linux-kernel - Re: [Xen-devel] [PATCH] ARM: xen: only set pm function ptrs for Xen guests

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Date:	Wed, 28 Aug 2013 13:03:27 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Julien Grall <julien.grall@...aro.org>
Cc:	xen-devel@...ts.xensource.com,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Rob Herring <rob.herring@...xeda.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>
Subject: Re: [Xen-devel] [PATCH] ARM: xen: only set pm function ptrs for Xen guests

On Wed, Aug 28, 2013 at 11:32 AM, Julien Grall <julien.grall@...aro.org> wrote:
> On 08/28/2013 05:19 PM, Rob Herring wrote:
>> From: Rob Herring <rob.herring@...xeda.com>
>>
>> xen_pm_init was unconditionally setting pm_power_off and arm_pm_restart
>> function pointers. This breaks multi-platform kernels. Move this
>> initialization into xen_guest_init, so it is conditional on running as a
>> Xen guest.
>>
>> Cc: Stefano Stabellini <stefano.stabellini@...citrix.com>
>> Signed-off-by: Rob Herring <rob.herring@...xeda.com>
>> ---
>> This breaks reset and poweroff for Midway when Xen is enabled. This
>> should go into 3.11 or stable.
>> Rob
>>
>>  arch/arm/xen/enlighten.c | 12 +++---------
>>  1 file changed, 3 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
>> index 8a6295c..fa86452 100644
>> --- a/arch/arm/xen/enlighten.c
>> +++ b/arch/arm/xen/enlighten.c
>> @@ -263,6 +263,9 @@ static int __init xen_guest_init(void)
>>       if (xen_vcpu_info == NULL)
>>               return -ENOMEM;
>>
>> +     pm_power_off = xen_power_off;
>> +     arm_pm_restart = xen_restart;
>> +
>
> I think it's too early to set pm callbacks. If Linux is running as dom0,
> xen needs to overwrite the power management callback. Otherwise, dom0
> could shutdown/restart the whole platform, that is annoying.
> For instance, on the versatile express, the power management callback
> are set very late (ie during driver initialization).
>
> pm callbacks should be updated by a late initcall and check if xen is
> enabled.
>
>>       gnttab_init();
>>       if (!xen_initial_domain())
>>               xenbus_probe(NULL);
>> @@ -271,15 +274,6 @@ static int __init xen_guest_init(void)
>>  }
>>  core_initcall(xen_guest_init);
>>
>> -static int __init xen_pm_init(void)
>> -{
>> -     pm_power_off = xen_power_off;
>> -     arm_pm_restart = xen_restart;
>> -
>> -     return 0;
>> -}
>> -subsys_initcall(xen_pm_init);
>> -
>>  static irqreturn_t xen_arm_callback(int irq, void *arg)
>>  {
>>       xen_hvm_evtchn_do_upcall();
>>
>
>
> --
> Julien Grall
--
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