linux-kernel - Re: [PATCH v2] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed

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Message-ID: <3d1d84a0-7c63-e470-a1d1-b32f56e52f74@redhat.com>
Date:   Thu, 18 Jul 2019 15:52:53 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Like Xu <like.xu@...ux.intel.com>, Avi Kivity <avi@...lladb.com>
Cc:     Joe Perches <joe@...ches.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] KVM: x86/vPMU: refine kvm_pmu err msg when event
 creation failed

On 18/07/19 07:35, Like Xu wrote:
> If a perf_event creation fails due to any reason of the host perf
> subsystem, it has no chance to log the corresponding event for guest
> which may cause abnormal sampling data in guest result. In debug mode,
> this message helps to understand the state of vPMC and we may not
> limit the number of occurrences but not in a spamming style.
> 
> Suggested-by: Joe Perches <joe@...ches.com>
> Signed-off-by: Like Xu <like.xu@...ux.intel.com>
> ---
>  arch/x86/kvm/pmu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index aa5a2597305a..cedaa01ceb6f 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -131,8 +131,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
>  						 intr ? kvm_perf_overflow_intr :
>  						 kvm_perf_overflow, pmc);
>  	if (IS_ERR(event)) {
> -		printk_once("kvm_pmu: event creation failed %ld\n",
> -			    PTR_ERR(event));
> +		pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",
> +			    PTR_ERR(event), pmc->idx);
>  		return;
>  	}
>  
> 

Queued, thanks.

Paolo