Re: [Qemu-devel] [RFC] virtio-bus: Plug devices after features are negotiated

[Maxime Coquelin]

On 09/09/2016 05:39 PM, Michael S. Tsirkin wrote:
> On Fri, Sep 09, 2016 at 04:14:59PM +0200, Maxime Coquelin wrote:
> > > Currently, devices are plugged before features are negotiated.
> > > If the backend doesn't support VIRTIO_F_VERSION_1, the transport
> > > need to rewind some settings.
> > >
> > > This is the case for both PCI and CCW.
> > > For CCW, a post_plugged callback had been introduced, where
> > > max_rev field is just updated if VIRTIO_F_VERSION_1 is not
> > > supported by the backend.
> > > For PCI, implementing the post_plugged would be much more
> > > complicated, so the current fix consists in checking whether
> > > the backend supports VIRTIO_F_VERSION_1 in the backend.
> > >
> > > This patch propose to replace existing solutions with a common
> > > approach by negociating features before ->device_plugged() is
> > > called. A pre_plugged callback is introduced so that the
> > > transports can set their supported features.
> > >
> > > Cc: Cornelia Huck <address@hidden>
> > > Cc: Marcel Apfelbaum <address@hidden>
> > > Cc: Michael S. Tsirkin <address@hidden>
> > > Signed-off-by: Maxime Coquelin <address@hidden>
>
> Acked-by: Michael S. Tsirkin <address@hidden>
>
> Looks good - can you pls test and post a non-RFC?

Do you mean having this also in stable, or keeping
it based on top of former pci-only patch?

I already tested it for PCI, but cannot test it for CCW.

Thanks,
Maxime