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

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Date:   Wed, 3 Oct 2018 09:32:58 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>
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 10/3/2018 2:10 AM, Thomas Gleixner wrote:
> 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.
> 

Sure, I will generalize the bad_spectre_microcode(), rename it to 
is_bad_intel_microcode(), and move it to 
arch\x86\kernel\cpu\microcode\intel.c.
The spectre code and perf code will share the generalized function.

Thanks,
Kan