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GICV_AEOIR, Virtual Machine Aliased End Of Interrupt Register

The GICV_AEOIR characteristics are:

Purpose

A write to this register performs a priority drop for the specified Group 1 virtual interrupt and, if GICV_CTLR.EOImode == 0, also deactivates the interrupt.

Configuration

This register is available when the GIC implementation supports interrupt virtualization.

Attributes

GICV_AEOIR is a 32-bit register.

Field descriptions

The GICV_AEOIR bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0INTID

Bits [31:25]

Reserved, RES0.

INTID, bits [24:0]

The INTID of the signaled interrupt.

Note

INTIDs 1020-1023 are reserved and convey additional information such as spurious interrupts.

When affinity routing is not enabled:

  • Bits [23:13] are RES0.
  • For SGIs, bits [12:10] identify the CPU interface corresponding to the source PE. For all other interrupts these bits are RES0.

A successful EOI request means that:

  • The highest priority bit in GICH_APR<n> is cleared, causing the running priority to drop.
  • If the appropriate GICV_CTLR.EOImode bit == 0, the interrupt is deactivated in the corresponding List register. If the INTID corresponds to a hardware interrupt, the interrupt is also deactivated in the Distributor.
Note

Only Group 1 interrupts can target the hypervisor, and therefore only Group 1 interrupts are deactivated in the Distributor.

A write to this register is UNPREDICTABLE if the INTID corresponds to a Group 0 interrupt. In addition, the following GICv2 UNPREDICTABLE cases require specific actions:

  • If highest active priority is Group 0 and the identified interrupt is in the List Registers and it matches the highest active priority. When EL2 is using System registers and ICH_VTR_EL2.SEIS is 1, an IMPLEMENTATION DEFINED SEI might be generated, otherwise GICv3 implementations must ignore such writes.
  • If the identified interrupt is in the List Registers, and the HW bit is 1, and the interrupt to be deactivated is an SGI (that is, the value of Physical_ID is between 0 and 15). GICv3 implementations must perform the deactivate operation. This means that a GICv3 implementation in legacy operation must ensure only a single SGI is active for a PE.
  • If the identified interrupt is in the List Registers, and the HW bit is 1, and the corresponding pINTID field value is between 1020 and 1023, indicating a special purpose INTID. GICv3 implementations must not perform a deactivate operation but must still change the state of the List register as appropriate. When EL2 is using System registers and ICH_VTR_EL2.SEIS is 1, an implementation might generate a system error.

Accessing the GICV_AEOIR

This register is used only when System register access is not enabled. When System register access is enabled:

  • For AArch32 implementations, ICC_EOIR1 provides equivalent functionality.
  • For AArch64 implementations, ICC_EOIR1_EL1 provides equivalent functionality.

This register is used for Group 1 interrupts only. GICV_EOIR provides equivalent functionality for Group 0 interrupts.

When affinity routing is enabled, it is a programming error to use memory-mapped registers to access the GIC.

GICV_AEOIR can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
GIC Virtual CPU interface0x0024GICV_AEOIR

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0b0 accesses to this register are WO.
  • When IsAccessSecure() accesses to this register are WO.
  • When !IsAccessSecure() accesses to this register are WO.


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