n = VIRTIO_NET(opaque);
>> +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
>>      uint16_t old_status = n->status;
>>  
>>      if (nc->link_down)
>
> I note this adds more pointer chasing due to runtime casts on data path
> operations.  Can well be trivial but this really needs to be verified
> with a performance test. Was this done? Same comment applies to block.
> An alternative is to add _fast casts without runtime checks.

I'm pretty sure other things like the one big global mutex are more
important than the number of pointer dereferences...

Do you have any evidence to suggest that this would be a problem in practice?

Regards,

Anthony Liguori

>
> -- 
> MST
Michael S. Tsirkin - Jan. 7, 2013, 9:33 p.m.
On Mon, Jan 07, 2013 at 03:17:18PM -0600, Anthony Liguori wrote:
> "Michael S. Tsirkin" <mst@redhat.com> writes:
> 
> > On Mon, Jan 07, 2013 at 07:40:32PM +0100, fred.konrad@greensocs.com wrote:
> >> @@ -130,7 +124,9 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
> >>  
> >>  static void virtio_net_set_link_status(NetClientState *nc)
> >>  {
> >> -    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
> >> +    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
> >> +    VirtIONet *n = VIRTIO_NET(opaque);
> >> +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
> >>      uint16_t old_status = n->status;
> >>  
> >>      if (nc->link_down)
> >
> > I note this adds more pointer chasing due to runtime casts on data path
> > operations.  Can well be trivial but this really needs to be verified
> > with a performance test. Was this done? Same comment applies to block.
> > An alternative is to add _fast casts without runtime checks.
> 
> I'm pretty sure other things like the one big global mutex are more
> important than the number of pointer dereferences...

True. But we have plans to fix that, right?

> Do you have any evidence to suggest that this would be a problem in practice?
> 
> Regards,
> 
> Anthony Liguori

No. It's not this change specifically, I'm generally concerned if we let
ourselves bloat datapath in an uncontrolled way, the waste will add up
over time.

> >
> > -- 
> > MST
Anthony Liguori - Jan. 7, 2013, 9:53 p.m.
"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Mon, Jan 07, 2013 at 03:17:18PM -0600, Anthony Liguori wrote:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> 
>> > On Mon, Jan 07, 2013 at 07:40:32PM +0100, fred.konrad@greensocs.com wrote:
>> >> @@ -130,7 +124,9 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
>> >>  
>> >>  static void virtio_net_set_link_status(NetClientState *nc)
>> >>  {
>> >> -    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
>> >> +    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
>> >> +    VirtIONet *n = VIRTIO_NET(opaque);
>> >> +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
>> >>      uint16_t old_status = n->status;
>> >>  
>> >>      if (nc->link_down)
>> >
>> > I note this adds more pointer chasing due to runtime casts on data path
>> > operations.  Can well be trivial but this really needs to be verified
>> > with a performance test. Was this done? Same comment applies to block.
>> > An alternative is to add _fast casts without runtime checks.
>> 
>> I'm pretty sure other things like the one big global mutex are more
>> important than the number of pointer dereferences...
>
> True. But we have plans to fix that, right?
>
>> Do you have any evidence to suggest that this would be a problem in practice?
>> 
>> Regards,
>> 
>> Anthony Liguori
>
> No. It's not this change specifically, I'm generally concerned if we let
> ourselves bloat datapath in an uncontrolled way, the waste will add up
> over time.

I don't think a pointer indirection can be called "bloat[ing] datapath
in an uncontrolled way".

We shouldn't focus on minor things like this, but rather on things like
notification mitigation and lock contention which we know has a direct
impact on performance.

Regards,

Anthony Liguori

>
>> >
>> > -- 
>> > MST

Patch

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 6fe7e58..9cf549a 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -31,17 +31,9 @@ 
  * - we could suppress RX interrupt if we were so inclined.
  */
 
