linux-kernel - Re: [PATCH 14/18] KVM: x86/pmu: Drop redundant check on PMC being globally enabled for emulation

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Message-ID: <c92d0904-45de-424a-ad36-172e8e38d15b@linux.intel.com>
Date: Wed, 6 Aug 2025 15:32:06 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Xin Li
 <xin@...or.com>, Sandipan Das <sandipan.das@....com>
Subject: Re: [PATCH 14/18] KVM: x86/pmu: Drop redundant check on PMC being
 globally enabled for emulation


On 8/6/2025 3:05 AM, Sean Christopherson wrote:
> When triggering PMC events in response to emulation, drop the redundant
> checks on a PMC being globally and locally enabled, as the passed in bitmap
> contains only PMCs that are locally enabled (and counting the right event),
> and the local copy of the bitmap has already been masked with global_ctrl.
>
> No true functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/pmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index a495ab5d0556..bdcd9c6f0ec0 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -969,7 +969,7 @@ static void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu,
>  		return;
>  
>  	kvm_for_each_pmc(pmu, pmc, i, bitmap) {
> -		if (!pmc_is_globally_enabled(pmc) || !pmc_is_locally_enabled(pmc) ||
> +		if (!pmc_is_locally_enabled(pmc) ||
>  		    !check_pmu_event_filter(pmc) || !cpl_is_matched(pmc))
>  			continue;
>  

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