Re: [PATCH v2 2/2] x86/xstate: also use alternative asm on xsave side

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 03/02/16 13:34, Jan Beulich wrote:
>>>> On 03.02.16 at 14:26, <andrew.cooper3@citrix.com> wrote:
>> On 03/02/16 12:39, Jan Beulich wrote:
>>> --- a/xen/arch/x86/xstate.c
>>> +++ b/xen/arch/x86/xstate.c
>>> @@ -250,27 +250,29 @@ void xsave(struct vcpu *v, uint64_t mask
>>>      uint32_t hmask = mask >> 32;
>>>      uint32_t lmask = mask;
>>>      int word_size = mask & XSTATE_FP ? (cpu_has_fpu_sel ? 8 : 0) : -1;
>>> +#define XSAVE(pfx) \
>>> +        alternative_io_3(".byte " pfx "0x0f,0xae,0x27\n", \
>>> +                         ".byte " pfx "0x0f,0xae,0x37\n", \
>>> +                         X86_FEATURE_XSAVEOPT, \
>>> +                         ".byte " pfx "0x0f,0xc7,0x27\n", \
>>> +                         X86_FEATURE_XSAVEC, \
>>> +                         ".byte " pfx "0x0f,0xc7,0x2f\n", \
>>> +                         X86_FEATURE_XSAVES, \
>> Given that the options are a little out of order and using raw bytes,
>> would you mind annotating the lines with the operations. e.g.
>>
>> +        alternative_io_3(".byte " pfx "0x0f,0xae,0x27\n", /* xsave */ \
>> +                         ".byte " pfx "0x0f,0xae,0x37\n", /* xsaveopt */ \
>> +                         X86_FEATURE_XSAVEOPT, \
>> +                         ".byte " pfx "0x0f,0xc7,0x27\n", /* xsavec */ \
>> +                         X86_FEATURE_XSAVEC, \
>> +                         ".byte " pfx "0x0f,0xc7,0x2f\n", /* xsaves */ \
>> +                         X86_FEATURE_XSAVES, \
>>
>> IMO, this is somewhat clearer to read.
> Okay, since I had been considering this too, I've just done so.
>
>> Otherwise,
>>
>> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Thanks, Jan

On further thoughts, it would be nice to annotate the XRSTOR() side as well.

~Andrew