On Tue, May 21, 2024 at 6:23 AM Fabiano Rosas <faro...@suse.de> wrote:
>
> Fiona Ebner <f.eb...@proxmox.com> writes:
>
> > Migration from an 8.2 or 9.0 binary to an 8.1 binary with machine
> > version 8.1 can fail with:
> >
> >> kvm: Features 0x1c0010130afffa7 unsupported. Allowed features:
> >> 0x10179bfffe7
> >> kvm: Failed to load virtio-net:virtio
> >> kvm: error while loading state for instance 0x0 of device
> >> '0000:00:12.0/virtio-net'
> >> kvm: load of migration failed: Operation not permitted
> >
> > The series
> >
> > 53da8b5a99 virtio-net: Add support for USO features
> > 9da1684954 virtio-net: Add USO flags to vhost support.
> > f03e0cf63b tap: Add check for USO features
> > 2ab0ec3121 tap: Add USO support to tap device.
> >
> > only landed in QEMU 8.2, so the compatibility flags should be part of
> > machine version 8.1.
> >
> > Moving the flags unfortunately breaks forward migration with machine
> > version 8.1 from a binary without this patch to a binary with this
> > patch.
> >
> > Fixes: 53da8b5a99 ("virtio-net: Add support for USO features")
> > Signed-off-by: Fiona Ebner <f.eb...@proxmox.com>
>
> Reviewed-by: Fabiano Rosas <faro...@suse.de>
>
> I'll get to it eventually, but is this another one where just having
> -device virtio-net in the command line when testing cross-version
> migration would already have caught the issue?
Yes if you are using Qemu >= 8.2. Qemu has a default machine type for
each version.
Thanks
>
