On Thu, Jul 23, 2020 at 02:15:07PM +0200, Cornelia Huck wrote: > On Thu, 23 Jul 2020 13:57:08 +0200 > David Hildenbrand <da...@redhat.com> wrote: > > > On 23.07.20 08:33, Cornelia Huck wrote: > > > On Mon, 20 Jul 2020 11:07:51 +0200 > > > David Hildenbrand <da...@redhat.com> wrote: > > > > > >> On 20.07.20 11:03, Michael S. Tsirkin wrote: > > >>> On Mon, Jul 20, 2020 at 10:09:57AM +0200, David Hildenbrand wrote: > > >>>> On 07.07.20 12:54, Cornelia Huck wrote: > > >>>>> As discussed in "virtio-fs: force virtio 1.x usage", it seems like > > >>>>> a good idea to make sure that any new virtio device (which does not > > >>>>> support legacy virtio) is indeed a non-transitional device, just to > > >>>>> catch accidental misconfigurations. We can easily compile a list > > >>>>> of virtio devices with legacy support and have transports verify > > >>>>> in their plugged callbacks that legacy support is off for any device > > >>>>> not in that list. > > >>>>> > > >>>>> Most new virtio devices force non-transitional already, so nothing > > >>>>> changes for them. vhost-user-fs-pci even does not allow to configure > > >>>>> a non-transitional device, so it is fine as well. > > >>>>> > > >>>>> One problematic device, however, is virtio-iommu-pci. It currently > > >>>>> offers both the transitional and the non-transitional variety of the > > >>>>> device, and does not force anything. I'm unsure whether we should > > >>>>> consider transitional virtio-iommu unsupported, or if we should add > > >>>>> some compat handling. (The support for legacy or not generally may > > >>>>> change based upon the bus, IIUC, so I'm unsure how to come up with > > >>>>> something generic.) > > >>>>> > > >>>>> Cornelia Huck (2): > > >>>>> virtio: list legacy-capable devices > > >>>>> virtio: verify that legacy support is not accidentally on > > >>>> > > >>>> I'd squash both patches. Looking at patch #1, I wonder why we don't > > >>>> store that information along with the device implementation? What was > > >>>> the motivation to define this information separately? > > >>> > > >>> Because people seem to cut and paste code, so when one > > >>> enables it in an old device, it gets pasted into a new one. > > >>> With a list in a central place, it's easier to figure out > > >>> what's going on. > > >> > > >> Makes sense, I suggest adding that to the patch description. > > > > > > "The list of devices supporting legacy is supposed to be static. We > > > keep it in a central place to make sure that new devices do not enable > > > legacy by accident." > > > > > > ? > > > > Ack! > > > > > > > >> > > >> Both patches look sane to me (- squashing them). > > >> > > > > > > Patch 1 does not change behaviour, while patch 2 does (for > > > virtio-iommu-pci). Still would like an opinion whether changing the > > > behaviour for virtio-iommu-pci with no compat handling is ok. > > > > > > (I could be persuaded to squash them.) > > > > I'm a friend of introducing helper functions along with code that > > actually uses it. But I agree that the change in behavior might be > > hairy. Maybe we can split that out somehow to give it more attention? > > It should not really be noticeable for anything but virtio-iommu. > > However, I see these are already in a pull request...
Yea, sorry about being hasty. -- MST
