[PATCH 12/12] RISC-V: crypto: add Zvkb accelerated ChaCha20 implementation

[Eric Biggers]

On Thu, Oct 26, 2023 at 02:36:44AM +0800, Jerry Shih wrote:
> +static struct skcipher_alg riscv64_chacha_alg_zvkb[] = { {
> +	.base = {
> +		.cra_name = "chacha20",
> +		.cra_driver_name = "chacha20-riscv64-zvkb",
> +		.cra_priority = 300,
> +		.cra_blocksize = 1,
> +		.cra_ctxsize = sizeof(struct chacha_ctx),
> +		.cra_module = THIS_MODULE,
> +	},
> +	.min_keysize = CHACHA_KEY_SIZE,
> +	.max_keysize = CHACHA_KEY_SIZE,
> +	.ivsize = CHACHA_IV_SIZE,
> +	.chunksize = CHACHA_BLOCK_SIZE,
> +	.walksize = CHACHA_BLOCK_SIZE * 4,
> +	.setkey = chacha20_setkey,
> +	.encrypt = chacha20_encrypt,
> +	.decrypt = chacha20_encrypt,
> +} };
> +
> +static inline bool check_chacha20_ext(void)
> +{
> +	return riscv_isa_extension_available(NULL, ZVKB) &&
> +	       riscv_vector_vlen() >= 128;
> +}
> +
> +static int __init riscv64_chacha_mod_init(void)
> +{
> +	if (check_chacha20_ext())
> +		return crypto_register_skciphers(
> +			riscv64_chacha_alg_zvkb,
> +			ARRAY_SIZE(riscv64_chacha_alg_zvkb));
> +
> +	return -ENODEV;
> +}
> +
> +static void __exit riscv64_chacha_mod_fini(void)
> +{
> +	if (check_chacha20_ext())
> +		crypto_unregister_skciphers(
> +			riscv64_chacha_alg_zvkb,
> +			ARRAY_SIZE(riscv64_chacha_alg_zvkb));
> +}

When there's just one algorithm being registered/unregistered,
crypto_register_skcipher() and crypto_unregister_skcipher() can be used.

> +# - RV64I
> +# - RISC-V Vector ('V') with VLEN >= 128
> +# - RISC-V Vector Cryptography Bit-manipulation extension ('Zvkb')
> +# - RISC-V Zicclsm(Main memory supports misaligned loads/stores)

How is the presence of the Zicclsm extension guaranteed?

- Eric