GICH_VTR, Virtual Type Register

The GICH_VTR characteristics are:

Purpose

Indicates the number of implemented virtual priority bits and List registers.

This register is present only when FEAT_GICv3_LEGACY is implemented and EL2 is implemented. Otherwise, direct accesses to GICH_VTR are RES0.

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

GICH_VTR is a 32-bit register.

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
PRIbits			PREbits			IDbits			SEIS	A3V	RES0																ListRegs

The number of virtual priority bits implemented, minus one.

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

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 GICH_VTR.PRIbits.

The number of virtual interrupt identifier bits supported:

IDbits	Meaning
0b000	16 bits.
0b001	24 bits.

All other values are reserved.

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

SEIS	Meaning
0b0	The virtual CPU interface logic does not support generation of SEIs.
0b1	The virtual CPU interface logic supports generation of SEIs.

Affinity 3 valid. Possible values are:

A3V	Meaning
0b0	The virtual CPU interface logic only supports zero values of the Aff3 field in ICC_SGI0R_EL1, ICC_SGI1R_EL1, and ICC_ASGI1R_EL1.
0b1	The virtual CPU interface logic supports nonzero values of the Aff3 field in ICC_SGI0R_EL1, ICC_SGI1R_EL1, and ICC_ASGI1R_EL1.

Reserved, RES0.

The number of implemented List registers, minus one.

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

Component	Offset	Instance
GIC Virtual interface control	0x0004	GICH_VTR

This interface is accessible as follows:

26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6