Re: [PATCH v7 015/120] x86/cpu: Use parsed CPUID(0x80000002) to CPUID(0x80000004)

On Thu, 28 May 2026 17:37:37 +0200
"Ahmed S. Darwish" <[email protected]> wrote:

> For CPU brand string enumeration, use parsed CPUID(0x80000002) to
> CPUID(0x80000004) instead of invoking direct CPUID queries.
> 
> This centralizes CPUID invocation to the system's CPUID parser.
> 
> Signed-off-by: Ahmed S. Darwish <[email protected]>
> ---
>  arch/x86/kernel/cpu/common.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index 9b05a747161f..3d5b5df544d1 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -826,16 +826,18 @@ static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
>  
>  static void get_model_name(struct cpuinfo_x86 *c)
>  {
> -	unsigned int *v;
> +	const struct leaf_0x80000002_0 *l2 = cpuid_leaf(c, 0x80000002);
> +	const struct leaf_0x80000003_0 *l3 = cpuid_leaf(c, 0x80000003);
> +	const struct leaf_0x80000004_0 *l4 = cpuid_leaf(c, 0x80000004);
>  	char *p, *q, *s;
>  
> -	if (c->extended_cpuid_level < 0x80000004)
> +	if (!l2 || !l3 || !l4)
>  		return;
>  
> -	v = (unsigned int *)c->x86_model_id;
> -	cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
> -	cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
> -	cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
> +	*(struct leaf_0x80000002_0 *)&c->x86_model_id[0]  = *l2;
> +	*(struct leaf_0x80000003_0 *)&c->x86_model_id[16] = *l3;
> +	*(struct leaf_0x80000004_0 *)&c->x86_model_id[32] = *l4;

Those assignment are nasty.
You could probably use an anon union to do:
	c->x86_model_id_leaf_2 = *l2;

-- David


> +
>  	c->x86_model_id[48] = 0;
>  
>  	/* Trim whitespace */