Re: [PATCH 1/3] vhost-vsock-pci: force virtio version 1

[Cornelia Huck]

On Wed, 19 Aug 2020 14:09:10 +0200
Stefano Garzarella <sgarzare@redhat.com> wrote:

> On Wed, Aug 19, 2020 at 01:55:42PM +0200, Cornelia Huck wrote:
> > On Wed, 19 Aug 2020 12:51:54 +0200
> > Stefano Garzarella <sgarzare@redhat.com> wrote:
> >   
> > > Commit 9b3a35ec82 ("virtio: verify that legacy support is not
> > > accidentally on") added a safety checks that requires to set  
> > 
> > Nit: s/checks/check/ (also in patch 2)  
> 
> I'll fix.
> 
> >   
> > > 'disable-legacy=on' on vhost-vsock-pci device:
> > > 
> > >     $ ./qemu-system-x86_64 ... -device vhost-vsock-pci,guest-cid=5
> > >         qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=5:
> > >         device is modern-only, use disable-legacy=on
> > > 
> > > virtio-vsock was introduced after the release of VIRTIO 1.0
> > > specifications, so it should be 'modern-only'.
> > > In addition Cornelia verified that forcing a legacy mode on
> > > vhost-vsock-pci device using x86-64 host and s390x guest, so with
> > > different endianness, produces strange behaviours.
> > > 
> > > This patch forces virtio version 1 and remove 'transitional_name'
> > > properties removing the need to specify 'disable-legacy=on' on  
> > 
> > "removes the 'transitional_name' property" ?  
> 
> It is better, I'll fix.
> 
> > 
> > (Unless you want to merge with patch 2, which might make sense.)  
> 
> I left seprated because vhost-user-vsock-pci was introduced in QEMU 5.1,
> so I wanted to make it easier to backport on others stable branches.
> (I'm not sure if we continue to support 4.2).
> 
> Does it make sense to keep them separated?

Yes, indeed, it makes sense for stable backporting purposes.