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AMAIR_EL2: Auxiliary Memory Attribute Indirection Register (EL2)

Purpose

Provides IMPLEMENTATION DEFINED memory attributes for the memory regions specified by MAIR_EL2.

Configuration

AArch64 System register AMAIR_EL2 bits [31:0] are architecturally mapped to AArch32 System register HAMAIR0[31:0].

AArch64 System register AMAIR_EL2 bits [63:32] are architecturally mapped to AArch32 System register HAMAIR1[31:0].

This register is present only when FEAT_AA64 is implemented. Otherwise, direct accesses to AMAIR_EL2 are UNDEFINED.

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

This register has no effect if EL2 is not enabled in the current Security state.

Attributes

AMAIR_EL2 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
IMPLEMENTATION DEFINED
IMPLEMENTATION DEFINED

AMAIR_EL2 is permitted to be cached in a TLB.

IMPLEMENTATION DEFINED, bits [63:0]

IMPLEMENTATION DEFINED.

The reset behavior of this field is:

Accessing AMAIR_EL2

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name AMAIR_EL2 or AMAIR_EL1 are not guaranteed to be ordered with respect to accesses using the other accessor name.

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

MRS <Xt>, AMAIR_EL2

op0op1CRnCRmop2
0b110b1000b10100b00110b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then X[t, 64] = AMAIR_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = AMAIR_EL2;

MSR AMAIR_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b10100b00110b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then AMAIR_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then AMAIR_EL2 = X[t, 64];

When FEAT_VHE is implemented

MRS <Xt>, AMAIR_EL1

op0op1CRnCRmop2
0b110b0000b10100b00110b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TRVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.AMAIR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then X[t, 64] = NVMem[0x148]; else X[t, 64] = AMAIR_EL1; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = AMAIR_EL2; else X[t, 64] = AMAIR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = AMAIR_EL1;

When FEAT_VHE is implemented

MSR AMAIR_EL1, <Xt>

op0op1CRnCRmop2
0b110b0000b10100b00110b000

if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.AMAIR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x148] = X[t, 64]; else AMAIR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then AMAIR_EL2 = X[t, 64]; else AMAIR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then AMAIR_EL1 = X[t, 64];