mmu_alloc_root
root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level);
root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0,
root = mmu_alloc_root(vcpu, root_gfn, 0,
root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL);