SYS_PMBIDR_EL1
mrs_s x0, SYS_PMBIDR_EL1 // If SPE available at EL2,
!(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P);
reg = read_sysreg_s(SYS_PMBIDR_EL1);