-/*
- * Moving to QOM later in this serie.
- */
-static VirtIONet *to_virtio_net(VirtIODevice *vdev)
-{
-    return (VirtIONet *)vdev;
-}
-
 static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
     struct virtio_net_config netcfg;
 
     stw_p(&netcfg.status, n->status);
@@ -51,7 +43,7 @@  static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
 
 static void virtio_net_set_config(VirtIODevice *vdev, const uint8_t *config)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
     struct virtio_net_config netcfg;
 
     memcpy(&netcfg, config, sizeof(netcfg));
@@ -64,12 +56,14 @@  static void virtio_net_set_config(VirtIODevice *vdev, const uint8_t *config)
 
 static bool virtio_net_started(VirtIONet *n, uint8_t status)
 {
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     return (status & VIRTIO_CONFIG_S_DRIVER_OK) &&
-        (n->status & VIRTIO_NET_S_LINK_UP) && n->vdev.vm_running;
+        (n->status & VIRTIO_NET_S_LINK_UP) && vdev->vm_running;
 }
 
 static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
 {
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     if (!n->nic->nc.peer) {
         return;
     }
@@ -86,10 +80,10 @@  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     }
     if (!n->vhost_started) {
         int r;
-        if (!vhost_net_query(tap_get_vhost_net(n->nic->nc.peer), &n->vdev)) {
+        if (!vhost_net_query(tap_get_vhost_net(n->nic->nc.peer), vdev)) {
             return;
         }
-        r = vhost_net_start(tap_get_vhost_net(n->nic->nc.peer), &n->vdev);
+        r = vhost_net_start(tap_get_vhost_net(n->nic->nc.peer), vdev);
         if (r < 0) {
             error_report("unable to start vhost net: %d: "
                          "falling back on userspace virtio", -r);
@@ -97,14 +91,14 @@  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
             n->vhost_started = 1;
         }
     } else {
-        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), &n->vdev);
+        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), vdev);
         n->vhost_started = 0;
     }
 }
 
 static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     virtio_net_vhost_status(n, status);
 
@@ -130,7 +124,9 @@  static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
 
 static void virtio_net_set_link_status(NetClientState *nc)
 {
-    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
+    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     uint16_t old_status = n->status;
 
     if (nc->link_down)
@@ -139,14 +135,14 @@  static void virtio_net_set_link_status(NetClientState *nc)
         n->status |= VIRTIO_NET_S_LINK_UP;
 
     if (n->status != old_status)
-        virtio_notify_config(&n->vdev);
+        virtio_notify_config(vdev);
 
-    virtio_net_set_status(&n->vdev, n->vdev.status);
+    virtio_net_set_status(vdev, vdev->status);
 }
 
 static void virtio_net_reset(VirtIODevice *vdev)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     /* Reset back to compatibility mode */
     n->promisc = 1;
@@ -207,7 +203,7 @@  static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs)
 
 static uint32_t virtio_net_get_features(VirtIODevice *vdev, uint32_t features)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     features |= (1 << VIRTIO_NET_F_MAC);
 
@@ -255,7 +251,7 @@  static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
 
 static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     virtio_net_set_mrg_rx_bufs(n, !!(features & (1 << VIRTIO_NET_F_MRG_RXBUF)));
 
@@ -386,7 +382,7 @@  static int virtio_net_handle_vlan_table(VirtIONet *n, uint8_t cmd,
 
 static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
     struct virtio_net_ctrl_hdr ctrl;
     virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
     VirtQueueElement elem;
@@ -424,20 +420,22 @@  static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 
 static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     qemu_flush_queued_packets(&n->nic->nc);
 }
 
 static int virtio_net_can_receive(NetClientState *nc)
 {
-    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
-    if (!n->vdev.vm_running) {
+    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    if (!vdev->vm_running) {
         return 0;
     }
 
     if (!virtio_queue_ready(n->rx_vq) ||
-        !(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
+        !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
         return 0;
 
     return 1;
@@ -562,7 +560,9 @@  static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
 
 static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 {
-    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
+    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE];
     struct virtio_net_hdr_mrg_rxbuf mhdr;
     unsigned mhdr_cnt = 0;
@@ -594,7 +594,7 @@  static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
                     "i %zd mergeable %d offset %zd, size %zd, "
                     "guest hdr len %zd, host hdr len %zd guest features 0x%x",
                     i, n->mergeable_rx_bufs, offset, size,
-                    n->guest_hdr_len, n->host_hdr_len, n->vdev.guest_features);
+                    n->guest_hdr_len, n->host_hdr_len, vdev->guest_features);
             exit(1);
         }
 
