linux-kernel - Re: [PATCH v19 01/11] perf: arm_pmuv3: Call kvm_vcpu_pmu_resync

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Message-ID: <1910b0da-68fe-4161-b7bb-f0d5ac8d5fe7@arm.com>
Date: Mon, 3 Feb 2025 09:37:31 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: "Rob Herring (Arm)" <robh@...nel.org>, Will Deacon <will@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Catalin Marinas <catalin.marinas@....com>, Jonathan Corbet <corbet@....net>,
 Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
 Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>,
 Zenghui Yu <yuzenghui@...wei.com>, James Clark <james.clark@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 kvmarm@...ts.linux.dev
Subject: Re: [PATCH v19 01/11] perf: arm_pmuv3: Call kvm_vcpu_pmu_resync_el0()
 before enabling counters



On 2/3/25 06:12, Rob Herring (Arm) wrote:
> Counting events related to setup of the PMU is not desired, but
> kvm_vcpu_pmu_resync_el0() is called just after the PMU counters have
> been enabled. Move the call to before enabling the counters.
> 
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> ---
>  drivers/perf/arm_pmuv3.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 0e360feb3432..9ebc950559c0 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -825,10 +825,10 @@ static void armv8pmu_start(struct arm_pmu *cpu_pmu)
>  	else
>  		armv8pmu_disable_user_access();
>  
> +	kvm_vcpu_pmu_resync_el0();
> +
>  	/* Enable all counters */
>  	armv8pmu_pmcr_write(armv8pmu_pmcr_read() | ARMV8_PMU_PMCR_E);
> -
> -	kvm_vcpu_pmu_resync_el0();
>  }
>  
>  static void armv8pmu_stop(struct arm_pmu *cpu_pmu)
> 

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>