[tf-rmm] MPAMIDR_EL1

Hi,

I am trying to run TF-RMM and there's an exception while reading the MPAMIDR_EL1 register in rmm_arch_init().

if (is_feat_mpam_present()) { unsigned long mpamidr_el1 = read_mpamidr_el1(); .. }

The condition to access MPAMIDR_EL1 is: elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MPAM3_EL3.TRAPLOWER == '1' then UNDEFINED; elsif HaveEL(EL3) && MPAM3_EL3.TRAPLOWER == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = MPAMIDR_EL1;

I am running TF-A before TF-RMM, so the default value of 1 in MPAM3_EL3.TRAPLOWER forces all accesses to MPAMIDR_EL1 to be trapped to EL3. And the read in TF-RMM then causes an exception. But there's no handler for the trap in TF-RMM that can forward the read to EL3. Is my understanding right that the code to handle the trap is missing in RMM?

Thanks, Manoj