linux-kernel - Re: [Xen-devel] [PATCH v8 10/13] x86/xen: Bypass intr mode setup in enlighten

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Date:   Mon, 28 Aug 2017 06:25:54 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Dou Liyang <douly.fnst@...fujitsu.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de
Cc:     indou.takao@...fujitsu.com, xen-devel@...ts.xenproject.org,
        bhe@...hat.com, rjw@...ysocki.net, bp@...en8.de, hpa@...or.com,
        izumi.taku@...fujitsu.com, boris.ostrovsky@...cle.com,
        mingo@...nel.org
Subject: Re: [Xen-devel] [PATCH v8 10/13] x86/xen: Bypass intr mode setup in
 enlighten_pv system

On 28/08/17 05:20, Dou Liyang wrote:
> XEN PV overrides smp_prepare_cpus(). xen_pv_smp_prepare_cpus()
> initializes interrupts in the XEN PV specific way and does not invoke
> native_smp_prepare_cpus(). As a consequence, x86_init.intr_mode_init() is
> not invoked either.
> 
> The invocation of x86_init.intr_mode_init() will be moved from
> native_smp_prepare_cpus() in a follow up patch to solve <INSERT
> REASON/PROBLEM>.

Can you be a little bit more precise here, please? :-)

> That move would cause the invocation of x86_init.intr_mode_init() for XEN
> PV platforms. To prevent that, override the default x86_init.
> intr_mode_init() callback with a noop().
> 
> [Rewrited by Thomas Gleixner <tglx@...utronix.de>]
> 
> Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
> Cc: xen-devel@...ts.xenproject.org
> Cc: boris.ostrovsky@...cle.com

On which tree does this apply? Would be nice to get a hint against which
source this can be reviewed.


Juergen

> ---
>  arch/x86/xen/enlighten_pv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 811e4dd..07147dd 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -1250,6 +1250,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
>  	x86_platform.get_nmi_reason = xen_get_nmi_reason;
>  
>  	x86_init.resources.memory_setup = xen_memory_setup;
> +	x86_init.irqs.intr_mode_init	= x86_init_noop;
>  	x86_init.oem.arch_setup = xen_arch_setup;
>  	x86_init.oem.banner = xen_banner;
>  
>