On Fri, Nov 2, 2018 at 5:59 AM, Liran Alon <liran.alon@xxxxxxxxxx> wrote: > >>> Therefore, I don't think that we want this versioning to be based on KVM_CAP at all. >>> It seems that we would want the process to behave as follows: >>> 1) Mgmt-layer at dest queries dest host max supported nested_state size. >>> (Which should be returned from kvm_check_extension(KVM_CAP_NESTED_STATE)) >>> 2) Mgmt-layer at source initiate migration to dest with requesting QEMU to send nested_state >>> matching dest max supported nested_state size. >>> When saving nested state using KVM_GET_NESTED_STATE IOCTL, QEMU will specify in nested_state->size >>> the *requested* size to be saved and KVM should be able to save only the information which matches >>> the version that worked with that size. >>> 3) After some sanity checks on received migration stream, dest host use KVM_SET_NESTED_STATE IOCTL. >>> This IOCTL should deduce which information it should deploy based on given nested_state->size. I have to object to any proposal which requires the management later to communicate with the source and the destination to determine what should be done.
