linux-kernel - Re: [PATCH v2 1/2] x86/amd: Refactor topology extension related code

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Date:   Mon, 24 Jul 2017 10:28:34 +0700
From:   Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
To:     Borislav Petkov <bp@...e.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, peterz@...radead.org,
        Yazen.Ghannam@....com
Subject: Re: [PATCH v2 1/2] x86/amd: Refactor topology extension related code

Boris,

On 7/22/17 23:12, Borislav Petkov wrote:
> On Fri, Jul 21, 2017 at 09:00:38PM -0500, Suravee Suthikulpanit wrote:
>> Refactoring in preparation for subsequent changes.
>> There is no functional change.
>>
>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
>> ---
>>  arch/x86/kernel/cpu/amd.c | 79 ++++++++++++++++++++++++++---------------------
>>  1 file changed, 44 insertions(+), 35 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
>> index bb5abe8..74d8d7c 100644
>> --- a/arch/x86/kernel/cpu/amd.c
>> +++ b/arch/x86/kernel/cpu/amd.c
>> @@ -297,54 +297,63 @@ static int nearby_node(int apicid)
>>  #endif
>>
>>  /*
>> - * Fixup core topology information for
>> - * (1) AMD multi-node processors
>> - *     Assumption: Number of cores in each internal node is the same.
>> - * (2) AMD processors supporting compute units
>> + * Get topology information via X86_FEATURE_TOPOEXT
>>   */
>> -#ifdef CONFIG_SMP
>> -static void amd_get_topology(struct cpuinfo_x86 *c)
>> +static void __get_topoext(struct cpuinfo_x86 *c)
>>  {
>> -	u8 node_id;
>> +	u32 eax, ebx, ecx, edx;
>>  	int cpu = smp_processor_id();
>>
>> -	/* get information required for multi-node processors */
>> -	if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
>> -		u32 eax, ebx, ecx, edx;
>> +	cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
>>
>> -		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
>> +	smp_num_siblings = ((ebx >> 8) & 0xff) + 1;
>>
>> -		node_id  = ecx & 0xff;
>
> When reviewers ask you about a preparatory cleanup patch, you don't
> sneak in changes in it - you *only* *move* the code so that the change
> is *absolutely* comprehensible. Ontop you do changes. Don't tell me you
> didn't know that!

I know that we should not sneak in change. I might have missed something here.

Are you referring to the part that I moved the "node_id = ecx & 0xff" from the 
top level of the function to inside the "if/else" logic where it is the only 
place that used within this new refactored __get_topoext() and there is nothing 
changed functionally? If that's really the case, I'll fix it.

Thanks,
Suravee