Re: [PATCH v1 2/2] perf/x86: Reduce is_hybrid calls and aid ellision of BUG_ON in hybrid_pmu

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

LGTM.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>


On 3/12/2026 1:48 PM, Ian Rogers wrote:
> Use the capabilities of the PMU rather than the global variable
> perf_is_hybrid to determine if a hybrid pmu has been passed to the
> main accessors. As the pmu capabilities check mirrors that in
> is_x86_pmu, the BUG_ON(!is_x86_pmu...) in hybrid_pmu can be elided as
> it is provably always false (with sufficient function inlining, common
> sub-expression elimination, etc.) in its most common uses.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> Only build tested.
> ---
>  arch/x86/events/perf_event.h | 52 +++++++++++++++++++-----------------
>  1 file changed, 28 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
> index f1123c95d174..7990d86ef233 100644
> --- a/arch/x86/events/perf_event.h
> +++ b/arch/x86/events/perf_event.h
> @@ -802,34 +802,38 @@ static __always_inline struct x86_hybrid_pmu *hybrid_pmu(struct pmu *pmu)
>  extern struct static_key_false perf_is_hybrid;
>  #define is_hybrid()		static_branch_unlikely(&perf_is_hybrid)
>  
> -#define hybrid(_pmu, _field)				\
> -(*({							\
> -	typeof(&x86_pmu._field) __Fp = &x86_pmu._field;	\
> -							\
> -	if (is_hybrid() && (_pmu))			\
> -		__Fp = &hybrid_pmu(_pmu)->_field;	\
> -							\
> -	__Fp;						\
> +
> +#define hybrid(_pmu, _field)						\
> +(*({									\
> +	typeof(&x86_pmu._field) __Fp = &x86_pmu._field;			\
> +	struct pmu *__pmu = _pmu;					\
> +									\
> +	if (__pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE)	\
> +		__Fp = &hybrid_pmu(__pmu)->_field;			\
> +									\
> +	__Fp;								\
>  }))
>  
> -#define hybrid_var(_pmu, _var)				\
> -(*({							\
> -	typeof(&_var) __Fp = &_var;			\
> -							\
> -	if (is_hybrid() && (_pmu))			\
> -		__Fp = &hybrid_pmu(_pmu)->_var;		\
> -							\
> -	__Fp;						\
> +#define hybrid_var(_pmu, _var)						\
> +(*({									\
> +	typeof(&_var) __Fp = &_var;					\
> +	struct pmu *__pmu = _pmu;					\
> +									\
> +	if (__pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE)	\
> +		__Fp = &hybrid_pmu(__pmu)->_var;			\
> +									\
> +	__Fp;								\
>  }))
>  
> -#define hybrid_bit(_pmu, _field)			\
> -({							\
> -	bool __Fp = x86_pmu._field;			\
> -							\
> -	if (is_hybrid() && (_pmu))			\
> -		__Fp = hybrid_pmu(_pmu)->_field;	\
> -							\
> -	__Fp;						\
> +#define hybrid_bit(_pmu, _field)					\
> +({									\
> +	bool __Fp = x86_pmu._field;					\
> +	struct pmu *__pmu = _pmu;					\
> +									\
> +	if (__pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE)	\
> +		__Fp = hybrid_pmu(__pmu)->_field;			\
> +									\
> +	__Fp;								\
>  })
>  
>  /*