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 ARMv8.1-VHE is implemented. Otherwise, direct accesses to CNTHV_CVAL_EL2 are UNDEFINED.

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

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

CNTHV_CVAL_EL2 is a 64-bit register.

Field descriptions

The CNTHV_CVAL_EL2 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
CompareValue
CompareValue
313029282726252423222120191817161514131211109876543210

CompareValue, bits [63:0]

Holds the EL2 virtual timer CompareValue.

When CNTHV_CTL_EL2.ENABLE is 1, the timer condition is met when (CNTVCT_EL0 - 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 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.

This field resets to an architecturally UNKNOWN value.

Accessing the CNTHV_CVAL_EL2

When HCR_EL2.E2H is 1, without explicit synchronization, access from EL2 using the mnemonic CNTHV_CVAL_EL2 or CNTV_CVAL_EL0 are not guaranteed to be ordered with respect to accesses using the other mnemonic.

Accesses to this register use the following encodings:

MRS <Xt>, CNTHV_CVAL_EL2

op0op1CRnCRmop2
0b110b1000b11100b00110b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else return CNTHV_CVAL_EL2; elsif PSTATE.EL == EL3 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then AArch64.SystemAccessTrap(EL3, 0x18); else return CNTHV_CVAL_EL2;

MSR CNTHV_CVAL_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b11100b00110b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else CNTHV_CVAL_EL2 = X[t]; elsif PSTATE.EL == EL3 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then AArch64.SystemAccessTrap(EL3, 0x18); else CNTHV_CVAL_EL2 = X[t];

MRS <Xt>, CNTV_CVAL_EL0

op0op1CRnCRmop2
0b110b0110b11100b00110b010

if PSTATE.EL == EL0 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); elsif !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); 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_EL0; elsif PSTATE.EL == EL1 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else return CNTV_CVAL_EL0; elsif PSTATE.EL == EL2 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); elsif HCR_EL2.E2H == '1' && SCR_EL3.NS == '0' then return CNTHVS_CVAL_EL2; elsif HCR_EL2.E2H == '1' && SCR_EL3.NS == '1' then return CNTHV_CVAL_EL2; else return CNTV_CVAL_EL0; elsif PSTATE.EL == EL3 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then AArch64.SystemAccessTrap(EL3, 0x18); else return CNTV_CVAL_EL0;

MSR CNTV_CVAL_EL0, <Xt>

op0op1CRnCRmop2
0b110b0110b11100b00110b010

if PSTATE.EL == EL0 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); elsif !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '0' then CNTHVS_CVAL_EL2 = X[t]; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then CNTHV_CVAL_EL2 = X[t]; else CNTV_CVAL_EL0 = X[t]; elsif PSTATE.EL == EL1 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else CNTV_CVAL_EL0 = X[t]; elsif PSTATE.EL == EL2 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); elsif HCR_EL2.E2H == '1' && SCR_EL3.NS == '0' then CNTHVS_CVAL_EL2 = X[t]; elsif HCR_EL2.E2H == '1' && SCR_EL3.NS == '1' then CNTHV_CVAL_EL2 = X[t]; else CNTV_CVAL_EL0 = X[t]; elsif PSTATE.EL == EL3 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then AArch64.SystemAccessTrap(EL3, 0x18); else CNTV_CVAL_EL0 = X[t];




12/01/2022 09:56; 05a4944b4b04e7ab50def8c126b479d22136f35b

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