Re: [PATCH v2 1/2] platforms/x86: Add AMD system management interface

[Carlos Bilbao <carlos.bilbao@amd.com>]

Hello,

On 2/3/2022 9:48 AM, Nathan Fontenot wrote:
> On 2/3/22 06:04, Naveen Krishna Chatradhi wrote:
>> From: Suma Hegde <suma.hegde@amd.com>
>>
>> (...)
>> +static bool check_model_support(void)
>> +{
>> +	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD ||
>> +	    boot_cpu_data.x86 != 0x19)
> 
> Check for boot_cpu_data.x86 < 0x19, lets avoid having to do driver updates any
> time future families support HSMP.
> 
>> +		return false;
>> +
>> +	switch (boot_cpu_data.x86_model) {
>> +	case 0x00 ... 0x1f:
>> +	case 0x30 ... 0x3f:
>> +		return true;
>> +	default:
>> +		return false;
>> +	}
> 
> I don't think the model check here is necessary. Adding a model check will only
> add driver updates for any new models.
> 
> HSMP is only supported on f19h so we do want to keep that. For the different
> models that may not support HSMP, the call to hsmp_test() in the init routine
> will fail if HSMP isn't supported.

So, for this I think Naveen was trying to avoid people with Fam19th client processors 
complaining about errors in HSMP and filing bugs. You are equally right pointing out 
that updating this in the future would be inconvenient. Personally, if I put myself in 
the shoes of an owner of one of those systems, I would be a bit disappointed to run HSMP
and just fail. So, maybe a solution in the middle would be to remove the model-checking code 
but also include a warning/clarification in the documentation. 

Thanks,
Carlos.