VMPIDR

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VMPIDR, Virtualization Multiprocessor ID Register

Purpose

Holds the value of the Virtualization Multiprocessor ID. This is the value returned by Non-secure EL1 reads of MPIDR, which in a multiprocessor system, provides an additional PE identification system.

Configuration

AArch32 System register VMPIDR bits [31:0] are architecturally mapped to AArch64 System register VMPIDR_EL2[31:0].

This register is present only when FEAT_AA32EL2 is implemented. Otherwise, direct accesses to VMPIDR are UNDEFINED.

If EL2 is not implemented but EL3 is implemented, this register takes the value of the MPIDR.

Attributes

Field descriptions

M, bit [31]

Indicates whether this implementation includes the functionality introduced by the Armv7 Multiprocessing Extensions.

M	Meaning
0b0	This implementation does not include the Armv7 Multiprocessing Extensions functionality.
0b1	This implementation includes the Armv7 Multiprocessing Extensions functionality.

Access to this field is RES1 .

U, bit [30]

Indicates a Uniprocessor system, as distinct from PE 0 in a multiprocessor system.

U	Meaning
0b0	Processor is part of a multiprocessor system.
0b1	Processor is part of a uniprocessor system.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to the value in MPIDR.U.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Bits [29:25]

MT, bit [24]

Indicates whether the lowest level of affinity consists of logical PEs that are implemented using a multithreading type approach. See the description of Aff0 for more information about affinity levels.

MT	Meaning
0b0	Performance of PEs at the lowest affinity level is largely independent.
0b1	Performance of PEs at the lowest affinity level is very interdependent.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to the value in MPIDR.MT.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Aff2, bits [23:16]

Aff1, bits [15:8]

Aff0, bits [7:0]

Affinity level 0. The value of the MPIDR.{Aff2, Aff1, Aff0} or MPIDR_EL1.{Aff3, Aff2, Aff1, Aff0} set of fields of each PE must be unique within the system as a whole.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to the value in MPIDR.Aff0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Accessing VMPIDR

Accesses to this register use the following encodings in the System register encoding space:

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0000	0b0000	0b101

if !IsFeatureImplemented(FEAT_AA32EL2) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T0 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T0 == '1' then AArch32_TakeHypTrapException(0x03); else Undefined(); end; elsif PSTATE.EL == EL2 then R(t) = VMPIDR(); elsif PSTATE.EL == EL3 then if !HaveEL(EL2) then R(t) = MPIDR(); elsif SCR().NS == '0' then Undefined(); else R(t) = VMPIDR(); end; end;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0000	0b0000	0b101

if !IsFeatureImplemented(FEAT_AA32EL2) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T0 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T0 == '1' then AArch32_TakeHypTrapException(0x03); else Undefined(); end; elsif PSTATE.EL == EL2 then VMPIDR() = R(t); elsif PSTATE.EL == EL3 then if !HaveEL(EL2) then return; elsif SCR().NS == '0' then Undefined(); else VMPIDR() = R(t); end; end;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b000	0b0000	0b0000	0b101

if !IsFeatureImplemented(FEAT_AA32EL1) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T0 == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T0 == '1' then AArch32_TakeHypTrapException(0x03); elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) then R(t) = VMPIDR_EL2()[31:0]; elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) then R(t) = VMPIDR(); else R(t) = MPIDR(); end; elsif PSTATE.EL == EL2 then R(t) = MPIDR(); elsif PSTATE.EL == EL3 then R(t) = MPIDR(); end;

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
M	U	RES0					MT	Aff2								Aff1								Aff0