Re: [PATCH 2/5] x86/asm: Split __wr{fs,gs}base() out of write_{fs,gs}_base()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 10/09/2020 15:47, Jan Beulich wrote:
> On 09.09.2020 11:59, Andrew Cooper wrote:
>> To match the read side which is already split out.  A future change will want
>> to use them.
>>
>> No functional change.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> Of course ...
>
>> --- a/xen/include/asm-x86/msr.h
>> +++ b/xen/include/asm-x86/msr.h
>> @@ -156,6 +156,24 @@ static inline unsigned long __rdgsbase(void)
>>      return base;
>>  }
>>  
>> +static inline void __wrfsbase(unsigned long base)
>> +{
>> +#ifdef HAVE_AS_FSGSBASE
>> +    asm volatile ( "wrfsbase %0" :: "r" (base) );
>> +#else
>> +    asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) );
>> +#endif
>> +}
>> +
>> +static inline void __wrgsbase(unsigned long base)
>> +{
>> +#ifdef HAVE_AS_FSGSBASE
>> +    asm volatile ( "wrgsbase %0" :: "r" (base) );
>> +#else
>> +    asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) );
>> +#endif
>> +}
> ... I'd have preferred if you had used just a single leading
> underscore, despite realizing this would introduce an inconsistency
> with the read sides.

You're welcome to change them if you wish.

As always, I value consistency far far higher than arbitrary rules which
don't impact us in practice.

~Andrew