@@ -651,7 +651,7 @@  static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
     }
 
     virtqueue_flush(n->rx_vq, i);
-    virtio_notify(&n->vdev, n->rx_vq);
+    virtio_notify(vdev, n->rx_vq);
 
     return size;
 }
@@ -660,10 +660,12 @@  static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq);
 
 static void virtio_net_tx_complete(NetClientState *nc, ssize_t len)
 {
-    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
+    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
 
     virtqueue_push(n->tx_vq, &n->async_tx.elem, 0);
-    virtio_notify(&n->vdev, n->tx_vq);
+    virtio_notify(vdev, n->tx_vq);
 
     n->async_tx.elem.out_num = n->async_tx.len = 0;
 
@@ -674,13 +676,14 @@  static void virtio_net_tx_complete(NetClientState *nc, ssize_t len)
 /* TX */
 static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
 {
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     VirtQueueElement elem;
     int32_t num_packets = 0;
-    if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+    if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return num_packets;
     }
 
-    assert(n->vdev.vm_running);
+    assert(vdev->vm_running);
 
     if (n->async_tx.elem.out_num) {
         virtio_queue_set_notification(n->tx_vq, 0);
@@ -729,7 +732,7 @@  static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
         len += ret;
 
         virtqueue_push(vq, &elem, 0);
-        virtio_notify(&n->vdev, vq);
+        virtio_notify(vdev, vq);
 
         if (++num_packets >= n->tx_burst) {
             break;
@@ -740,10 +743,10 @@  static int32_t virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
 
 static void virtio_net_handle_tx_timer(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     /* This happens when device was stopped but VCPU wasn't. */
-    if (!n->vdev.vm_running) {
+    if (!vdev->vm_running) {
         n->tx_waiting = 1;
         return;
     }
@@ -763,14 +766,14 @@  static void virtio_net_handle_tx_timer(VirtIODevice *vdev, VirtQueue *vq)
 
 static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIONet *n = to_virtio_net(vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     if (unlikely(n->tx_waiting)) {
         return;
     }
     n->tx_waiting = 1;
     /* This happens when device was stopped but VCPU wasn't. */
-    if (!n->vdev.vm_running) {
+    if (!vdev->vm_running) {
         return;
     }
     virtio_queue_set_notification(vq, 0);
@@ -779,14 +782,16 @@  static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
 
 static void virtio_net_tx_timer(void *opaque)
 {
-    VirtIONet *n = opaque;
-    assert(n->vdev.vm_running);
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    assert(vdev->vm_running);
 
     n->tx_waiting = 0;
 
     /* Just in case the driver is not ready on more */
-    if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
+    if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return;
+    }
 
     virtio_queue_set_notification(n->tx_vq, 1);
     virtio_net_flush_tx(n, n->tx_vq);
@@ -794,16 +799,18 @@  static void virtio_net_tx_timer(void *opaque)
 
 static void virtio_net_tx_bh(void *opaque)
 {
-    VirtIONet *n = opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     int32_t ret;
 
-    assert(n->vdev.vm_running);
+    assert(vdev->vm_running);
 
     n->tx_waiting = 0;
 
     /* Just in case the driver is not ready on more */
-    if (unlikely(!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)))
+    if (unlikely(!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))) {
         return;
+    }
 
     ret = virtio_net_flush_tx(n, n->tx_vq);
     if (ret == -EBUSY) {
@@ -831,12 +838,13 @@  static void virtio_net_tx_bh(void *opaque)
 
 static void virtio_net_save(QEMUFile *f, void *opaque)
 {
-    VirtIONet *n = opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
 
     /* At this point, backend must be stopped, otherwise
      * it might keep writing to memory. */
     assert(!n->vhost_started);
-    virtio_save(&n->vdev, f);
+    virtio_save(vdev, f);
 
     qemu_put_buffer(f, n->mac, ETH_ALEN);
     qemu_put_be32(f, n->tx_waiting);
@@ -859,14 +867,15 @@  static void virtio_net_save(QEMUFile *f, void *opaque)
 
 static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 {
-    VirtIONet *n = opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
     int i;
     int ret;
 
     if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
         return -EINVAL;
 
-    ret = virtio_load(&n->vdev, f);
+    ret = virtio_load(vdev, f);
     if (ret) {
         return ret;
     }
@@ -915,11 +924,11 @@  static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 
         if (n->has_vnet_hdr) {
             tap_set_offload(n->nic->nc.peer,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_UFO)  & 1);
+                    (vdev->guest_features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
+                    (vdev->guest_features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
+                    (vdev->guest_features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
+                    (vdev->guest_features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
+                    (vdev->guest_features >> VIRTIO_NET_F_GUEST_UFO)  & 1);
         }
     }
 
