From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: [patch] KVM: T60 resume fix
Date: Mon, 05 Mar 2007 10:50:04 +0200
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To: Ingo Molnar <mingo@elte.hu>
Cc: Daniel Walker <dwalker@mvista.com>, Michal Piotrowski <michal.k.k.piotrowski@gmail.com>, linux-pm@lists.osdl.org, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Adrian Bunk <bunk@stusta.de>, Pavel Machek <pavel@ucw.cz>, Jens Axboe <jens.axboe@oracle.com>, "Michael S. Tsirkin" <mst@mellanox.co.il>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>
List-Id: linux-pm@vger.kernel.org

Ingo Molnar wrote:
> * Avi Kivity <avi@qumranet.com> wrote:
>
>   =

>>> my T60 laptop does not resume correctly due to KVM attempting to =

>>> send an IPI to a CPU that might be down (or not up yet). (Doing so =

>>> also triggers the send_IPI_mask_bitmask() warning in =

>>> arch/i386/kernel/smp.c, line 732.)
>>>
>>> with this fix applied my laptop does not hang during resume.
>>>
>>> [ KVM will have to disable/enable virtualization on the CPU itself =

>>>  that goes down / comes up, not via an IPI sent from the requesting
>>> CPU. ]
>>>       =

>
>   =

>> That is already CPU_ONLINE in my tree (and in the pull request sent to =

>> Linus a couple of days ago).
>>     =

>
> that solves the resume problem - but doesnt solve the CPU_DEAD issue of =

> sending an IPI to an already offline CPU. Might be a better idea to do =

> it in CPU_DOWN_PREPARE? (and then to also add a CPU_DOWN_FAILED branch?)
>
> 	=


Mainline now has DOWN_PREPARE and UP_CANCELED calling =

->hardware_disable(), and ONLINE calling ->hardware_enabled().  What =

tree are you looking at?

[but I do see the need for DOWN_FAILED now. Off to find a resumable =

machine...]


-- =

Do not meddle in the internals of kernels, for they are subtle and quick to=
 panic.