Re: [PATCH 4/9] KVM: arm64: PMU: Add counter_index_to_*reg() helpers

From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, kernel-team@android.com,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/9] KVM: arm64: PMU: Add counter_index_to_*reg() helpers
Date: Wed, 10 Aug 2022 02:17:52 -0500	[thread overview]
Message-ID: <YvNboA7nla0NcKwa@google.com> (raw)
In-Reply-To: <20220805135813.2102034-5-maz@kernel.org>

On Fri, Aug 05, 2022 at 02:58:08PM +0100, Marc Zyngier wrote:
> In order to reduce the boilerplate code, add two helpers returning
> the counter register index (resp. the event register) in the vcpu
> register file from the counter index.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

> ---
>  arch/arm64/kvm/pmu-emul.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
> index 0ab6f59f433c..9be485d23416 100644
> --- a/arch/arm64/kvm/pmu-emul.c
> +++ b/arch/arm64/kvm/pmu-emul.c
> @@ -75,6 +75,16 @@ static struct kvm_vcpu *kvm_pmc_to_vcpu(struct kvm_pmc *pmc)
>  	return container_of(vcpu_arch, struct kvm_vcpu, arch);
>  }
>  
> +static u32 counter_index_to_reg(u64 idx)
> +{
> +	return (idx == ARMV8_PMU_CYCLE_IDX) ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + idx;
> +}
> +
> +static u32 counter_index_to_evtreg(u64 idx)
> +{
> +	return (idx == ARMV8_PMU_CYCLE_IDX) ? PMCCFILTR_EL0 : PMEVTYPER0_EL0 + idx;
> +}
> +
>  /**
>   * kvm_pmu_get_counter_value - get PMU counter value
>   * @vcpu: The vcpu pointer
> @@ -89,8 +99,7 @@ u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx)
>  	if (!kvm_vcpu_has_pmu(vcpu))
>  		return 0;
>  
> -	reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
> -		? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx;
> +	reg = counter_index_to_reg(select_idx);
>  	counter = __vcpu_sys_reg(vcpu, reg);
>  
>  	/*
> @@ -120,8 +129,7 @@ void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val)
>  	if (!kvm_vcpu_has_pmu(vcpu))
>  		return;
>  
> -	reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
> -	      ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_idx;
> +	reg = counter_index_to_reg(select_idx);
>  	__vcpu_sys_reg(vcpu, reg) += (s64)val - kvm_pmu_get_counter_value(vcpu, select_idx);
>  
>  	/* Recreate the perf event to reflect the updated sample_period */
> @@ -156,10 +164,7 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
>  
>  	counter = kvm_pmu_get_counter_value(vcpu, pmc->idx);
>  
> -	if (pmc->idx == ARMV8_PMU_CYCLE_IDX)
> -		reg = PMCCNTR_EL0;
> -	else
> -		reg = PMEVCNTR0_EL0 + pmc->idx;
> +	reg = counter_index_to_reg(pmc->idx);
>  
>  	if (!kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
>  		counter = lower_32_bits(counter);
> @@ -540,8 +545,7 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
>  	struct perf_event_attr attr;
>  	u64 eventsel, counter, reg, data;
>  
> -	reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
> -	      ? PMCCFILTR_EL0 : PMEVTYPER0_EL0 + pmc->idx;
> +	reg = counter_index_to_evtreg(select_idx);
>  	data = __vcpu_sys_reg(vcpu, reg);
>  
>  	kvm_pmu_stop_counter(vcpu, pmc);
> @@ -627,8 +631,7 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>  	mask &= ~ARMV8_PMU_EVTYPE_EVENT;
>  	mask |= kvm_pmu_event_mask(vcpu->kvm);
>  
> -	reg = (select_idx == ARMV8_PMU_CYCLE_IDX)
> -	      ? PMCCFILTR_EL0 : PMEVTYPER0_EL0 + select_idx;
> +	reg = counter_index_to_evtreg(select_idx);
>  
>  	__vcpu_sys_reg(vcpu, reg) = data & mask;
>  
> -- 
> 2.34.1
> 
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