VBAR_EL2 | Jon's Arm Reference

AArch64 System register VBAR_EL2 bits [31:0] are architecturally mapped to AArch32 System register HVBAR[31:0].

This register is present only when FEAT_AA64 is implemented. Otherwise, direct accesses to VBAR_EL2 are UNDEFINED.

This register has no effect if EL2 is not enabled in the current Security state.

Attributes

Field descriptions

VBA, bits [63:11]

Vector Base Address. Base address of the exception vectors for exceptions taken to EL2.

Note

If FEAT_LVA3 is implemented:

If the Effective value of HCR_EL2.E2H is 1:
- If tagged addresses are not being used, bits [63:56] of VBAR_EL2 must be the same or else the use of the vector address will result in a recursive exception.
If the Effective value of HCR_EL2.E2H is not 1:
- If tagged addresses are not being used, bits [63:56] of VBAR_EL2 must be 0 or else the use of the vector address will result in a recursive exception.

Otherwise :

If FEAT_LVA is implemented:

If the Effective value of HCR_EL2.E2H is 1:
- If tagged addresses are being used, bits [55:52] of VBAR_EL2 must be the same or else the use of the vector address will result in a recursive exception.
- If tagged addresses are not being used, bits [63:52] of VBAR_EL2 must be the same or else the use of the vector address will result in a recursive exception.
If the Effective value of HCR_EL2.E2H is not 1:
- If tagged addresses are being used, bits [55:52] of VBAR_EL2 must be 0 or else the use of the vector address will result in a recursive exception.
- If tagged addresses are not being used, bits [63:52] of VBAR_EL2 must be 0 or else the use of the vector address will result in a recursive exception.

If FEAT_LVA is not implemented:

If the Effective value of HCR_EL2.E2H is 1:
- If tagged addresses are being used, bits [55:48] of VBAR_EL2 must be the same or else the use of the vector address will result in a recursive exception.
- If tagged addresses are not being used, bits [63:48] of VBAR_EL2 must be the same or else the use of the vector address will result in a recursive exception.
If the Effective value of HCR_EL2.E2H is not 1:
- If tagged addresses are being used, bits [55:48] of VBAR_EL2 must be 0 or else the use of the vector address will result in a recursive exception.
- If tagged addresses are not being used, bits [63:48] of VBAR_EL2 must be 0 or else the use of the vector address will result in a recursive exception.

The reset behavior of this field is:

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

Bits [10:0]

Accessing VBAR_EL2

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name VBAR_EL2 or VBAR_EL1 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>, VBAR_EL2

op0	op1	CRn	CRm	op2
0b11	0b100	0b1100	0b0000	0b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif 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] = VBAR_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = VBAR_EL2;

MSR VBAR_EL2, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b100	0b1100	0b0000	0b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif 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 VBAR_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then VBAR_EL2 = X[t, 64];

When FEAT_VHE is implemented

MRS <Xt>, VBAR_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b1100	0b0000	0b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '011' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.VBAR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then X[t, 64] = NVMem[0x250]; else X[t, 64] = VBAR_EL1; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = VBAR_EL2; else X[t, 64] = VBAR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = VBAR_EL1;

When FEAT_VHE is implemented

MSR VBAR_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b1100	0b0000	0b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '011' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.VBAR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x250] = X[t, 64]; else VBAR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then VBAR_EL2 = X[t, 64]; else VBAR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then VBAR_EL1 = X[t, 64];

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VBA
VBA																					RES0

VBAR_EL2: Vector Base Address Register (EL2)

Purpose

Configuration

Attributes

Field descriptions

VBA, bits [63:11]

Bits [10:0]

Accessing VBAR_EL2

MRS <Xt>, VBAR_EL2

MSR VBAR_EL2, <Xt>

When FEAT_VHE is implemented

MRS <Xt>, VBAR_EL1

When FEAT_VHE is implemented

MSR VBAR_EL1, <Xt>