linux-kernel - Re: [PATCH] perf/x86/intel: Add counter freezing quirk for Goldmont

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Date:   Wed, 3 Oct 2018 08:10:31 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Kan Liang <kan.liang@...ux.intel.com>
cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, eranian@...gle.com,
        ak@...ux.intel.com, alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH] perf/x86/intel: Add counter freezing quirk for
 Goldmont

On Tue, 2 Oct 2018, kan.liang@...ux.intel.com wrote:
> +static bool intel_atom_v4_counter_freezing_broken(int cpu)
>  {
>  	u32 rev = UINT_MAX; /* default to broken for unknown stepping */
>  
> -	switch (cpu_data(cpu).x86_stepping) {
> -	case 1:
> -		rev = 0x28;
> +	switch (cpu_data(cpu).x86_model) {
> +	case INTEL_FAM6_ATOM_GOLDMONT:
> +		switch (cpu_data(cpu).x86_stepping) {
> +		case 2:
> +			rev = 0xe;
> +			break;
> +		case 9:
> +			rev = 0x2e;
> +			break;
> +		case 10:
> +			rev = 0x8;
> +			break;
> +		}
>  		break;
> -	case 8:
> -		rev = 0x6;
> +
> +	case INTEL_FAM6_ATOM_GOLDMONT_X:
> +		switch (cpu_data(cpu).x86_stepping) {
> +		case 1:
> +			rev = 0x1a;
> +			break;
> +		}
>  		break;
> +
> +	case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
> +		switch (cpu_data(cpu).x86_stepping) {
> +		case 1:
> +			rev = 0x28;
> +			break;
> +		case 8:
> +			rev = 0x6;
> +			break;
> +		}
>  	}
>  
>  	return (cpu_data(cpu).microcode < rev);

There is another variant of model/stepping micro code verification code in
intel_snb_pebs_broken(). Can we please make this table based and use a
common function? That's certainly not the last quirk we're going to have.

We already have a table based variant of ucode checking in
bad_spectre_microcode(). It's trivial enough to generalize that.

Thanks,

	tglx