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GICR_VPENDBASER, Virtual Redistributor LPI Pending Table Base Address Register

The GICR_VPENDBASER characteristics are:

Purpose

Specifies the base address of the memory that holds the virtual LPI Pending table for the currently scheduled virtual machine.

Configuration

Attributes

GICR_VPENDBASER is a 64-bit register.

Field descriptions

The GICR_VPENDBASER bit assignments are:

When GICv4 is implemented:

Valid, bit [63]

This bit controls whether the virtual LPI Pending table is valid:

ValidMeaning
0b0

The virtual LPI Pending table is not valid. No vPE is scheduled.

0b1

The virtual LPI Pending table is valid. A vPE is scheduled.

Setting GICR_VPENDBASER.Valid == 1 when the associated CPU interface does not implement GICv4 is UNPREDICTABLE.

Note

Software can determine whether a PE supports GICv3 or GICv4 by reading ID_AA64PFR0_EL1.

Writing a new value to any bit of GICR_VPENDBASER, other than GICR_VPENDBASER.Valid, when GICR_VPENDBASER.Valid==1 is UNPREDICTABLE.

This field resets to 0.

IDAI, bit [62]

Implementation Defined Area Invalid. Indicates whether the IMPLEMENTATION DEFINED area in the virtual LPI Pending table is valid:

IDAIMeaning
0b0

The IMPLEMENTATION DEFINED area is valid.

0b1

The IMPLEMENTATION DEFINED area is invalid and all pending interrupt information is held in the architecturally defined part of the virtual LPI Pending table.

For more information, see LPI Pending tables and Virtual LPI Configuration tables and virtual LPI Pending tables.

This field resets to an architecturally UNKNOWN value.

PendingLast, bit [61]

Indicates whether there are pending and enabled interrupts for the last scheduled vPE.

This value is set by the implementation when GICR_VPENDBASER.Valid has been written from 1 to 0 and is otherwise UNKNOWN.

PendingLastMeaning
0b0

There are no pending and enabled interrupts for the last scheduled vPE.

0b1

There is at least one pending interrupt for the last scheduled vPE. It is IMPLEMENTATION DEFINED whether this bit is set when the only pending interrupts for the last scheduled vPE are not enabled.

Arm deprecates setting PendingLast to 1 when the only pending interrupts for the last scheduled virtual machine are not enabled.

When the GICR_VPENDBASER.Valid bit is written from 0 to 1, this bit is RES1.

This field resets to 0.

Dirty, bit [60]

When GICR_VPENDBASER.Valid == 0b0:

Indicates whether a de-scheduling operation is in progress.

This field is read-only.

DirtyMeaning
0b0

No de-scheduling operation in process.

0b1

De-scheduling operation in process.

Writing 1 to GICR_VPENDBASER.Valid is UNPREDICTABLE while GICR_VPENDBASER.Dirty==1.

This field resets to 0.


When GICR_VPENDBASER.Valid == 0b1 and GICR_TYPER.Dirty == 0b1:

This field is read-only. Reports whether the Virtual Pending table has been parsed.

DirtyMeaning
0b0

Parsing of the Virtual Pending Table has completed.

0b1

Parsing of the Virtual Pending Table has not completed.

Writing 1 to GICR_VPENDBASER.Valid is UNPREDICTABLE while GICR_VPENDBASER.Dirty == 1.

This field resets to 0.


Otherwise:

This field is read-only. This fields is UNKNOWN.

This field resets to 0.

Bit [59]

Reserved, RES0.

OuterCache, bits [58:56]

Indicates the Outer Cacheability attributes of accesses to virtual LPI Pending tables of vPEs targeting this Redistributor. The possible values of this field are:

OuterCacheMeaning
0b000

Memory type defined in InnerCache field. For Normal memory, Outer Cacheability is the same as Inner Cacheability.

0b001

Normal Outer Non-cacheable.

0b010

Normal Outer Cacheable Read-allocate, Write-through.

0b011

Normal Outer Cacheable Read-allocate, Write-back.

0b100

Normal Outer Cacheable Write-allocate, Write-through.

