linux-kernel - Re: [Xen-devel] [PATCH] xen/x86: Don't BUG on CPU0 offlining

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Date:   Wed, 28 Jun 2017 11:44:24 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     xen-devel@...ts.xenproject.org, Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH] xen/x86: Don't BUG on CPU0 offlining

On Mon, Jun 26, 2017 at 06:39:30PM +0200, Vitaly Kuznetsov wrote:
> CONFIG_BOOTPARAM_HOTPLUG_CPU0 allows to offline CPU0 but Xen HVM guests
> BUG() in xen_teardown_timer(). Remove the BUG_ON(), this is probably a
> leftover from ancient times when CPU0 hotplug was impossible, it works
> just fine for HVM.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>


Perhaps:

BUG_ON(cpu == 0 && xen_pv_domain()); 

?

> ---
> - CPU0 hotplug is currently broken on x86, see
>   https://lkml.org/lkml/2017/6/26/529
> ---
>  arch/x86/xen/time.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
> index a1895a8..1ecb05d 100644
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -309,7 +309,6 @@ static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
>  void xen_teardown_timer(int cpu)
>  {
>  	struct clock_event_device *evt;
> -	BUG_ON(cpu == 0);
>  	evt = &per_cpu(xen_clock_events, cpu).evt;
>  
>  	if (evt->irq >= 0) {
> -- 
> 2.9.4
> 
> 
> _______________________________________________
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