Linux Virtualization - Nov 2011 - [PATCH v2 09/11] virtio: net: Add freeze, restore handlers to support S4

On (Sun) 02 Oct 2011 [11:33:26], Michael S. Tsirkin
wrote:
> On Thu, Sep 29, 2011 at 09:19:40PM +0530, Amit Shah wrote:
> > Remove all the vqs on hibernation and re-create them after restoring
> > from a hibernated image.  This keeps networking working across
> > hibernation.
> > 
> > Signed-off-by: Amit Shah <amit.shah at redhat.com>
> > ---
> >  drivers/net/virtio_net.c |   28 ++++++++++++++++++++++++++++
> >  1 files changed, 28 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index dcd4b01..8b9ed43 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1131,6 +1131,30 @@ static void __devexit virtnet_remove(struct
virtio_device *vdev)
> >  	free_netdev(vi->dev);
> >  }
> >  
> > +#ifdef CONFIG_PM
> > +static int virtnet_freeze(struct virtio_device *vdev)
> > +{
> > +	struct virtnet_info *vi = vdev->priv;
> 
> I'm guessing we need to do something like netif_device_detach here,
> otherwise guest might be in the process of using the vq for transmit at
> this point.
Done.
> I think we also must make sure NAPI RX handler is not in progress.
How to do that?  napi_disable() / napi_enable() doesn't seem right
(and it doesn't work, too).  pci_disable_device() in the suspend
routine may work?
> We also might need to mask interrupts from the device
> to prevent TX or RX from getting rescheduled?
pci_disable_device() will help this too, right?

		Amit

On Tue, Nov 15, 2011 at 05:59:36PM +0530, Amit Shah
wrote:
> On (Sun) 02 Oct 2011 [11:33:26], Michael S. Tsirkin wrote:
> > On Thu, Sep 29, 2011 at 09:19:40PM +0530, Amit Shah wrote:
> > > Remove all the vqs on hibernation and re-create them after
restoring
> > > from a hibernated image.  This keeps networking working across
> > > hibernation.
> > > 
> > > Signed-off-by: Amit Shah <amit.shah at redhat.com>
> > > ---
> > >  drivers/net/virtio_net.c |   28 ++++++++++++++++++++++++++++
> > >  1 files changed, 28 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index dcd4b01..8b9ed43 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -1131,6 +1131,30 @@ static void __devexit
virtnet_remove(struct virtio_device *vdev)
> > >  	free_netdev(vi->dev);
> > >  }
> > >  
> > > +#ifdef CONFIG_PM
> > > +static int virtnet_freeze(struct virtio_device *vdev)
> > > +{
> > > +	struct virtnet_info *vi = vdev->priv;
> > 
> > I'm guessing we need to do something like netif_device_detach
here,
> > otherwise guest might be in the process of using the vq for transmit
at
> > this point.
> 
> Done.
> 
> > I think we also must make sure NAPI RX handler is not in progress.
> 
> How to do that?  napi_disable() / napi_enable() doesn't seem right
> (and it doesn't work, too).  pci_disable_device() in the suspend
> routine may work?
> 
> > We also might need to mask interrupts from the device
> > to prevent TX or RX from getting rescheduled?
> 
> pci_disable_device() will help this too, right?
> 
> 		Amit
No, why would it help?

-- 
MST