From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hu Tao <hutao@cn.fujitsu.com>
Subject: Re: [PATCH v11] kvm: notify host when the guest is panicked
Date: Tue, 20 Nov 2012 18:09:48 +0800
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Cc: Sasha Levin <levinsasha928@gmail.com>,
	Wen Congyang <wency@cn.fujitsu.com>,
	kvm list <kvm@vger.kernel.org>,
	qemu-devel <qemu-devel@nongnu.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Avi Kivity <avi@redhat.com>,
	"Daniel P. Berrange" <berrange@redhat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Gleb Natapov <gleb@redhat.com>,
	Blue Swirl <blauwirbel@gmail.com>,
	Eric Blake <eblake@redhat.com>,
	Andrew Jones <drjones@redhat.com>,
	Luiz Capitulino <lcapitulino@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20121113021908.GA8176@amt.cnet>
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Hi Marcelo,

On Tue, Nov 13, 2012 at 12:19:08AM -0200, Marcelo Tosatti wrote:
> On Fri, Nov 09, 2012 at 03:17:39PM -0500, Sasha Levin wrote:
> > On Mon, Nov 5, 2012 at 8:58 PM, Hu Tao <hutao@cn.fujitsu.com> wrote:
> > > But in the case of panic notification, more dependency means more
> > > chances of failure of panic notification. Say, if we use a virtio device
> > > to do panic notification, then we will fail if: virtio itself has
> > > problems, virtio for some reason can't be deployed(neither built-in or
> > > as a module), or guest doesn't support virtio, etc.
> > 
> > Add polling to your virtio device. If it didn't notify of a panic but
> > taking more than 20 sec to answer your poll request you can assume
> > it's dead.
> > 
> > Actually, just use virtio-serial and something in userspace on the guest.
> 
> They want the guest to stop, so a memory dump can be taken by management
> interface.
> 
> Hu Tao, lets assume port I/O is the preferred method for communication.

Okey.

> Now, the following comments have still not been addressed:
> 
> 1) Lifecycle of the stopped guest and interaction with other stopped
> states in QEMU.

Patch 3 already deals with run state transitions. But in case I'm
missing something, could you be more specific?

> 
> 2) Format of the interface for other architectures (you can choose
> a different KVM supported architecture and write an example).
> 
> 3) Clear/documented management interface for the feature.

It is documented in patch 0: Documentation/virtual/kvm/pv_event.txt.
Does it need to be improved?