vmm_gpt_lvl_mask
const uint64_t mask = vmm_gpt_lvl_mask(node->vgn_level);
child->vgn_gpa = gpa & vmm_gpt_lvl_mask(parent->vgn_level);
mask = vmm_gpt_lvl_mask(lvl);
ASSERT0(gpa & ~vmm_gpt_lvl_mask(depth));
gpa = (gpa & vmm_gpt_lvl_mask(lvl)) + vmm_gpt_lvl_len(lvl);
uint64_t gpa = addr & vmm_gpt_lvl_mask(lvl);