linux-kernel - Re: [PATCH v2 3/3] LoongArch: Add paravirt preempt print prompt

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Message-ID: <CAAhV-H5xA_QcRXJsiW929pQ3zPw-5BqgbGW6K5Qy9sa3ofH+9g@mail.gmail.com>
Date: Mon, 24 Nov 2025 14:33:20 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Bibo Mao <maobibo@...ngson.cn>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Juergen Gross <jgross@...e.com>, 
	Ajay Kaher <ajay.kaher@...adcom.com>, Alexey Makhalov <alexey.makhalov@...adcom.com>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, WANG Xuerui <kernel@...0n.name>, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	virtualization@...ts.linux.dev, x86@...nel.org
Subject: Re: [PATCH v2 3/3] LoongArch: Add paravirt preempt print prompt

Hi, Bibo,

On Mon, Nov 24, 2025 at 11:54 AM Bibo Mao <maobibo@...ngson.cn> wrote:
>
> Add paravirt preempt print prompt together with steal timer information,
> so that it is easy to check whether paravirt preempt feature is enabled
> or not.
>
> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
> ---
>  arch/loongarch/kernel/paravirt.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c
> index d4163679adc4..ffe1cf284c41 100644
> --- a/arch/loongarch/kernel/paravirt.c
> +++ b/arch/loongarch/kernel/paravirt.c
> @@ -300,6 +300,7 @@ static struct notifier_block pv_reboot_nb = {
>  int __init pv_time_init(void)
>  {
>         int r;
> +       bool pv_preempted = false;
>
>         if (!kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
>                 return 0;
> @@ -322,8 +323,10 @@ int __init pv_time_init(void)
>                 return r;
>         }
>
> -       if (kvm_para_has_feature(KVM_FEATURE_PREEMPT))
> +       if (kvm_para_has_feature(KVM_FEATURE_PREEMPT)) {
>                 static_branch_enable(&virt_preempt_key);
> +               pv_preempted = true;
> +       }
>  #endif
>
>         static_call_update(pv_steal_clock, paravt_steal_clock);
> @@ -334,7 +337,10 @@ int __init pv_time_init(void)
>                 static_key_slow_inc(&paravirt_steal_rq_enabled);
>  #endif
>
> -       pr_info("Using paravirt steal-time\n");
> +       if (pv_preempted)
No pv_preempted needed, you can just use
static_key_enabled(&virt_preempt_key) and merge this patch to Patch-2.


Huacai

> +               pr_info("Using paravirt steal-time with preempt hint enabled\n");
> +       else
> +               pr_info("Using paravirt steal-time with preempt hint disabled\n");
>
>         return 0;
>  }
> --
> 2.39.3
>