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ICH_AP1R<n>, Interrupt Controller Hyp Active Priorities Group 1 Registers, n = 0 - 3

The ICH_AP1R<n> characteristics are:

Purpose

Provides information about Group 1 active priorities for EL2.

Configuration

AArch32 System register ICH_AP1R<n> bits [31:0] are architecturally mapped to AArch64 System register ICH_AP1R<n>_EL2[31:0] .

If EL2 is not implemented, this register is RES0 from EL3.

Some or all RW fields of this register have defined reset values. These apply only if the PE resets into an Exception level that is using AArch32. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.

Attributes

ICH_AP1R<n> is a 32-bit register.

Field descriptions

The ICH_AP1R<n> bit assignments are:

313029282726252423222120191817161514131211109876543210
P31P30P29P28P27P26P25P24P23P22P21P20P19P18P17P16P15P14P13P12P11P10P9P8P7P6P5P4P3P2P1P0

P<x>, bit [x], for x = 0 to 31

Group 1 interrupt active priorities. Possible values of each bit are:

P<x>Meaning
0b0

There is no Group 1 interrupt active at the priority corresponding to that bit.

0b1

There is a Group 1 interrupt active at the priority corresponding to that bit.

The correspondence between priority levels and bits depends on the number of bits of priority that are implemented.

If 5 bits of preemption are implemented (bits [7:3] of priority), then there are 32 preemption levels, and the active state of these preemption levels are held in ICH_AP1R0 in the bits corresponding to Priority[7:3].

If 6 bits of preemption are implemented (bits [7:2] of priority), then there are 64 preemption levels, and:

  • The active state of preemption levels 0 - 124 are held in ICH_AP1R0 in the bits corresponding to 0:Priority[6:2].
  • The active state of preemption levels 128 - 252 are held in ICH_AP1R1 in the bits corresponding to 1:Priority[6:2].

If 7 bits of preemption are implemented (bits [7:1] of priority), then there are 128 preemption levels, and:

  • The active state of preemption levels 0 - 62 are held in ICH_AP1R0 in the bits corresponding to 00:Priority[5:1].
  • The active state of preemption levels 64 - 126 are held in ICH_AP1R1 in the bits corresponding to 01:Priority[5:1].
  • The active state of preemption levels 128 - 190 are held in ICH_AP1R2 in the bits corresponding to 10:Priority[5:1].
  • The active state of preemption levels 192 - 254 are held in ICH_AP1R3 in the bits corresponding to 11:Priority[5:1].
Note

Having the bit corresponding to a priority set to 1 in both ICH_AP0R<n> and ICH_AP1R<n> might result in UNPREDICTABLE behavior of the interrupt prioritization system for virtual interrupts.

This field resets to 0.

Accessing the ICH_AP1R<n>

ICH_AP1R1 is only implemented in implementations that support 6 or more bits of preemption. ICH_AP1R2 and ICH_AP1R3 are only implemented in implementations that support 7 bits of preemption. Unimplemented registers are UNDEFINED.

Note

The number of bits of preemption is indicated by ICH_VTR.PREbits

Writing to the active priority registers in any order other than the following order will result in UNPREDICTABLE behavior:

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

opc1opc2CRncoprocCRm
0b1000b0[n:1:0]0b11000b11110b1001
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    if ICC_HSRE.SRE == '0' then
        UNDEFINED;
    else
        return ICH_AP1R[UInt(opc2<1:0>)];
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        return ICH_AP1R[UInt(opc2<1:0>)];

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

opc1opc2CRncoprocCRm
0b1000b0[n:1:0]0b11000b11110b1001
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    if ICC_HSRE.SRE == '0' then
        UNDEFINED;
    else
        ICH_AP1R[UInt(opc2<1:0>)] = R[t];
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        ICH_AP1R[UInt(opc2<1:0>)] = R[t];


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