CNTV_TVAL_EL0 Counter-timer Virtual Timer TimerValue Register when FEAT_AA64 is implemented CNTV_TVAL Architectural AArch32 31 0 31 0 31 0 31 0 Holds the timer value for the EL1 virtual timer. Timer CNTV_TVAL_EL0 is a 64-bit register. 63 32 63:32 Reserved, RES0. TimerValue 31 0 31:0 The TimerValue view of the EL1 virtual timer. On a read of this register: If CNTV_CTL_EL0.ENABLE is 0, the value returned is UNKNOWN. If CNTV_CTL_EL0.ENABLE is 1, the value returned is (CNTV_CVAL_EL0 - CNTVCT_EL0). On a write of this register, CNTV_CVAL_EL0 is set to (CNTVCT_EL0 + TimerValue), where TimerValue is treated as a signed 32-bit integer. When CNTV_CTL_EL0.ENABLE is 1, the timer condition is met when (CNTVCT_EL0 - CNTV_CVAL_EL0) is greater than or equal to zero. This means that TimerValue acts like a 32-bit downcounter timer. When the timer condition is met: CNTV_CTL_EL0.ISTATUS is set to 1. If CNTV_CTL_EL0.IMASK is 0, an interrupt is generated. When CNTV_CTL_EL0.ENABLE is 0, the TimerValue cannot be read but continues to decrement. When the timer is enabled, the TimerValue represents the elapsed time whether that time was spent enabled or disabled. AU When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL3 using the accessor name CNTV_TVAL_EL0 or CNTV_TVAL_EL02 are not guaranteed to be ordered with respect to accesses using the other accessor name. MRS <Xt>, CNTV_TVAL_EL0 if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then if !ELIsInHost(EL0) && CNTKCTL_EL1().EL0VTEN == '0' then if EL2Enabled() && HCR_EL2().TGE == '1' then AArch64_SystemAccessTrap(EL2, 0x18); else AArch64_SystemAccessTrap(EL1, 0x18); end; elsif ELIsInHost(EL0) && CNTHCTL_EL2().EL0VTEN == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && !ELIsInHost(EL0) && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2().EL1TVT == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then if CNTHVS_CTL_EL2().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTHVS_CVAL_EL2() - PhysicalCountInt())[31:0]); end; elsif ELIsInHost(EL0) && !IsCurrentSecurityState(SS_Secure) then if CNTHV_CTL_EL2().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTHV_CVAL_EL2() - PhysicalCountInt())[31:0]); end; elsif HaveEL(EL2) && !ELIsInHost(EL0) then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); end; else if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - PhysicalCountInt())[31:0]); end; end; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2().EL1TVT == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL2) then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); end; else if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - PhysicalCountInt())[31:0]); end; end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then if CNTHVS_CTL_EL2().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTHVS_CVAL_EL2() - PhysicalCountInt())[31:0]); end; elsif ELIsInHost(EL2) && !IsCurrentSecurityState(SS_Secure) then if CNTHV_CTL_EL2().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTHV_CVAL_EL2() - PhysicalCountInt())[31:0]); end; elsif !ELIsInHost(EL2) then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); end; else if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - PhysicalCountInt())[31:0]); end; end; elsif PSTATE.EL == EL3 then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); elsif HaveEL(EL2) && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) then X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); elsif HaveEL(EL2) && IsFeatureImplemented(FEAT_AA32EL2) then X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF()))[31:0]); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - PhysicalCountInt())[31:0]); end; end; MSR CNTV_TVAL_EL0, <Xt> if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then if !ELIsInHost(EL0) && CNTKCTL_EL1().EL0VTEN == '0' then if EL2Enabled() && HCR_EL2().TGE == '1' then AArch64_SystemAccessTrap(EL2, 0x18); else AArch64_SystemAccessTrap(EL1, 0x18); end; elsif ELIsInHost(EL0) && CNTHCTL_EL2().EL0VTEN == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && !ELIsInHost(EL0) && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2().EL1TVT == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then CNTHVS_CVAL_EL2() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); elsif ELIsInHost(EL0) && !IsCurrentSecurityState(SS_Secure) then CNTHV_CVAL_EL2() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); elsif HaveEL(EL2) && !ELIsInHost(EL0) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); else CNTV_CVAL_EL0() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); end; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2().EL1TVT == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); else CNTV_CVAL_EL0() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then CNTHVS_CVAL_EL2() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); elsif ELIsInHost(EL2) && !IsCurrentSecurityState(SS_Secure) then CNTHV_CVAL_EL2() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); elsif !ELIsInHost(EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); else CNTV_CVAL_EL0() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); end; elsif PSTATE.EL == EL3 then if HaveEL(EL2) && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); elsif HaveEL(EL2) && IsFeatureImplemented(FEAT_AA32EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF(); else CNTV_CVAL_EL0() = SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt(); end; end; MRS <Xt>, CNTV_TVAL_EL02 When FEAT_VHE is implemented if !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 ELIsInHost(EL2) then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); end; else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then if CNTV_CTL_EL0().ENABLE == '0' then X{64}(t) = ARBITRARY:bits(64); else X{64}(t) = ZeroExtend{64}((CNTV_CVAL_EL0() - (PhysicalCountInt() - CNTVOFF_EL2()))[31:0]); end; else Undefined(); end; end; MSR CNTV_TVAL_EL02, <Xt> When FEAT_VHE is implemented if !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 ELIsInHost(EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then CNTV_CVAL_EL0() = (SignExtend{64}(X{64}(t)[31:0]) + PhysicalCountInt()) - CNTVOFF_EL2(); else Undefined(); end; end; 2026-03-26 20:27:25 2026-03_rel