linux-kernel - Re: [PATCH][tip] x86/paravirt: Make the virt_spin_lock_key setup after jump_label

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Date:   Fri, 27 Oct 2017 19:27:33 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Dou Liyang <douly.fnst@...fujitsu.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        xen-devel@...ts.xenproject.org
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        boris.ostrovsky@...cle.com, bp@...e.de, luto@...nel.org,
        vkuznets@...hat.com
Subject: Re: [PATCH][tip] x86/paravirt: Make the virt_spin_lock_key setup
 after jump_label_init()

On 27/10/17 18:02, Dou Liyang wrote:
> Commit:
> 
>   9043442b43b1 ("locking/paravirt: Use new static key for controlling
>   call of virt_spin_lock()")
> 
> set the static virt_spin_lock_key to a value before jump_label_init()
> has been called, which will result in a WARN().
> 
> Move the native_pv_lock_init() into xx_smp_prepare_cpus(). Make the
> setup later to avoid the WARN().
> 
> Reported-by: Juergen Gross <jgross@...e.com>
> Suggested-by: Juergen Gross <jgross@...e.com>
> Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
> ---
>  arch/x86/kernel/smpboot.c | 3 ++-
>  arch/x86/xen/smp_pv.c     | 2 ++
>  arch/x86/xen/spinlock.c   | 6 ++++--
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index aed1460..6b1335a 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1323,6 +1323,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
>  	pr_info("CPU0: ");
>  	print_cpu_info(&cpu_data(0));
>  
> +	native_pv_lock_init();
> +
>  	uv_system_init();
>  
>  	set_mtrr_aps_delayed_init();
> @@ -1350,7 +1352,6 @@ void __init native_smp_prepare_boot_cpu(void)
>  	/* already set me in cpu_online_mask in boot_cpu_init() */
>  	cpumask_set_cpu(me, cpu_callout_mask);
>  	cpu_set_state_online(me);
> -	native_pv_lock_init();
>  }
>  
>  void __init native_smp_cpus_done(unsigned int max_cpus)
> diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
> index 5147140..570b2bc 100644
> --- a/arch/x86/xen/smp_pv.c
> +++ b/arch/x86/xen/smp_pv.c
> @@ -236,6 +236,8 @@ static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
>  		xen_raw_printk(m);
>  		panic(m);
>  	}
> +	native_pv_lock_init();
> +

This can be removed, as for a Xen domain native_pv_lock_init() is a nop.

With that:

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen