ipmmu_ctx_read_root
if (read_poll_timeout_atomic(ipmmu_ctx_read_root, val,
reg = ipmmu_ctx_read_root(domain, IMCTR);
ipmmu_ctx_read_root(domain, IMBUSCR) &
ipmmu_ctx_write_root(domain, IMSTR, ipmmu_ctx_read_root(domain, IMSTR));
status = ipmmu_ctx_read_root(domain, IMSTR);
iova = ipmmu_ctx_read_root(domain, IMELAR);
iova |= (u64)ipmmu_ctx_read_root(domain, IMEUAR) << 32;