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S2PIR_EL2: Stage 2 Permission Indirection Register (EL2)

Purpose

Stage 2 Permission Indirection Register for EL1&0 translation regime.

Configuration

This register is present only when FEAT_S2PIE is implemented. Otherwise, direct accesses to S2PIR_EL2 are UNDEFINED.

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

Attributes

S2PIR_EL2 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
Perm15Perm14Perm13Perm12Perm11Perm10Perm9Perm8
Perm7Perm6Perm5Perm4Perm3Perm2Perm1Perm0

Perm<m>, bits [4m+3:4m], for m = 15 to 0

Represents stage 2 Base Permissions.

Perm<m>Meaning
0b0000

No Access.

0b0001

Reserved - treated as No Access.

0b0010

MRO.

0b0011

MRO-TL1.

0b0100

WO.

0b0101

Reserved - treated as No Access.

0b0110

MRO-TL0.

0b0111

MRO-TL01.

0b1000

RO.

0b1001

RO+uX.

0b1010

RO+pX.

0b1011

RO+puX.

0b1100

RW.

0b1101

RW+uX.

0b1110

RW+pX.

0b1111

RW+puX.

This field is permitted to be cached in a TLB.

When stage 2 Indirect Permission mechanism is disabled, the contents of this register are ignored.

The reset behavior of this field is:

Accessing S2PIR_EL2

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

MRS <Xt>, S2PIR_EL2

op0op1CRnCRmop2
0b110b1000b10100b00100b101

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'1x1'} then X[t, 64] = NVMem[0x2B0]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.PIEn == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.PIEn == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = S2PIR_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = S2PIR_EL2;

MSR S2PIR_EL2, <Xt>

op0op1CRnCRmop2
0b110b1000b10100b00100b101

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'1x1'} then NVMem[0x2B0] = X[t, 64]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.PIEn == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.PIEn == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else S2PIR_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then S2PIR_EL2 = X[t, 64];