@@ -959,7 +968,8 @@  static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 
 static void virtio_net_cleanup(NetClientState *nc)
 {
-    VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
+    void *opaque = DO_UPCAST(NICState, nc, nc)->opaque;
+    VirtIONet *n = VIRTIO_NET(opaque);
 
     n->nic = NULL;
 }
@@ -985,6 +995,7 @@  static VirtIODevice *virtio_net_common_init(DeviceState *dev, NICConf *conf,
                                            virtio_net_conf *net, VirtIONet **pn)
 {
     VirtIONet *n = *pn;
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 
     /*
      * We have two cases here : the old virtio-net-pci device, and the
@@ -1001,14 +1012,14 @@  static VirtIODevice *virtio_net_common_init(DeviceState *dev, NICConf *conf,
                                       sizeof(struct virtio_net_config));
     }
 
-    n->vdev.get_config = virtio_net_get_config;
-    n->vdev.set_config = virtio_net_set_config;
-    n->vdev.get_features = virtio_net_get_features;
-    n->vdev.set_features = virtio_net_set_features;
-    n->vdev.bad_features = virtio_net_bad_features;
-    n->vdev.reset = virtio_net_reset;
-    n->vdev.set_status = virtio_net_set_status;
-    n->rx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_rx);
+    vdev->get_config = virtio_net_get_config;
+    vdev->set_config = virtio_net_set_config;
+    vdev->get_features = virtio_net_get_features;
+    vdev->set_features = virtio_net_set_features;
+    vdev->bad_features = virtio_net_bad_features;
+    vdev->reset = virtio_net_reset;
+    vdev->set_status = virtio_net_set_status;
+    n->rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
 
     if (net->tx && strcmp(net->tx, "timer") && strcmp(net->tx, "bh")) {
         error_report("virtio-net: "
@@ -1018,14 +1029,14 @@  static VirtIODevice *virtio_net_common_init(DeviceState *dev, NICConf *conf,
     }
 
     if (net->tx && !strcmp(net->tx, "timer")) {
-        n->tx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_tx_timer);
+        n->tx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer);
         n->tx_timer = qemu_new_timer_ns(vm_clock, virtio_net_tx_timer, n);
         n->tx_timeout = net->txtimer;
     } else {
-        n->tx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_tx_bh);
+        n->tx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh);
         n->tx_bh = qemu_bh_new(virtio_net_tx_bh, n);
     }
-    n->ctrl_vq = virtio_add_queue(&n->vdev, 64, virtio_net_handle_ctrl);
+    n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
     qemu_macaddr_default_if_unset(&conf->macaddr);
     memcpy(&n->mac[0], &conf->macaddr, sizeof(n->mac));
     n->status = VIRTIO_NET_S_LINK_UP;
@@ -1056,7 +1067,7 @@  static VirtIODevice *virtio_net_common_init(DeviceState *dev, NICConf *conf,
 
     add_boot_device_path(conf->bootindex, dev, "/ethernet-phy@0");
 
-    return &n->vdev;
+    return vdev;
 }
 
 VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
@@ -1068,7 +1079,7 @@  VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
 
 void virtio_net_exit(VirtIODevice *vdev)
 {
-    VirtIONet *n = DO_UPCAST(VirtIONet, vdev, vdev);
+    VirtIONet *n = VIRTIO_NET(vdev);
 
     /* This will stop vhost backend if appropriate. */
     virtio_net_set_status(vdev, 0);
@@ -1088,7 +1099,7 @@  void virtio_net_exit(VirtIODevice *vdev)
     }
 
     qemu_del_net_client(&n->nic->nc);
-    virtio_cleanup(&n->vdev);
+    virtio_cleanup(vdev);
 }
 
 static int virtio_net_device_init(VirtIODevice *vdev)
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index 2bdc8fd..3246a28 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -130,7 +130,7 @@  struct virtio_net_ctrl_mac {
 };
 
 typedef struct VirtIONet {
-    VirtIODevice vdev;
+    VirtIODevice parent_obj;
     uint8_t mac[ETH_ALEN];
     uint16_t status;
     VirtQueue *rx_vq;