ICH_VTR_EL2, Interrupt Controller VGIC Type Register

The ICH_VTR_EL2 characteristics are:

Purpose

Reports supported GIC virtualisartion features.

This register is part of:

Configuration

AArch64 System register ICH_VTR_EL2 is architecturally mapped to AArch32 System register ICH_VTR.

If EL2 is not implemented, all bits in this register are RES0 from EL3, except for nV4, which is RES1 from EL3.

Attributes

ICH_VTR_EL2 is a 32-bit register.

Field descriptions

The ICH_VTR_EL2 bit assignments are:

313029282726252423222120191817161514131211109876543210
PRIbitsPREbitsIDbitsSEISA3VnV4TDS00000000000000ListRegs

PRIbits, bits [31:29]

Priority bits. The number of virtual priority bits implemented, minus one.

An implementation must implement at least 32 levels of virtual priority (5 priority bits).

This field is an alias of ICV_CTLR_EL1.PRIbits.

PREbits, bits [28:26]

The number of virtual preemption bits implemented, minus one.

An implementation must implement at least 32 levels of virtual preemption priority (5 preemption bits).

The value of this field must be less than or equal to the value of ICH_VTR_EL2.PRIbits.

This field determines the minimum value of ICH_VMCR_EL2.VBPR0.

IDbits, bits [25:23]

The number of virtual interrupt identifier bits supported:

IDbitsMeaning
000

16 bits.

001

24 bits.

All other values are reserved.

This field is an alias of ICV_CTLR_EL1.IDbits.

SEIS, bit [22]

SEI Support. Indicates whether the virtual CPU interface supports generation of SEIs:

SEISMeaning
0

The virtual CPU interface logic does not support generation of SEIs.

1

The virtual CPU interface logic supports generation of SEIs.

This bit is an alias of ICV_CTLR_EL1.SEIS.

A3V, bit [21]

Affinity 3 Valid. Possible values are:

A3VMeaning
0

The virtual CPU interface logic only supports zero values of Affinity 3 in SGI generation System registers.

1

The virtual CPU interface logic supports non-zero values of Affinity 3 in SGI generation System registers.

This bit is an alias of ICV_CTLR_EL1.A3V.

nV4, bit [20]

Direct injection of virtual interrupts not supported. Possible values are:

nV4Meaning
0

The CPU interface logic supports direct injection of virtual interrupts.

1

The CPU interface logic does not support direct injection of virtual interrupts.

In GICv3 this bit is RES1.

TDS, bit [19]

Separate trapping of Non-secure EL1 writes to ICV_DIR_EL1 supported.

TDSMeaning
0

Implementation does not support ICH_HCR_EL2.TDIR.

1

Implementation supports ICH_HCR_EL2.TDIR.

Bits [18:5]

Reserved, RES0.

ListRegs, bits [4:0]

The number of implemented List registers, minus one. For example, a value of 0b01111 indicates that the maximum of 16 List registers are implemented.

Accessing the ICH_VTR_EL2

This register can be read using MRS with the following syntax:

MRS <Xt>, <systemreg>

This syntax uses the following encoding in the System instruction encoding space:

<systemreg> op1CRnCRmop2
ICH_VTR_EL210011001011001

Accessibility

The register is accessible as follows:

Control Accessibility
TGENSEL0EL1EL2EL3
x0 - - n/a RO
01 - - RORO
11 - n/a RORO

This table applies to all instructions that can access this register.

Traps and enables

For a description of the prioritization of any generated exceptions, see section D1.13.2 (Synchronous exception prioritization) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile. Subject to the prioritization rules, the following traps and enables are applicable when accessing this register.

In both Security states, and not dependent on other configuration bits:




02/05/2017 15:43

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