linux-kernel - Re: [PATCH 1/4] RISC-V: KVM: Disable the kernel perf counter during configure

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Message-ID: <20250227-d64f688ee1df2811528ec2b9@orel>
Date: Thu, 27 Feb 2025 09:49:35 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Atish Patra <atishp@...osinc.com>
Cc: Anup Patel <anup@...infault.org>, Atish Patra <atishp@...shpatra.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, kvm@...r.kernel.org, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 1/4] RISC-V: KVM: Disable the kernel perf counter during
 configure

On Wed, Feb 26, 2025 at 12:25:03PM -0800, Atish Patra wrote:
> The perf event should be marked disabled during the creation as
> it is not ready to be scheduled until there is SBI PMU start call
> or config matching is called with auto start. Otherwise, event add/start
> gets called during perf_event_create_kernel_counter function.
> It will be enabled and scheduled to run via perf_event_enable during
> either the above mentioned scenario.
> 
> Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling")
> 
> Signed-off-by: Atish Patra <atishp@...osinc.com>
> ---
>  arch/riscv/kvm/vcpu_pmu.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index 2707a51b082c..78ac3216a54d 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -666,6 +666,7 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
>  		.type = etype,
>  		.size = sizeof(struct perf_event_attr),
>  		.pinned = true,
> +		.disabled = true,
>  		/*
>  		 * It should never reach here if the platform doesn't support the sscofpmf
>  		 * extension as mode filtering won't work without it.
> 
> -- 
> 2.43.0
>

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>