Re: [Qemu-devel] kvm: virtio-net: saved image requires TUN_F_UFO support

[Paolo Bonzini]

On 06/11/2017 10:38, Stefan Priebe - Profihost AG wrote:
> Hello,
> 
> i've upgraded some servers from kernel 4.4 to 4.12 - both running Qemu
> 2.9.1.
> 
> If i migrate a VM from a host running kernel 4.4 to a host running 4.12
> i get:
> 
> kvm: virtio-net: saved image requires TUN_F_UFO support
> kvm: Failed to load virtio-net-device:tmp
> 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: Invalid argument
> 
> 
> while migrating from 4.12 to 4.4 works fine.
> 
> Can anybody help? Is this expected?

Can you check why peer_has_ufo failed (in hw/net/virtio-net.c)?  Also,
did this ioctl fail when the tap device was set up on the 4.12 destination?

int tap_probe_has_ufo(int fd)
{
    unsigned offload;

    offload = TUN_F_CSUM | TUN_F_UFO;

    if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
        return 0;

    return 1;
}

Thanks,

Paolo