WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] bogus HPET initialization order on x86

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: RE: [Xen-devel] bogus HPET initialization order on x86
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Fri, 11 Mar 2011 18:16:41 +0800
Accept-language: zh-CN, en-US
Acceptlanguage: zh-CN, en-US
Cc: "keir.xen@xxxxxxxxx" <keir.xen@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Yu, Ke" <ke.yu@xxxxxxxxx>, "Wei, Gang" <gang.wei@xxxxxxxxx>
Delivery-date: Fri, 11 Mar 2011 02:18:06 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4D79EC8C0200007800035C08@xxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <4D7933EE020000780006C4B6@xxxxxxxxxxxxxxxxxx> <F26D193E20BBDC42A43B611D1BDEDE7125F7800936@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4D79EC8C0200007800035C08@xxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcvfxvXZjA7eog86Qney/7Bho4kbewACrhqg
Thread-topic: [Xen-devel] bogus HPET initialization order on x86
Jan Beulich wrote on 2011-03-11:
>>>> On 11.03.11 at 03:43, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote:
>> Further, it would be better if we could disable PIT interrupt before
>> calling hpet_broadcast_init(), and re-enable PIT interrupt only
>> while PIT broadcast is needed.
> 
> But I'll leave that part to you.

I will send a patch for this.

>>> The non-legacy interrupts also get fully set up before Dom0 boots -
>>> I don't think I saw anything that specifically enables these
>>> interrupts upon arrival of some ACPI data from Dom0.
>> 
>> The non-legacy interrupts will only come after some hpet channels
>> was programmed. Before hypervisor got ACPI data from Dom0 and be
>> capable to enter deep C states, hpet channels were not programmed.
> 
> Could you point out *where* this happens? My reading of the code is
> that all channels get set fully up during hpet_broadcast_init()
> (->hpet_fsb_cap_lookup() ->hpet_assign_irq() ->hpet_setup_msi_irq()
> ->request_irq()). The only thing done later are adjustments of the
> interrupts' affinities.

What you read is just the configuration of the hpet interrupt. The hpet 
programming is happen in below places:
1. hpet_broadcast_enter()->reprogram_hpet_evt_channel()
2. handle_hpet_broadcast()->reprogram_hpet_evt_channel()

So the hpet interrupt should come after the first calling to 
hpet_broadcast_enter() (i.e. lapic_timer_off()).

> 
>>>> Do I miss any other cases? If not, I will cook a patch to add the
>>>> required comments along with pulling spinlock/rwlock
>>>> initialization before .event_handler settings.
>>> 
>>> Yes, please, though I could also fold this in my bigger cleanup
>>> patch (properly separating init a resume paths) if I still didn't
>>> understand some aspect of it and this turns out a mere cleanup.
>> 
>> Oh, if you like, you can definitely include these change in your
>> cleanup patch. It is your finding. You deserve the credit. I can
>> just help to review & ack.
> 
> As it's a (latent) bug fix, I'll do it separately, so that it can also
> make it into 4.0 and 4.1. Independent of the above, I'll probably do
> the adjustment to both legacy and MSI paths, though, even if the latter 
> should turn out benign.

It is fine. I will have a look at it when the patch is ready.

Jimmy



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel