AMAIR_EL2, Auxiliary Memory Attribute Indirection Register (EL2)

The AMAIR_EL2 characteristics are:

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].

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 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 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 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 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];


26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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