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VAESKF2.VI

RISC-V VAESKF2.VI Instruction Details

Instruction ManualI-type

Vector AES-256 forward key-schedule step selected by uimm; SEW=32, no vm operand.

Instruction Syntax

vaeskf2.vi vd, vs2, uimm

Operand Breakdown

vd: destination vector register group.

vs2/vs1 or scalar source: selected by suffixes such as .vv, .vx, .vi, or .vf.

vm: when present, vm=0 uses v0 as the execution mask and vm=1 is unmasked.

ZvknedVector CryptoAES

Related Search Terms

vaeskf2.vi instruction RISC-V vaeskf2.vi vaeskf2.vi syntax vaeskf2.vi encoding Zvkned vector AES-256 forward key schedule

Instruction Behavior

vaeskf2.vi is the Zvkned AES-256 forward key-schedule instruction. It reads the current AES-256 round-key element group from vs2 and combines it with the previous round-key state in vd and the uimm-selected round number to generate the next round key, writing the result to vd. SEW must be 32. It is only for AES-256 forward key scheduling.

Quick Understanding & Search Notes

VAESKF2.VI is a Zvkned vector instruction for vector AES-256 forward key schedule. This page is checked against the official vector crypto extension and V-extension execution model.

Generates the next AES-256 forward key-schedule material using vs2 and the old vd state.

This element-group crypto instruction has no vm mask operand and executes at element-group granularity.

SEW=32, EGW=128, EGS=4; vl and vstart must be multiples of 4, and LMUL*VLEN must hold at least one element group.

RISC-V Unprivileged ISA Manual: Vector cryptography extensions 1.0 RISC-V Unprivileged ISA Manual: V standard vector extension

Vector Execution Context

When reading VAESKF2.VI, do not stop at the mnemonic. Official V-extension semantics also depend on the current vl, vtype, and mask state. .vi: one vector source and a small immediate participate.

Check vl first

The current vl determines the number of body elements. Typical code executes vsetvli, vsetivli, or vsetvl before this instruction.

Then check vtype

The current vtype supplies SEW, LMUL, tail policy, and mask policy; these affect element width, register-group size, and inactive/tail destination elements.

Then check vm/v0

For ordinary vector instructions with vm, vm=0 uses v0 as the execution mask and vm=1 is unmasked. A few forms such as VMERGE use v0 as data-selection input.

Official source: RISC-V V Standard Extension for Vector Operations

Common Usage Scenarios

Crypto & Security

Understand this scenario with real code like «vaeskf2.vi vd, vs2, uimm».

Vector Acceleration

Understand this scenario with real code like «vaeskf2.vi vd, vs2, uimm».

Pre-Use Checklist

Syntax Check

Confirm the current instruction format is I-type.
Confirm the operand order matches the example.

Semantic Check

Ensure the destination register usage is compatible with the calling convention.
Confirm this is not the lower-level form of a pseudo-instruction expansion.

Pitfalls / Common Confusions

No vm operand; this key-schedule instruction is not maskable.

SEW must be 32 and each element group is 128 bits.

Used for AES-256 forward key schedule; do not describe it as another AES round transform.

uimm round-number reserved/projection behavior follows the specification.

SEW=32, EGW=128, EGS=4; vl and vstart must be multiples of 4, and LMUL*VLEN must cover at least one 128-bit element group.

FAQ

Can VAESKF2.VI always use a v0.t mask?

No. This element-group crypto instruction has no vm operand; ordinary RVV mask syntax should not be added to examples.

What determines the element width for VAESKF2.VI?

This instruction fixes SEW=32 and executes on 128-bit element groups; other SEW values are reserved/illegal cases.