[PATCH v2 08/15] KVM: MMU: introduce nulls desc

It likes nulls list and we use the pte-list as the nulls which can help us to detect whether the "desc" is moved to anther rmap then we can re-walk the rmap if that happened kvm->slots_lock is held when we do lockless walking that prevents rmap is reused (free rmap need to hold that lock) so that

[PATCH v2 08/15] KVM: MMU: introduce nulls desc

It likes nulls list and we use the pte-list as the nulls which can help us to detect whether the desc is moved to anther rmap then we can re-walk the rmap if that happened kvm-slots_lock is held when we do lockless walking that prevents rmap is reused (free rmap need to hold that lock) so that we