Re: [PATCH v12 3/4] x86/cpu: Do a sanity check on required feature bits

[Pawan Gupta]

On Fri, Mar 27, 2026 at 03:10:58PM +0000, Maciej Wieczor-Retman wrote:
> +static void verify_required_features(const struct cpuinfo_x86 *c)
> +{
> +	u32 required_features[NCAPINTS + 1] = REQUIRED_MASK_INIT;
> +	char cap_buf[X86_NAMELESS_FEAT_BUFLEN];
> +	int i, error = 0;
> +
> +	for_each_set_bit(i, (unsigned long *)required_features, NCAPINTS * 32) {
> +		if (test_bit(i, (unsigned long *)c->x86_capability))

This can be simplified to:

		if (test_cpu_cap(c, i))

> +			continue;
> +		if (!error)
> +			pr_warn("CPU %d: missing required feature(s):", c->cpu_index);
> +		pr_cont(" %s", x86_feature_name(i, cap_buf));
> +		error = 1;
> +	}
> +
> +	if (!error)
> +		return;
> +
> +	pr_cont("\n");
> +	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
> +}