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CNTVOFF_EL2, Counter-timer Virtual Offset register

The CNTVOFF_EL2 characteristics are:

Purpose

Holds the 64-bit virtual offset. This is the offset between the physical count value visible in CNTPCT_EL0 and the virtual count value visible in CNTVCT_EL0.

Configuration

AArch64 System register CNTVOFF_EL2 bits [63:0] are architecturally mapped to AArch32 System register CNTVOFF[63:0] .

If EL2 is not implemented, this register is RES0 from EL3 and the virtual counter uses a fixed virtual offset of zero.

Note

When EL2 is implemented and enabled in the current Security state, and is using AArch64, the virtual counter uses a fixed virtual offset of zero in the following situations:

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

CNTVOFF_EL2 is a 64-bit register.

Field descriptions

The CNTVOFF_EL2 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
Virtual offset
Virtual offset
313029282726252423222120191817161514131211109876543210

Bits [63:0]

Virtual offset.

This field resets to an architecturally UNKNOWN value.

Accessing the CNTVOFF_EL2

Accesses to this register use the following encodings:

MRS <Xt>, CNTVOFF_EL2

op0op1CRnCRmop2
0b110b1000b11100b00000b011
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then
        return NVMem[0x060];
    elsif EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    return CNTVOFF_EL2;
elsif PSTATE.EL == EL3 then
    return CNTVOFF_EL2;
              

MSR CNTVOFF_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b11100b00000b011
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then
        NVMem[0x060] = X[t];
    elsif EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    CNTVOFF_EL2 = X[t];
elsif PSTATE.EL == EL3 then
    CNTVOFF_EL2 = X[t];
              


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