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CNTHVS_CVAL, Counter-timer Secure Virtual Timer CompareValue Register (EL2)

The CNTHVS_CVAL characteristics are:

Purpose

Provides AArch32 access to the compare value for the Secure EL2 virtual timer.

Note

The Secure EL2 timer is implemented by ARMv8.4-SecEL2. It is only accessible from AArch32 state when EL2 is using AArch64 and the value of SCR_EL3.{EEL2, NS} is {1, 0}.

Configuration

AArch32 System register CNTHVS_CVAL bits [63:0] are architecturally mapped to AArch64 System register CNTHVS_CVAL_EL2[63:0] .

This register is present only when ARMv8.4-SecEL2 is implemented. Otherwise, direct accesses to CNTHVS_CVAL are UNDEFINED.

Attributes

CNTHVS_CVAL is a 64-bit register.

Field descriptions

The CNTHVS_CVAL bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
CompareValue
CompareValue
313029282726252423222120191817161514131211109876543210

CompareValue, bits [63:0]

Holds the EL2 virtual timer CompareValue.

When CNTHVS_CTL.ENABLE is 1, the timer condition is met when (CNTVCT - CompareValue) is greater than or equal to zero. This means that CompareValue acts like a 64-bit upcounter timer. When the timer condition is met:

When CNTHVS_CTL.ENABLE is 0, the timer condition is not met, but CNTVCT 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.

Accessing the CNTHVS_CVAL

This register is accessed using the encoding for CNTV_CVAL.

Accesses to this register use the following encodings:

MRRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <Rt2>, <CRm>

coprocCRmopc1
0b11110b11100b0011
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        else
            AArch64.AArch32SystemAccessTrap(EL1, 0x04);
    elsif ELUsingAArch32(EL1) && CNTKCTL.PL0VTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then
            AArch32.TakeHypTrapException(0x00);
        else
            UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x04);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '0' then
        return CNTHVS_CVAL_EL2;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then
        return CNTHV_CVAL_EL2;
    else
        return CNTV_CVAL;
elsif PSTATE.EL == EL1 then
    return CNTV_CVAL;
elsif PSTATE.EL == EL2 then
    return CNTV_CVAL;
elsif PSTATE.EL == EL3 then
    return CNTV_CVAL;
              

MCRR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <Rt2>, <CRm>

coprocCRmopc1
0b11110b11100b0011
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        else
            AArch64.AArch32SystemAccessTrap(EL1, 0x04);
    elsif ELUsingAArch32(EL1) && CNTKCTL.PL0VTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then
            AArch32.TakeHypTrapException(0x00);
        else
            UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x04);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '0' then
        CNTHVS_CVAL_EL2 = R[t2]:R[t];
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then
        CNTHV_CVAL_EL2 = R[t2]:R[t];
    else
        CNTV_CVAL = R[t2]:R[t];
elsif PSTATE.EL == EL1 then
    CNTV_CVAL = R[t2]:R[t];
elsif PSTATE.EL == EL2 then
    CNTV_CVAL = R[t2]:R[t];
elsif PSTATE.EL == EL3 then
    CNTV_CVAL = R[t2]:R[t];
              


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