Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path

[Borislav Petkov]

On Tue, Aug 29, 2017 at 11:46:37AM +0000, Yang Zhang wrote:
> Add poll in do_idle. For UP VM, if there are running task, it will not
> goes into idle path, so we only enable poll in SMP VM.
> 
> Signed-off-by: Yang Zhang <yang.zhang.wz@xxxxxxxxx>
> Signed-off-by: Quan Xu <quan.xu0@xxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Kyle Huey <me@xxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  arch/x86/kernel/process.c | 7 +++++++
>  kernel/sched/idle.c       | 2 ++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 3ca1980..def4113 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -332,6 +332,13 @@ void arch_cpu_idle(void)
>  	x86_idle();
>  }
>  
> +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT)
> +void arch_cpu_idle_poll(void)
> +{
> +	paravirt_idle_poll();
> +}
> +#endif

So this will get called on any system which has CONFIG_PARAVIRT enabled
*even* if they're not running any guests.

Huh?

-- 
Regards/Gruss,
    Boris.

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