Re: [PATCH v1 13/26] x86/cpuid: Scan CPUID(0x2)

[Ingo Molnar <mingo@kernel.org>]

* Ahmed S. Darwish <darwi@linutronix.de> wrote:

> +static void cpuid_read_0x2(const struct cpuid_scan_entry *e, struct cpuid_read_output *output)
> +{
> +	union leaf_0x2_regs *regs = (union leaf_0x2_regs *)output->leaf;
> +	struct leaf_0x2_0 *l2 = (struct leaf_0x2_0 *)output->leaf;
> +	int invalid_regs = 0;
> +
> +	/*
> +	 * All Intel CPUs must report an iteration count of 1.	In case of
> +	 * bogus hardware, keep the leaf marked as invalid at the CPUID table.
> +	 */
> +	cpuid_subleaf(e->leaf, e->subleaf, l2);
> +	if (l2->iteration_count != 0x01)
> +		return;
> +
> +	/*
> +	 * The most significant bit (MSB) of each register must be clear.
> +	 * If a register is malformed, replace its descriptors with NULL.
> +	 */
> +	for (int i = 0; i < 4; i++) {
> +		if (regs->reg[i].invalid) {
> +			regs->regv[i] = 0;
> +			invalid_regs++;
> +		}

Could we please emit a one-time syslog warning & diagnostic when we run 
across invalid or otherwise weird looking CPUID data, instead of just 
silently skipping and sanitizing it?

Thanks,

	Ingo