HDBSSBR

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HDBSSBR_EL2, Hardware Dirty State Tracking Structure Base Register

Purpose

Configuration

This register is present only when FEAT_HDBSS is implemented and FEAT_AA64 is implemented. Otherwise, direct accesses to HDBSSBR_EL2 are UNDEFINED.

Attributes

Field descriptions

Bits [63:56]

BADDR, bits [55:12]

HDBSS base address, bits [55:12].

Bits [55:12] of the base address are the value of this field.
Bits [11:0] of the base address are 0.

Bits of this field above the implemented physical address size, indicated in ID_AA64MMFR0_EL1.PARange, are RES0.

Based on the value of the SZ field of this register, for encodings of the SZ field greater than 4KB, bits [(SZ+12-1):12] of this field are RES0 such that the base address of the HDBSS is aligned to its size.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Bits [11:4]

SZ, bits [3:0]

Size of the HDBSS.

SZ	Meaning
0b0000	4KB
0b0001	8KB
0b0010	16KB
0b0011	32KB
0b0100	64KB
0b0101	128KB
0b0110	256KB
0b0111	512KB
0b1000	1MB
0b1001	2MB

All other values are reserved.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing HDBSSBR_EL2

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

MRS <Xt>, HDBSSBR_EL2

op0	op1	CRn	CRm	op2
0b11	0b100	0b0010	0b0011	0b010

if !(IsFeatureImplemented(FEAT_HDBSS) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'1x1'} then X{64}(t) = NVMem(0x2E0); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().HDBSSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().HDBSSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = HDBSSBR_EL2(); end; elsif PSTATE.EL == EL3 then X{64}(t) = HDBSSBR_EL2(); end;

MSR HDBSSBR_EL2, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b100	0b0010	0b0011	0b010

if !(IsFeatureImplemented(FEAT_HDBSS) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'1x1'} then NVMem(0x2E0) = X{64}(t); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().HDBSSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().HDBSSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else HDBSSBR_EL2() = X{64}(t); end; elsif PSTATE.EL == EL3 then HDBSSBR_EL2() = X{64}(t); end;

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
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
RES0								BADDR
BADDR																				RES0								SZ