* Michael S. Tsirkin (m...@redhat.com) wrote: > On Mon, Jun 29, 2020 at 12:27:58PM +0200, Cornelia Huck wrote: > > virtio-fs devices are only specified for virtio-1, so it is unclear > > how a legacy or transitional device should behave. > > > > Signed-off-by: Cornelia Huck <coh...@redhat.com> > > --- > > > > Forcing off legacy now (after the virtio-fs device has already been > > available) may have unintended consequences, therefore RFC. > > > > By default, a virtio-pci device uses 'AUTO' for disable_legacy, which > > will resolve to different values based upon which bus the device has > > been plugged. Therefore, forcing disable_legacy may result in the same > > device or a quite different one. > > > > Even though pre-virtio-1 behaviour of virtio-fs devices is simply not > > specified, toggling disable_legacy will have implications for the BAR > > layout, IIRC, and therefore a guest might end up getting a different > > device, even if it always used it with virtio-1 anyway. > > > > Not sure what the best way to solve this problem is. Adding a compat > > property for disable_legacy=AUTO may be the right thing to do, but I'm > > not quite clear if there are any further implications here. > > Well I notice that this device is not migrateable. > So I think that we can just switch it over and be done with it.
Yes, I think I'm OK with that - although you could add the compat flag in the machine type I guess. Dave > > > Whatever we do here, we should make sure that the ccw incarnation of > > this device indeed forces virtio-1. > > I agree. I notice that the API virtio_pci_force_virtio_1 turned out > to be too fragile. I propose that instead we have a whitelist of > devices which can be legacy or transitional. Force rest to modern. > > > > --- > > hw/virtio/vhost-user-fs-pci.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/virtio/vhost-user-fs-pci.c b/hw/virtio/vhost-user-fs-pci.c > > index e11c889d82b3..244205edf765 100644 > > --- a/hw/virtio/vhost-user-fs-pci.c > > +++ b/hw/virtio/vhost-user-fs-pci.c > > @@ -44,6 +44,7 @@ static void vhost_user_fs_pci_realize(VirtIOPCIProxy > > *vpci_dev, Error **errp) > > vpci_dev->nvectors = dev->vdev.conf.num_request_queues + 2; > > } > > > > + virtio_pci_force_virtio_1(vpci_dev); > > qdev_realize(vdev, BUS(&vpci_dev->bus), errp); > > } > > > > -- > > 2.25.4 > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
