PRTB_MASK
ptbl = (table & PRTB_MASK) + (table_index * sizeof(entry));
!kvm_is_visible_gfn(vcpu->kvm, (ptcr & PRTB_MASK) >> PAGE_SHIFT))
ptbl_addr = (kvm->arch.l1_ptcr & PRTB_MASK) + (gp->l1_lpid << 4);
prtbl.address = dw1 & PRTB_MASK;