On Thu, Jan 03, 2019 at 11:23:45PM -0500, Michael S. Tsirkin wrote:
> On Fri, Jan 04, 2019 at 01:22:26AM -0200, Eduardo Habkost wrote:
> > The virtio-pci entries in HW_COMPAT_2_6 had an implicit
> > assumption: that all virtio-pci subclasses support the
> > disable-legacy and disable-modern options.
> >
> > That assumption was broken by commit f6e501a28ef9 ("virtio:
> > Provide version-specific variants of virtio PCI devices"). This
> > caused QEMU to crash if using the new -non-transitional or
> > -transitional device types:
> >
> > $ qemu-system-x86_64 -machine pc-i440fx-2.6 \
> > -device virtio-net-pci-non-transitional
> > Unexpected error in object_property_find() at qom/object.c:1092:
> > qemu-system-x86_64: -device virtio-net-pci-non-transitional: can't apply \
> > global virtio-pci.disable-modern=on: Property '.disable-modern' not found
> > Aborted (core dumped)
> >
> > Replace the virtio-pci.disable-legacy=off and
> > virtio-pci.disable-modern=on entries on HW_COMPAT_2_6 with
> > explicit entries for each generic virtio device type.
> >
> > The full list of generic virtio device types was extracted by
> > just grepping for ".generic_name". Note that we don't need to
> > worry about listing new virtio-pci devices in HW_COMPAT_2_6 in
> > the future, because new devices won't require QEMU 2.6
> > compatibility.
>
> I fully expect that e.g. packed ring support will need
> to affect all virtio devices too. And it's likely
> that we'll have some new virtio-pci transport features too.
If you need to affect all virtio devices, you can still use
.driver="virtio-pci" on compat_props. This is just about the
disable-legacy and disable-modern properties.
>
> > This makes the compat entries annoyingly verbose, but is simpler
> > than the alternative of making the virtio-pci type inheritance
> > rules even more complex.
>
> God forbid we forgot something, the only way to notice is to
> run a cross version migration with an old qemu.
> I think we need to come up with something less verbose and fragile.
Both approaches can break if we forget something or do something
wrong. I don't think this one is more fragile than the others.
The difference is that this one lets us list the device types
once on compat_props and never think about it again. The others
would require us to worry forever about subtle interactions
between the disable-modern/disable-legacy properties and QOM
inheritance.
>
>
> > Reported-by: Thomas Huth <th...@redhat.com>
> > Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
> > ---
> > ---
> > include/hw/compat.h | 140 +++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 138 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/hw/compat.h b/include/hw/compat.h
> > index 3ca85b037c..fbb6c1138a 100644
> > --- a/include/hw/compat.h
> > +++ b/include/hw/compat.h
> > @@ -163,11 +163,147 @@
> > .property = "format_transport_address",\
> > .value = "off",\
> > },{\
> > - .driver = "virtio-pci",\
> > + .driver = "vhost-scsi-pci",\
> > .property = "disable-modern",\
> > .value = "on",\
> > },{\
> > - .driver = "virtio-pci",\
> > + .driver = "vhost-scsi-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "vhost-user-blk-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "vhost-user-blk-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "vhost-user-scsi-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "vhost-user-scsi-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "vhost-vsock-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "vhost-vsock-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-9p-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-9p-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-balloon-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-balloon-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-blk-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-blk-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-crypto-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-crypto-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-gpu-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-gpu-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-input-host-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-input-host-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-keyboard-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-keyboard-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-mouse-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-mouse-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-net-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-net-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-rng-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-rng-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-scsi-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-scsi-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-serial-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-serial-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-tablet-pci",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-tablet-pci",\
> > + .property = "disable-legacy",\
> > + .value = "off",\
> > + },{\
> > + .driver = "virtio-vga",\
> > + .property = "disable-modern",\
> > + .value = "on",\
> > + },{\
> > + .driver = "virtio-vga",\
> > .property = "disable-legacy",\
> > .value = "off",\
> > },
> > --
> > 2.18.0.rc1.1.g3f1ff2140
--
Eduardo