0b101

Normal Outer Cacheable Write-allocate, Write-back.

0b110

Normal Outer Cacheable Read-allocate, Write-allocate, Write-through.

0b111

Normal Outer Cacheable Read-allocate, Write-allocate, Write-back.

It is IMPLEMENTATION DEFINED whether this field has a fixed value or can be programmed by software. Implementing this field with a fixed value is deprecated.

The Cacheability, Outer Cacheability and Shareability fields are used for accesses to the virtual LPI Pending table of resident and non-resident vPEs.

If the OuterCacheabilty attribute of the virtual LPI Pending tables that are associated with vPEs targeting the same Redistributor are different, behavior is UNPREDICTABLE.

This field resets to an architecturally UNKNOWN value.

Bits [55:52]

Reserved, RES0.

Physical_Address, bits [51:16]

Bits [51:16] of the physical address containing the virtual LPI Pending table.

In implementations supporting fewer than 52 bits of physical address, unimplemented upper bits are RES0.

This field resets to an architecturally UNKNOWN value.

Bits [15:12]

Reserved, RES0.

Shareability, bits [11:10]

Indicates the Shareability attributes of accesses to the virtual LPI Pending table. The possible values of this field are:

ShareabilityMeaning
0b00

Non-shareable.

0b01

Inner Shareable.

0b10

Outer Shareable.

0b11

Reserved. Treated as 0b00.

It is IMPLEMENTATION DEFINED whether this field has a fixed value or can be programmed by software. Implementing this field with a fixed value is deprecated.

The Cacheability, Outer Cacheability and Shareability fields are used for accesses to the virtual LPI Pending table of resident and non-resident vPEs.

If the Shareability attribute of the virtual LPI Pending tables that are associated with vPEs targeting the same Redistributor are different, behavior is UNPREDICTABLE.

This field resets to an architecturally UNKNOWN value.

InnerCache, bits [9:7]

Indicates the Inner Cacheability attributes of accesses to the virtual LPI Pending table. The possible values of this field are:

InnerCacheMeaning
0b000

Device-nGnRnE.

0b001

Normal Inner Non-cacheable.

0b010

Normal Inner Cacheable Read-allocate, Write-through.

0b011

Normal Inner Cacheable Read-allocate, Write-back.

0b100

Normal Inner Cacheable Write-allocate, Write-through.

0b101

Normal Inner Cacheable Write-allocate, Write-back.

0b110

Normal Inner Cacheable Read-allocate, Write-allocate, Write-through.

0b111

Normal Inner Cacheable Read-allocate, Write-allocate, Write-back.

The Cacheability, Outer Cacheability and Shareability fields are used for accesses to the virtual LPI Pending table of resident and non-resident vPEs.

If the InnerCacheabilty attribute of the virtual LPI Pending tables that are associated with vPEs targeting the same Redistributor are different, behavior is UNPREDICTABLE.

This field resets to an architecturally UNKNOWN value.

Bits [6:0]

Reserved, RES0.

When GICv4.1 is implemented:
6362616059585756555453525150494847464544434241403938373635343332
ValidDoorbellPendingLastDirtyVGrp0EnVGrp1EnRES0
RES0vPEID
313029282726252423222120191817161514131211109876543210
313029282726252423222120191817161514131211109876543210

Valid, bit [63]

This bit controls whether a vPE is scheduled:

ValidMeaning
0b0

The virtual LPI Pending table is not valid. No vPE is scheduled.

0b1

The virtual LPI Pending table is valid. A vPE is scheduled.

Setting GICR_VPENDBASER.Valid == 1 when the associated CPU interface does not implement GICv4 is UNPREDICTABLE.

Note

Software can determine whether a PE supports GICv3 or GICv4 by reading ID_AA64PFR0_EL1.

Writing a new value to any bit of GICR_VPENDBASER, other than GICR_VPENDBASER.Valid, when GICR_VPENDBASER.Valid==1 is UNPREDICTABLE.

Setting GICR_VPENDBASER.Valid to 1 is UNPREDICTABLE if GICR_VPROPBASER.Valid == 0.

