linux-kernel - Re: [PATCH v3 05/22] KVM: Provide more information in kernel log if hardware enabling fails

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Date:   Mon, 5 Sep 2022 13:56:17 +0800
From:   Yuan Yao <yuan.yao@...ux.intel.com>
To:     isaku.yamahata@...el.com
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        isaku.yamahata@...il.com, Kai Huang <kai.huang@...el.com>,
        Chao Gao <chao.gao@...el.com>,
        Atish Patra <atishp@...shpatra.org>,
        Shaokun Zhang <zhangshaokun@...ilicon.com>,
        Qi Liu <liuqi115@...wei.com>,
        John Garry <john.garry@...wei.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Huang Ying <ying.huang@...el.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH v3 05/22] KVM: Provide more information in kernel log if
 hardware enabling fails

On Thu, Sep 01, 2022 at 07:17:40PM -0700, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <seanjc@...gle.com>
>
> Provide the name of the calling function to hardware_enable_nolock() and
> include it in the error message to provide additional information on
> exactly what path failed.
>
> Opportunistically bump the pr_info() to pr_warn(), failure to enable
> virtualization support is warn-worthy as _something_ is wrong with the
> system.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Chao Gao <chao.gao@...el.com>
> Link: https://lore.kernel.org/r/20220216031528.92558-4-chao.gao@intel.com
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>

Reviewed-by: Yuan Yao <yuan.yao@...el.com>

> ---
>  virt/kvm/kvm_main.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 4243a9541543..278eb6cc7cbe 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4991,7 +4991,7 @@ static struct miscdevice kvm_dev = {
>  	&kvm_chardev_ops,
>  };
>
> -static void hardware_enable_nolock(void *junk)
> +static void hardware_enable_nolock(void *caller_name)
>  {
>  	int cpu = raw_smp_processor_id();
>  	int r;
> @@ -5006,7 +5006,8 @@ static void hardware_enable_nolock(void *junk)
>  	if (r) {
>  		cpumask_clear_cpu(cpu, cpus_hardware_enabled);
>  		atomic_inc(&hardware_enable_failed);
> -		pr_info("kvm: enabling virtualization on CPU%d failed\n", cpu);
> +		pr_warn("kvm: enabling virtualization on CPU%d failed during %s()\n",
> +			cpu, (const char *)caller_name);
>  	}
>  }
>
> @@ -5014,7 +5015,7 @@ static int kvm_starting_cpu(unsigned int cpu)
>  {
>  	raw_spin_lock(&kvm_count_lock);
>  	if (kvm_usage_count)
> -		hardware_enable_nolock(NULL);
> +		hardware_enable_nolock((void *)__func__);
>  	raw_spin_unlock(&kvm_count_lock);
>  	return 0;
>  }
> @@ -5063,7 +5064,7 @@ static int hardware_enable_all(void)
>  	kvm_usage_count++;
>  	if (kvm_usage_count == 1) {
>  		atomic_set(&hardware_enable_failed, 0);
> -		on_each_cpu(hardware_enable_nolock, NULL, 1);
> +		on_each_cpu(hardware_enable_nolock, (void *)__func__, 1);
>
>  		if (atomic_read(&hardware_enable_failed)) {
>  			hardware_disable_all_nolock();
> @@ -5686,7 +5687,7 @@ static void kvm_resume(void)
>  {
>  	if (kvm_usage_count) {
>  		lockdep_assert_not_held(&kvm_count_lock);
> -		hardware_enable_nolock(NULL);
> +		hardware_enable_nolock((void *)__func__);
>  	}
>  }
>
> --
> 2.25.1
>