Re: [PATCH 1/3] x86/resctrl: Get max rmid and occupancy scale directly from CPUID instead of cpuinfo_x86

[Borislav Petkov]

On Sun, Jun 16, 2019 at 10:14:08AM -0700, Fenghua Yu wrote:
> @@ -617,13 +617,20 @@ static void l3_mon_evt_init(struct rdt_resource *r)
>  		list_add_tail(&mbm_local_event.list, &r->evt_list);
>  }
>  
> -int rdt_get_mon_l3_config(struct rdt_resource *r)
> +int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>  {
>  	unsigned int cl_size = boot_cpu_data.x86_cache_size;
> +	u32 eax, ebx, ecx, edx;
>  	int ret;
>  
> -	r->mon_scale = boot_cpu_data.x86_cache_occ_scale;
> -	r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1;
> +	/*
> +	 * At this point, CQM LLC and one of L3 occupancy, MBM total, and
> +	 * MBM local monitoring features must be supported. So sub-leaf
> +	 * (EAX=0xf, ECX=1) contains needed information for this resource.
> +	 */
> +	cpuid_count(0xf, 1, &eax, &ebx, &ecx, &edx);
> +	r->num_rmid = ecx + 1;
> +	r->mon_scale = ebx;
>  
>  	/*
>  	 * A reasonable upper limit on the max threshold is the number

This is simpler than that:

https://lkml.kernel.org/r/20190614174959.GF198207@xxxxxxxxxxxxxxxxxxxxxxxx

Why?


-- 
Regards/Gruss,
    Boris.

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