This field resets to 0.

Doorbell, bit [62]

When GICR_VPENDBASER.Valid is written from 1 to 0, this bit controls whether a default doorbell interrupt is requested for the descheduled vPE.

DoorbellMeaning
0b0

Default doorbell requested.

0b1

No default doorbell requested.

When GICR_VPENDBASER.Valid is written from 1 to 0, if there are outstanding enabled pending interrupts then this bit is treated as 0.

When GICR_VPENDBASER.Valid is written from 1 to 0, if GICR_VPENDBASER.PendingLast is written as 1 then this bit is treated as 0.

When GICR_VPENDBASER.Valid == 1, reads return an UNKNOWN value.

This field resets to an UNKNOWN value.

PendingLast, bit [61]

Indicates whether there are pending and enabled interrupts for the last scheduled vPE.

This value is set by the implementation when GICR_VPENDBASER.Valid is written from 1 to 0 and is otherwise UNKNOWN.

PendingLastMeaning
0b0

There are no pending and enabled interrupts for the last scheduled vPE.

0b1

There is at least one pending and enabled interrupt for the last scheduled vPE.

When the GICR_VPENDBASER.Valid bit is written from 0 to 1, this bit is RES1.

When GICR_VPENDBASER.Valid is written from 1 to 0, if GICR_VPENDBASER.PendingLast is written as 1, then this bit is set to an UNKNOWN value.

This field resets to an UNKNOWN value.

Dirty, bit [60]

When GICR_VPENDBASER.Valid == 0b0:

Read-only. Indicates whether a de-scheduling operation is in progress.

DirtyMeaning
0b0

No de-scheduling operation in progess.

0b1

De-scheduling operation in progess.

Writing 1 to GICR_VPENDBASER.Valid is UNPREDICTABLE while GICR_VPENDBASER.Dirty == 1.

This field resets to 0.


Otherwise:

Read-only. Reports whether the Virtual Pending table has been parsed.

DirtyMeaning
0b0

Parsing of the Virtual Pending Table is complete.

0b1

Parsing of the Virtual Pending Table has not completed.

Writing 1 to GICR_VPENDBASER.Valid is UNPREDICTABLE while GICR_VPENDBASER.Dirty == 1.

This field resets to 0.

VGrp0En, bit [59]

Enable virtual Group 0 interrupts.

VGrp0EnMeaning
0b0

Forwarding of virtual Group 0 interrupts disabled.

0b1

Forwarding of virtual Group 0 interrupts enabled.

This field resets to an UNKNOWN value.

VGrp1En, bit [58]

Enable virtual Group 1 interrupts.

VGrp1EnMeaning
0b0

Forwarding of virtual Group 1 interrupts disabled.

0b1

Forwarding of virtual Group 1 interrupts enabled.

This field resets to an UNKNOWN value.

Bits [57:16]

Reserved, RES0.

vPEID, bits [15:0]

When GICR_VPENDBASER.Valid == 1, ID of scheduled vPE.

When GICR_VPENDBASER.Valid == 1, if GICR_VPENDBASER.vPEID is set to a value greater than the configured vPEID width, the behavior of this field is CONSTRAINED UNPREDICTABLE:

  • GICR_VPENDBASER.vPEID is treated as having an UNKNOWN valid value for all purposes other than a direct read of the register.

  • GICR_VPENDBASER.Valid is treated as being set to 0 for all purposes other than a direct read of the register.

The size of this field is IMPLEMENTATION DEFINED, and is specified by the GICD_TYPER2.VIL and GICD_TYPER2.VID fields, unimplemented bits are RES0.

Accessing the GICR_VPENDBASER

The effect of a write to this register is not guaranteed to be visible throughout the affinity hierarchy, as indicated by GICR_CTLR.RWP == 0.

GICR_VPENDBASER can be accessed through the memory-mapped interfaces:

ComponentFrameOffsetInstance
GIC RedistributorVLPI_base0x0078GICR_VPENDBASER

This interface is accessible as follows:

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