Re: [PATCH] virtio-pmem-pci: force virtio version 1

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 25 Sep 2020 13:49:05 +0200
Pankaj Gupta <pankaj.gupta.linux@gmail.com> wrote:

> >  
> > >  Qemu fails with below error when trying to run with virtio pmem:
> > >
> > >  (qemu) qemu-system-x86_64: -device virtio-pmem-pci,memdev=mem1,id=nv1:
> > >   device is modern-only, use disable-legacy=on  
> >
> > Oh, another one :(  
> :)
> >  
> > >
> > >  This patch fixes this by forcing virtio 1 with virtio-pmem.
> > >
> > > fixes: adf0748a49 ("virtio-pci: Proxy for virtio-pmem")
> > > Signed-off-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
> > > ---
> > >  hw/virtio/virtio-pmem-pci.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/hw/virtio/virtio-pmem-pci.c b/hw/virtio/virtio-pmem-pci.c
> > > index 21a457d151..2b2a0b1eae 100644
> > > --- a/hw/virtio/virtio-pmem-pci.c
> > > +++ b/hw/virtio/virtio-pmem-pci.c
> > > @@ -22,6 +22,7 @@ static void virtio_pmem_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
> > >      VirtIOPMEMPCI *pmem_pci = VIRTIO_PMEM_PCI(vpci_dev);
> > >      DeviceState *vdev = DEVICE(&pmem_pci->vdev);
> > >
> > > +    virtio_pci_force_virtio_1(vpci_dev);
> > >      qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
> > >  }
> > >  
> >
> > The alternative would be to force virtio 1 only for 5.1 and later (see
> > https://lore.kernel.org/qemu-devel/20200921122506.82515-1-sgarzare@redhat.com/).  
> 
> Thanks for sharing this. It's still good to mark virtio pmem as a
> modern virtio device.

If you don't really need to care about compat handling, forcing virtio
1 is fine.

Acked-by: Cornelia Huck <cohuck@redhat.com>