ACTLRMASK_EL2 Auxiliary Control Masking Register (EL2) when FEAT_SRMASK is implemented and FEAT_AA64 is implemented Mask register to prevent updates of fields in ACTLR_EL2 on writes. Other If EL2 is not implemented, this register is RES0 from EL3. This register has no effect if EL2 is not enabled in the current Security state. ACTLRMASK_EL2 is a 64-bit register. IMPLEMENTATION DEFINED 63 0 63:0 IMPLEMENTATION DEFINED. When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name ACTLRMASK_EL2 or ACTLRMASK_EL1 are not guaranteed to be ordered with respect to accesses using the other accessor name. MRS <Xt>, ACTLRMASK_EL2 if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = ACTLRMASK_EL2(); end; elsif PSTATE.EL == EL3 then X{64}(t) = ACTLRMASK_EL2(); end; MSR ACTLRMASK_EL2, <Xt> if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif !IsZero(ACTLRMASK_EL2()) then Undefined(); else ACTLRMASK_EL2() = X{64}(t); end; elsif PSTATE.EL == EL3 then ACTLRMASK_EL2() = X{64}(t); end; MRS <Xt>, ACTLRMASK_EL1 if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGRTR2_EL2().nACTLRMASK_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2().SRMASKEn == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then X{64}(t) = NVMem(0x340); else X{64}(t) = ACTLRMASK_EL1(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then X{64}(t) = ACTLRMASK_EL2(); else X{64}(t) = ACTLRMASK_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = ACTLRMASK_EL1(); end; MSR ACTLRMASK_EL1, <Xt> if !(IsFeatureImplemented(FEAT_SRMASK) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGWTR2_EL2().nACTLRMASK_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2().SRMASKEn == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then NVMem(0x340) = X{64}(t); elsif !IsZero(ACTLRMASK_EL1()) then Undefined(); else ACTLRMASK_EL1() = X{64}(t); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().SRMASKEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().SRMASKEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then if !IsZero(ACTLRMASK_EL2()) then Undefined(); else ACTLRMASK_EL2() = X{64}(t); end; else ACTLRMASK_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then ACTLRMASK_EL1() = X{64}(t); end; 2026-03-26 20:27:25 2026-03_rel