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CNTP_CVAL_EL0: Counter-timer Physical Timer CompareValue Register

Purpose

Holds the compare value for the EL1 physical timer.

Configuration

AArch64 System register CNTP_CVAL_EL0 bits [63:0] are architecturally mapped to AArch32 System register CNTP_CVAL[63:0].

Attributes

CNTP_CVAL_EL0 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
CompareValue
CompareValue

CompareValue, bits [63:0]

Holds the EL1 physical timer CompareValue.

When CNTP_CTL_EL0.ENABLE is 1, the timer condition is met when (CNTPCT_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 CNTP_CTL_EL0.ENABLE is 0, the timer condition is not met, but CNTPCT_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:

Accessing CNTP_CVAL_EL0

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, access from EL3 using the mnemonic CNTP_CVAL_EL0 or CNTP_CVAL_EL02 are not guaranteed to be ordered with respect to accesses using the other mnemonic.

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

MRS <Xt>, CNTP_CVAL_EL0

op0op1CRnCRmop2
0b110b0110b11100b00100b010

if PSTATE.EL == EL0 then if !ELIsInHost(EL0) && CNTKCTL_EL1.EL0PTEN == '0' then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELIsInHost(EL2) && CNTHCTL_EL2.EL1PCEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL2) && HCR_EL2.TGE == '0' && CNTHCTL_EL2.EL1PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && CNTHCTL_EL2.EL0PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then X[t, 64] = CNTHPS_CVAL_EL2; elsif ELIsInHost(EL0) && SCR_EL3.NS == '1' then X[t, 64] = CNTHP_CVAL_EL2; else X[t, 64] = CNTP_CVAL_EL0; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELIsInHost(EL2) && CNTHCTL_EL2.EL1PCEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL2) && CNTHCTL_EL2.EL1PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then X[t, 64] = NVMem[0x178]; else X[t, 64] = CNTP_CVAL_EL0; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then X[t, 64] = CNTHPS_CVAL_EL2; elsif ELIsInHost(EL2) && SCR_EL3.NS == '1' then X[t, 64] = CNTHP_CVAL_EL2; else X[t, 64] = CNTP_CVAL_EL0; elsif PSTATE.EL == EL3 then X[t, 64] = CNTP_CVAL_EL0;

MSR CNTP_CVAL_EL0, <Xt>

op0op1CRnCRmop2
0b110b0110b11100b00100b010

if PSTATE.EL == EL0 then if !ELIsInHost(EL0) && CNTKCTL_EL1.EL0PTEN == '0' then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELIsInHost(EL2) && CNTHCTL_EL2.EL1PCEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL2) && HCR_EL2.TGE == '0' && CNTHCTL_EL2.EL1PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && CNTHCTL_EL2.EL0PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL0) && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then CNTHPS_CVAL_EL2 = X[t, 64]; elsif ELIsInHost(EL0) && SCR_EL3.NS == '1' then CNTHP_CVAL_EL2 = X[t, 64]; else CNTP_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELIsInHost(EL2) && CNTHCTL_EL2.EL1PCEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif ELIsInHost(EL2) && CNTHCTL_EL2.EL1PTEN == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then NVMem[0x178] = X[t, 64]; else CNTP_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then CNTHPS_CVAL_EL2 = X[t, 64]; elsif ELIsInHost(EL2) && SCR_EL3.NS == '1' then CNTHP_CVAL_EL2 = X[t, 64]; else CNTP_CVAL_EL0 = X[t, 64]; elsif PSTATE.EL == EL3 then CNTP_CVAL_EL0 = X[t, 64];

MRS <Xt>, CNTP_CVAL_EL02

op0op1CRnCRmop2
0b110b1010b11100b00100b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then if EL2Enabled() && !ELIsInHost(EL0) && CNTHCTL_EL2.EL1NVPCT == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else X[t, 64] = NVMem[0x178]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = CNTP_CVAL_EL0; else UNDEFINED; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then X[t, 64] = CNTP_CVAL_EL0; else UNDEFINED;

MSR CNTP_CVAL_EL02, <Xt>

op0op1CRnCRmop2
0b110b1010b11100b00100b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then if EL2Enabled() && !ELIsInHost(EL0) && CNTHCTL_EL2.EL1NVPCT == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else NVMem[0x178] = X[t, 64]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then CNTP_CVAL_EL0 = X[t, 64]; else UNDEFINED; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then CNTP_CVAL_EL0 = X[t, 64]; else UNDEFINED;