Re: [PATCH v6 7/9] crypto: x86/polyval: Add PCLMULQDQ accelerated implementation of POLYVAL

[Eric Biggers <ebiggers@kernel.org>]

On Wed, May 04, 2022 at 12:18:21AM +0000, Nathan Huckleberry wrote:
> +.macro schoolbook1_iteration i xor_sum
> +	movups (16*\i)(MSG), %xmm0
> +	.if (\i == 0 && \xor_sum == 1)
> +		pxor SUM, %xmm0
> +	.endif
> +        vpclmulqdq $0x01, (16*\i)(KEY_POWERS), %xmm0, %xmm2
> +        vpclmulqdq $0x00, (16*\i)(KEY_POWERS), %xmm0, %xmm1
> +        vpclmulqdq $0x10, (16*\i)(KEY_POWERS), %xmm0, %xmm3
> +        vpclmulqdq $0x11, (16*\i)(KEY_POWERS), %xmm0, %xmm4
> +        vpxor %xmm2, MI, MI
> +        vpxor %xmm1, LO, LO
> +        vpxor %xmm4, HI, HI
> +        vpxor %xmm3, MI, MI
> +.endm

The 8 lines above are indented with spaces.  They should use tabs, like
everywhere else.

> + * So our final computation is: T = T_1 : T_0 = g*(x) * P_0 V = V_1 : V_0 =
> + * g*(x) * (P_1 + T_0) p(x) / x^{128} mod g(x) = P_3 + P_1 + T_0 + V_1 : P_2 +
> + * P_0 + T_1 + V_0

This part is unreadable now -- it looks like you formatted it as regular text?
The three equations should be on their own lines, like how it was before.

> +__maybe_unused static const struct x86_cpu_id pcmul_cpu_id[] = {
> +	X86_MATCH_FEATURE(X86_FEATURE_PCLMULQDQ, NULL),
> +	X86_MATCH_FEATURE(X86_FEATURE_AVX, NULL),
> +	{}
> +};
> +MODULE_DEVICE_TABLE(x86cpu, pcmul_cpu_id);
> +
> +static int __init polyval_clmulni_mod_init(void)
> +{
> +	if (!x86_match_cpu(pcmul_cpu_id))
> +		return -ENODEV;
> +
> +	return crypto_register_shash(&polyval_alg);
> +}
> +
> +static void __exit polyval_clmulni_mod_exit(void)
> +{
> +	crypto_unregister_shash(&polyval_alg);
> +}

This won't work as intended; it's registering the algorithm (and autoloading the
module) if PCLMUL *or* AVX is available, rather than PCLMUL *and* AVX.

I think the way to go is to just have X86_FEATURE_PCLMULQDQ in the table, like
before, and add a check for boot_cpu_has(X86_FEATURE_AVX) in the init function.

- Eric