linux-kernel - Re: [PATCH v3 1/2] x86/mm: rename the confusing local variable in early_memremap_is_setup

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Message-ID: <8c81835b-97fe-a0b3-a860-0bbd5c0341f6@amd.com>
Date: Wed, 30 Oct 2024 07:49:05 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Baoquan He <bhe@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, dyoung@...hat.com, daniel.kiper@...cle.com,
 noodles@...com, lijiang@...hat.com, kexec@...ts.infradead.org, x86@...nel.org
Subject: Re: [PATCH v3 1/2] x86/mm: rename the confusing local variable in
 early_memremap_is_setup_data()

On 10/29/24 19:53, Baoquan He wrote:
> On 10/29/24 at 07:11pm, Borislav Petkov wrote:
>> On Wed, Sep 11, 2024 at 04:16:14PM +0800, Baoquan He wrote:
>>> In function early_memremap_is_setup_data(), parameter 'size' passed has
>>> the same name as the local variable inside the while loop. That
>>> confuses people who sometime mix up them when reading code.
>>>
>>> Here rename the local variable 'size' inside while loop to 'sd_size'.
>>>
>>> And also add one local variable 'sd_size' likewise in function
>>> memremap_is_setup_data() to simplify code. In later patch, this can also
>>> be used.
>>>
>>> Signed-off-by: Baoquan He <bhe@...hat.com>
>>> Acked-by: Tom Lendacky <thomas.lendacky@....com>
>>> ---
>>>  arch/x86/mm/ioremap.c | 18 +++++++++++-------
>>>  1 file changed, 11 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
>>> index aa7d279321ea..f1ee8822ddf1 100644
>>> --- a/arch/x86/mm/ioremap.c
>>> +++ b/arch/x86/mm/ioremap.c
>>> @@ -640,7 +640,7 @@ static bool memremap_is_setup_data(resource_size_t phys_addr,
>>
>> Huh?
> 
> Thanks for looking into this.
> 
> I ever doubted this, guess it could use the unused 'size' to avoid
> warning? Noticed Tom introduced it at the beginning. It's better idea to
> remove it if it's useless.
> 
> commit 8f716c9b5febf6ed0f5fedb7c9407cd0c25b2796
> Author: Tom Lendacky <thomas.lendacky@....com>
> Date:   Mon Jul 17 16:10:16 2017 -0500
> 
>     x86/mm: Add support to access boot related data in the clear
> 
> Hi Tom,
> 
> Can you help check and tell your intention why the argument 'size' is
> added into early_memremap_is_setup_data() and memremap_is_setup_data().

That was a long time ago... I probably used it while I was developing the
support and then never removed it in the final version where it wasn't used.

Thanks,
Tom

> 
> Thanks
> Baoquan
> 
>>
>> ---
>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
>> index 70b02fc61d93..e461d8e26871 100644
>> --- a/arch/x86/mm/ioremap.c
>> +++ b/arch/x86/mm/ioremap.c
>> @@ -632,8 +632,7 @@ static bool memremap_is_efi_data(resource_size_t phys_addr,
>>   * Examine the physical address to determine if it is boot data by checking
>>   * it against the boot params setup_data chain.
>>   */
>> -static bool memremap_is_setup_data(resource_size_t phys_addr,
>> -				   unsigned long size)
>> +static bool memremap_is_setup_data(resource_size_t phys_addr)
>>  {
>>  	struct setup_indirect *indirect;
>>  	struct setup_data *data;
>> @@ -769,7 +768,7 @@ bool arch_memremap_can_ram_remap(resource_size_t phys_addr, unsigned long size,
>>  		return false;
>>  
>>  	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
>> -		if (memremap_is_setup_data(phys_addr, size) ||
>> +		if (memremap_is_setup_data(phys_addr) ||
>>  		    memremap_is_efi_data(phys_addr, size))
>>  			return false;
>>  	}
>>
>> -- 
>> Regards/Gruss,
>>     Boris.
>>
>> https://people.kernel.org/tglx/notes-about-netiquette
>>
> 
>