linux-kernel - Re: [PATCH v6 2/2] x86/apic: x2apic write eoi msr notrace

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Date:   Fri, 28 Oct 2016 18:42:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v6 2/2] x86/apic: x2apic write eoi msr notrace

On Thu, Oct 27, 2016 at 12:38:42PM +0800, Wanpeng Li wrote:

...

> This patch converts x2apic write eoi msr to notrace to avoid the debug 
> codes splash and reverts irq_enter/irq_exit dance to avoid to make a very 
> frequent interrupt slower because of debug code.
> 
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Mike Galbraith <efault@....de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
> ---

...

> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index edbbfc8..d230513 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -308,7 +308,7 @@ static void kvm_register_steal_time(void)
>  
>  static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
>  
> -static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
> +notrace static void kvm_guest_apic_eoi_write(u32 reg, u32 val)

WARNING: storage class should be at the beginning of the declaration
#107: FILE: arch/x86/kernel/kvm.c:311:
+notrace static void kvm_guest_apic_eoi_write(u32 reg, u32 val)

Make sure you integrate checkpatch.pl in your patches creating workflow...

-- 
Regards/Gruss,
    Boris.

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