On 07.10.2025 21:38, Jason Andryuk wrote:
> On 2025-10-07 08:22, Jan Beulich wrote:
>> On 30.09.2025 01:36, Jason Andryuk wrote:
>>> On 2025-09-25 06:48, Jan Beulich wrote:
>>>> --- a/xen/arch/x86/include/asm/spec_ctrl.h
>>>> +++ b/xen/arch/x86/include/asm/spec_ctrl.h
>>>> @@ -73,7 +73,7 @@ static always_inline void spec_ctrl_new_
>>>>
>>>> /* (ab)use alternative_input() to specify clobbers. */
>>>> alternative_input("", "DO_OVERWRITE_RSB xu=%=", X86_BUG_IBPB_NO_RET,
>>>> - : "rax", "rcx");
>>>> + "i" (0) : "rax", "rcx");
>>>
>>> "i" (0) is to work around the trailing comma in alternative_input() and
>>> does nothing?
>>
>> Yes. If more such "uses" appeared, we may want to introduce some kind of
>> abstraction.
>
> Thanks for confirming.
>
> Reviewed-by: Jason Andryuk <[email protected]>
Thanks.
> Though I also wondered if just #define X86_BUG_MAX/X86_SYNTH_MAX
> combined with a BUILD_BUG_ON might be good enough. Your approach avoids
> the extra define but is more complicated. Anyway, just a thought.
How would that end up simplifying things? IOW what would the BUILD_BUG_ON()
look like that you're thinking about? After all X86_{SYNTH,BUG}_MAX aren't
meaningfully different from X86_NR_{SYNTH,BUG}.
Jan
