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# CNTHV_CVAL_EL2, Counter-timer Virtual Timer CompareValue Register (EL2)

The CNTHV_CVAL_EL2 characteristics are:

## Purpose

Holds the compare value for the EL2 virtual timer.

## Configuration

AArch64 System register CNTHV_CVAL_EL2 bits [63:0] are architecturally mapped to AArch32 System register CNTHV_CVAL[63:0].

This register is present only when FEAT_VHE is implemented and (EL3 is implemented or (EL3 is not implemented and FEAT_SEL2 is not implemented)). Otherwise, direct accesses to CNTHV_CVAL_EL2 are UNDEFINED.

If EL2 is not implemented, this register is RES0 from EL3.

## Attributes

CNTHV_CVAL_EL2 is a 64-bit register.

## Field descriptions

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
CompareValue
CompareValue

#### CompareValue, bits [63:0]

Holds the EL2 virtual timer CompareValue.

When CNTHV_CTL_EL2.ENABLE is 1, and TimerConditionMet is TRUE for the EL1 physical timer, the timer condition is met and all of the following are true:

- CNTHV_CTL_EL2.ISTATUS is set to 1.
- If CNTHV_CTL_EL2.IMASK is 0, an interrupt is generated.

TimerConditionMet is defined by 'Operation of the CompareValue views of the timers'.

The CompareValue view of the timer acts like a 64-bit upcounter timer.

When CNTHV_CTL_EL2.ENABLE is 0, the timer condition is not met, but CNTVCT_EL0 continues to count.

If the Generic counter is implemented at a size less than 64 bits, then this field is permitted to be implemented at the same width as the counter, and the upper bits are RES0.

The value of this field is treated as zero-extended in all counter calculations.

The reset behavior of this field is:

- On a Warm reset, this field resets to an architecturally UNKNOWN value.

## Accessing CNTHV_CVAL_EL2

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name CNTHV_CVAL_EL2 or CNTV_CVAL_EL0 are not guaranteed to be ordered with respect to accesses using the other accessor name.

Accesses to this register use the following encodings in the System register encoding space:

#### MRS <Xt>, CNTHV_CVAL_EL2

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b100 | 0b1110 | 0b0011 | 0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then X[t, 64] = CNTHV_CVAL_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = CNTHV_CVAL_EL2;

#### MSR CNTHV_CVAL_EL2, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b100 | 0b1110 | 0b0011 | 0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then CNTHV_CVAL_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then CNTHV_CVAL_EL2 = X[t, 64];

#### MRS <Xt>, CNTV_CVAL_EL0

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b1110 | 0b0011 | 0b010

if 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); 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 X[t, 64] = CNTHVS_CVAL_EL2; elsif ELIsInHost(EL0) && !IsCurrentSecurityState(SS_Secure) then X[t, 64] = CNTHV_CVAL_EL2; else X[t, 64] = CNTV_CVAL_EL0; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2.EL1TVT == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then X[t, 64] = NVMem[0x168]; else X[t, 64] = CNTV_CVAL_EL0; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then X[t, 64] = CNTHVS_CVAL_EL2; elsif ELIsInHost(EL2) && !IsCurrentSecurityState(SS_Secure) then X[t, 64] = CNTHV_CVAL_EL2; else X[t, 64] = CNTV_CVAL_EL0; elsif PSTATE.EL == EL3 then X[t, 64] = CNTV_CVAL_EL0;

#### MSR CNTV_CVAL_EL0, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b1110 | 0b0011 | 0b010

if 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); 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 = X[t, 64]; elsif ELIsInHost(EL0) && !IsCurrentSecurityState(SS_Secure) then CNTHV_CVAL_EL2 = X[t, 64]; else CNTV_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_ECV) && CNTHCTL_EL2.EL1TVT == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x168] = X[t, 64]; else CNTV_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && IsCurrentSecurityState(SS_Secure) && IsFeatureImplemented(FEAT_SEL2) then CNTHVS_CVAL_EL2 = X[t, 64]; elsif ELIsInHost(EL2) && !IsCurrentSecurityState(SS_Secure) then CNTHV_CVAL_EL2 = X[t, 64]; else CNTV_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL3 then CNTV_CVAL_EL0 = X[t, 64];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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