linux-kernel - Re: [PATCH v2 03/23] arm64: cpufeature: Add cpucap for PMICNTR

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Message-ID: <aFYAq7GcSx4pTK9Y@linux.dev>
Date: Fri, 20 Jun 2025 17:45:31 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: Colton Lewis <coltonlewis@...gle.com>
Cc: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Russell King <linux@...linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Mark Rutland <mark.rutland@....com>, Shuah Khan <shuah@...nel.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-perf-users@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v2 03/23] arm64: cpufeature: Add cpucap for PMICNTR

On Fri, Jun 20, 2025 at 10:13:03PM +0000, Colton Lewis wrote:
> Add a cpucap for FEAT_PMUv3_PMICNTR, meaning there is a dedicated
> instruction counter as well as the cycle counter.
> 
> Signed-off-by: Colton Lewis <coltonlewis@...gle.com>

I don't see this capability being used in this series.

Thanks,
Oliver

> ---
>  arch/arm64/kernel/cpufeature.c | 7 +++++++
>  arch/arm64/tools/cpucaps       | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 278294fdc97d..85dea9714928 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -2904,6 +2904,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
>  		.matches = has_cpuid_feature,
>  		ARM64_CPUID_FIELDS(ID_AA64DFR0_EL1, HPMN0, IMP)
>  	},
> +	{
> +		.desc = "PMU Dedicated Instruction Counter",
> +		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
> +		.capability = ARM64_HAS_PMICNTR,
> +		.matches = has_cpuid_feature,
> +		ARM64_CPUID_FIELDS(ID_AA64DFR1_EL1, PMICNTR, IMP)
> +	},
>  #ifdef CONFIG_ARM64_SME
>  	{
>  		.desc = "Scalable Matrix Extension",
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 5b196ba21629..6dd72fcdd612 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -47,6 +47,7 @@ HAS_LSE_ATOMICS
>  HAS_MOPS
>  HAS_NESTED_VIRT
>  HAS_PAN
> +HAS_PMICNTR
>  HAS_PMUV3
>  HAS_S1PIE
>  HAS_S1POE
> -- 
> 2.50.0.714.g196bf9f422-goog
>