linux-kernel - Re: [PATCH 4/5] KVM: x86/pmu: Reorder functions to reduce unnecessary declarations

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Message-ID: <ZG5+Ud26J0Ll7g0w@google.com>
Date:   Wed, 24 May 2023 14:14:57 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Ravi Bangoria <ravi.bangoria@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] KVM: x86/pmu: Reorder functions to reduce unnecessary declarations

On Fri, Mar 10, 2023, Like Xu wrote:
> From: Like Xu <likexu@...cent.com>
> 
> Considering that more emulations are deferred to kvm_pmu_handle_event(),
> moving it to the end of pmu.c makes it easier to call previous functions,
> instead of just piling up the function declarations to make compiler green.

kvm_pmu_handle_event() is globally visible, moving it around changes nothing.

As for using it in kvm_mark_pmc_is_quirky(), explicitly state the direct
motivation for moving kvm_pmu_request_counter_reprogram(), i.e. that it's being
hoisted above pmc_read_counter() for use in a future patch.  Using abstract
language might sound pretty and dramatic, but it's really not helpful for reviewers.

> diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
> index db4262fe8814..a47b579667c6 100644
> --- a/arch/x86/kvm/pmu.h
> +++ b/arch/x86/kvm/pmu.h
> @@ -48,6 +48,12 @@ static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
>  	return pmu->counter_bitmask[pmc->type];
>  }
>  
> +static inline void kvm_pmu_request_counter_reprogram(struct kvm_pmc *pmc)
> +{
> +	set_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);
> +	kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
> +}
> +
>  static inline u64 pmc_read_counter(struct kvm_pmc *pmc)
>  {
>  	u64 counter, enabled, running;
> @@ -183,12 +189,6 @@ static inline void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops)
>  					     KVM_PMC_MAX_FIXED);
>  }
>  
> -static inline void kvm_pmu_request_counter_reprogram(struct kvm_pmc *pmc)
> -{
> -	set_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);
> -	kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
> -}
> -
>  static inline bool pebs_is_enabled(struct kvm_pmc *pmc)
>  {
>  	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
> -- 
> 2.39.2
>