On 22.04.2024 15:35, Roger Pau Monné wrote:
> On Fri, Apr 19, 2024 at 08:25:00AM +0200, Jan Beulich wrote:
>> On 18.04.2024 17:52, Roger Pau Monne wrote:
>>> --- a/xen/arch/x86/include/asm/cpufeature.h
>>> +++ b/xen/arch/x86/include/asm/cpufeature.h
>>> @@ -235,9 +235,6 @@ static inline bool boot_cpu_has(unsigned int feat)
>>>  #define cpu_bug_fpu_ptrs        boot_cpu_has(X86_BUG_FPU_PTRS)
>>>  #define cpu_bug_null_seg        boot_cpu_has(X86_BUG_NULL_SEG)
>>>  
>>> -#define cpu_has_bhb_seq        (boot_cpu_has(X86_SPEC_BHB_TSX) ||       \
>>> -                                boot_cpu_has(X86_SPEC_BHB_LOOPS))
>>
>> Might be worth also mentioning in the description that this construct was
>> lacking use of X86_SPEC_BHB_LOOPS_LONG (might even warrant a 2nd Fixes:
>> tag).
> 
> Heh, no, X86_SPEC_BHB_LOOPS_LONG is added in addition to
> X86_SPEC_BHB_LOOPS.   When using long loops we have both
> X86_SPEC_BHB_LOOPS and X86_SPEC_BHB_LOOPS_LONG set (I know it's
> confusing, I was also confused the first time and asked Andrew the
> same question).  See the fallthrough in bhi_calculations().

Oh, I see.

Andrew: This is a very good example of the separating blank line being
misleading when fall-through is intended.

Jan

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