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ICH_VMCR_EL2, Interrupt Controller Virtual Machine Control Register

The ICH_VMCR_EL2 characteristics are:

Purpose

Enables the hypervisor to save and restore the virtual machine view of the GIC state.

Configuration

AArch64 System register ICH_VMCR_EL2 bits [31:0] are architecturally mapped to AArch32 System register ICH_VMCR[31:0] .

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

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

Attributes

ICH_VMCR_EL2 is a 64-bit register.

Field descriptions

The ICH_VMCR_EL2 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
VPMRVBPR0VBPR1RES0VEOIMRES0VCBPRVFIQEnVAckCtlVENG1VENG0
313029282726252423222120191817161514131211109876543210

Bits [63:32]

Reserved, RES0.

VPMR, bits [31:24]

Virtual Priority Mask. The priority mask level for the virtual CPU interface. If the priority of a pending virtual interrupt is higher than the value indicated by this field, the interface signals the virtual interrupt to the PE.

This field is an alias of ICV_PMR_EL1.Priority.

VBPR0, bits [23:21]

Virtual Binary Point Register, Group 0. Defines the point at which the priority value fields split into two parts, the group priority field and the subpriority field. The group priority field determines Group 0 interrupt preemption, and also determines Group 1 interrupt preemption if ICH_VMCR_EL2.VCBPR == 1.

This field is an alias of ICV_BPR0_EL1.BinaryPoint.

The minimum value of this field is determined by ICH_VTR_EL2.PREbits. An attempt to program the binary point field to a value less than the minimum value sets the field to the minimum value.

VBPR1, bits [20:18]

Virtual Binary Point Register, Group 1. Defines the point at which the priority value fields split into two parts, the group priority field and the subpriority field. The group priority field determines Group 1 interrupt preemption if ICH_VMCR_EL2.VCBPR == 0.

This field is an alias of ICV_BPR1_EL1.BinaryPoint.

This field is always accessible to EL2 accesses, regardless of the setting of the ICH_VMCR_EL2.VCBPR field.

For Non-secure writes, the minimum value of this field is the minimum value of ICH_VMCR_EL2.VBPR0 plus one.

For Secure writes, the minimum value of this field is the minimum value of ICH_VMCR_EL2.VBPR0.

An attempt to program the binary point field to a value less than the minimum value sets the field to the minimum value.

Bits [17:10]

Reserved, RES0.

VEOIM, bit [9]

Virtual EOI mode. Controls whether a write to an End of Interrupt register also deactivates the virtual interrupt:

VEOIMMeaning
0b0

ICV_EOIR0_EL1 and ICV_EOIR1_EL1 provide both priority drop and interrupt deactivation functionality. Accesses to ICV_DIR_EL1 are UNPREDICTABLE.

0b1

ICV_EOIR0_EL1 and ICV_EOIR1_EL1 provide priority drop functionality only. ICV_DIR_EL1 provides interrupt deactivation functionality.

This bit is an alias of ICV_CTLR_EL1.EOImode.

Bits [8:5]

Reserved, RES0.

VCBPR, bit [4]

Virtual Common Binary Point Register. Possible values of this bit are:

VCBPRMeaning
0b0

ICV_BPR1_EL1 determines the preemption group for virtual Group 1 interrupts.

0b1

Reads of ICV_BPR1_EL1 return ICV_BPR0_EL1 plus one, saturated to 0b111. Writes to ICV_BPR1_EL1 are ignored.

This field is an alias of ICV_CTLR_EL1.CBPR.

VFIQEn, bit [3]

Virtual FIQ enable. Possible values of this bit are:

VFIQEnMeaning
0b0

Group 0 virtual interrupts are presented as virtual IRQs.

0b1

Group 0 virtual interrupts are presented as virtual FIQs.

This bit is an alias of GICV_CTLR.FIQEn.

In implementations where the Non-secure copy of ICC_SRE_EL1.SRE is always 1, this bit is RES1.

VAckCtl, bit [2]

Virtual AckCtl. Possible values of this bit are:

VAckCtlMeaning
0b0

If the highest priority pending interrupt is Group 1, a read of GICV_IAR or GICV_HPPIR returns an INTID of 1022.

0b1

If the highest priority pending interrupt is Group 1, a read of GICV_IAR or GICV_HPPIR returns the INTID of the corresponding interrupt.

This bit is an alias of GICV_CTLR.AckCtl.

This field is supported for backwards compatibility with GICv2. Arm deprecates the use of this field.

In implementations where the Non-secure copy of ICC_SRE_EL1.SRE is always 1, this bit is RES0.

VENG1, bit [1]

Virtual Group 1 interrupt enable. Possible values of this bit are:

VENG1Meaning
0b0

Virtual Group 1 interrupts are disabled.

0b1

Virtual Group 1 interrupts are enabled.

This bit is an alias of ICV_IGRPEN1_EL1.Enable.

VENG0, bit [0]

Virtual Group 0 interrupt enable. Possible values of this bit are:

VENG0Meaning
0b0

Virtual Group 0 interrupts are disabled.

0b1

Virtual Group 0 interrupts are enabled.

This bit is an alias of ICV_IGRPEN0_EL1.Enable.

Accessing the ICH_VMCR_EL2

When EL2 is using System register access, EL1 using either System register or memory-mapped access must be supported.

Accesses to this register use the following encodings:

MRS <Xt>, ICH_VMCR_EL2

op0op1CRnCRmop2
0b110b1000b11000b10110b111
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then
        return NVMem[0x4C8];
    elsif EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    if ICC_SRE_EL2.SRE == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        return ICH_VMCR_EL2;
elsif PSTATE.EL == EL3 then
    if ICC_SRE_EL3.SRE == '0' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return ICH_VMCR_EL2;
              

MSR ICH_VMCR_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b11000b10110b111
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then
        NVMem[0x4C8] = X[t];
    elsif EL2Enabled() && HCR_EL2.NV == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    if ICC_SRE_EL2.SRE == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        ICH_VMCR_EL2 = X[t];
elsif PSTATE.EL == EL3 then
    if ICC_SRE_EL3.SRE == '0' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        ICH_VMCR_EL2 = X[t];
              


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