SATP_ASID_SHIFT
(cntx2asid(cntx) << SATP_ASID_SHIFT) |
asid_bits = old | (SATP_ASID_MASK << SATP_ASID_SHIFT);
asid_bits = (csr_read(CSR_SATP) >> SATP_ASID_SHIFT) & SATP_ASID_MASK;