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

[Eric Blake]

On 09/10/2016 03:23 AM, 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 CCW, for which 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 it needs to know whether the backend supports
> VIRTIO_F_VERSION_1 at plug time.
> 
> Currently, nothing is done for PCI. Modern capabilitities get

s/capabilitities/capabilities/

> exposed to the guest even if VIRTIO_F_VERSION_1 is not supported
> by the backend, which confuses the guest.
> 
> This patch proposes to replace existing post_plugged solution
> with an approach that fits with both transports.
> Features negociation is performed before ->device_plugged() call.

s/negociation/negotiation/

> 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: address@hidden
> Acked-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Maxime Coquelin <address@hidden>
> ---

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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