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GICV_EOIR, Virtual Machine End Of Interrupt Register

The GICV_EOIR characteristics are:

Purpose

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

This register corresponds to the physical CPU interface register GICC_EOIR.

Configuration

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

Attributes

GICV_EOIR is a 32-bit register.

Field descriptions

The GICV_EOIR bit assignments are:

313029282726252423222120191817161514131211109876543210
0000000INTID

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.

The behavior of this register depends on the setting of GICV_CTLR.EOImode:

GICV_CTLR.EOImodeBehavior
0b0Both the priority drop and the deactivate interrupt effects occur
0b1Only the priority drop effect occurs.

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 GICH_LR<n>. If GICH_LR<n>.HW == 1, indicating the INTID corresponds to a hardware interrupt, a deactivate request is also sent to the physical Distributor, identifying the physical INTID from the corresponding field in the List register. This effect is identical to a Non-secure write to GICC_DIR from the PE having that physical INTID. This means that if the corresponding physical interrupt is marked as Group 0, and GICD_CTLR.DS == 0, the deactivation request is ignored. See GICC_EOIR for more information.
Note

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

Accessing the GICV_EOIR

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

  • For AArch32 implementations, ICC_EOIR0 provides equivalent functionality.
  • For AArch64 implementations, ICC_EOIR0_EL1 provides equivalent functionality.

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

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

GICV_EOIR can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
GIC Virtual CPU interface0x0010GICV_EOIR

This interface is accessible as follows:

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


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