Re: [Qemu-devel] [PATCH v4 0/2] virtio: Move host features to backends

[Michael S. Tsirkin]

On Tue, Apr 28, 2015 at 02:06:35PM +0100, Peter Maydell wrote:
> On 28 April 2015 at 12:51,  <address@hidden> wrote:
> > From: Shannon Zhao <address@hidden>
> >
> > The reason to do this is that the virtio-net-device can't expose host
> > features to guest while using virtio-mmio. So the performance is low.
> >
> > The virtio-*-pci, virtio-*-s390, and virtio-*-ccw already have the
> > ability to forward property accesses to the backend child, by calling
> > *_virtio_*_instance_init -> qdev_alias_all_properties. So if we move the
> > host features to backends, it doesn't break the backwards compatibility
> > for virtio-*-pci, virtio-*-s390, and virtio-*-ccw.
> >
> > Here we move the host features to backends, involving
> > DEFINE_VIRTIO_NET_FEATURES, DEFINE_VIRTIO_SCSI_FEATURES. So the
> > virtio-mmio devices could have the host freatures, and this has a great
> > performance improvement to virtio-mmio, especially to virtio-net-device.
> 
> Reviewed-by: Peter Maydell <address@hidden>
> 
> (but not tested :-))
> 
> thanks
> -- PMM

The patches look correct to me too, but I want s390
cleaned up so it does not include COMMON_FEATURES
in 100 places, and I prefer merging it all together.

-- 
MST