From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932137Ab3CDPbi (ORCPT <rfc822;w@1wt.eu>);
	Mon, 4 Mar 2013 10:31:38 -0500
Received: from mx1.redhat.com ([209.132.183.28]:65095 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1758033Ab3CDPbf (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 4 Mar 2013 10:31:35 -0500
Date: Sun, 3 Mar 2013 19:29:53 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Hu Tao <hutao@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>,
        "Daniel P. Berrange" <berrange@redhat.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Jan Kiszka <jan.kiszka@siemens.com>, Blue Swirl <blauwirbel@gmail.com>,
        Eric Blake <eblake@redhat.com>, Andrew Jones <drjones@redhat.com>,
        Sasha Levin <levinsasha928@gmail.com>,
        Luiz Capitulino <lcapitulino@redhat.com>,
        Wen Congyang <wency@cn.fujitsu.com>
Subject: Re: [PATCH v12 rebased] kvm: notify host when the guest is panicked
Message-ID: <20130303222953.GB5922@amt.cnet>
References: <cover.1358920534.git.hutao@cn.fujitsu.com>
 <1358925575-4505-1-git-send-email-hutao@cn.fujitsu.com>
 <20130208013947.GA3364@amt.cnet>
 <20130228085425.GA16362@localhost.localdomain>
 <20130302000312.GA25309@amt.cnet>
 <20130303130022.GF23616@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20130303130022.GF23616@redhat.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Sun, Mar 03, 2013 at 03:00:22PM +0200, Gleb Natapov wrote:
> On Fri, Mar 01, 2013 at 09:03:12PM -0300, Marcelo Tosatti wrote:
> > On Thu, Feb 28, 2013 at 04:54:25PM +0800, Hu Tao wrote:
> > > > > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
> > > > > index 06fdbd9..c15ef33 100644
> > > > > --- a/arch/x86/include/uapi/asm/kvm_para.h
> > > > > +++ b/arch/x86/include/uapi/asm/kvm_para.h
> > > > > @@ -96,5 +96,7 @@ struct kvm_vcpu_pv_apf_data {
> > > > >  #define KVM_PV_EOI_ENABLED KVM_PV_EOI_MASK
> > > > >  #define KVM_PV_EOI_DISABLED 0x0
> > > > >  
> > > > > +#define KVM_PV_EVENT_PORT	(0x505UL)
> > > > > +
> > > > 
> > > > No need for the ioport to be hard coded. What are the options to
> > > > communicate an address to the guest? An MSR, via ACPI?
> > > 
> > > I'm not quite understanding here. By 'address', you mean an ioport?
> > > how to communicate an address? (I have little knowledge about ACPI)
> > 
> > Yes, the ioport. The address of the ioport should not be fixed (for
> > example future emulated board could use that fixed ioport address,
> > 0x505UL).
> > 
> > One option is to pass the address via an MSR. Yes, that is probably the
> > best option because there is no dependency on ACPI.
> > 
> Why dependency on ACPI is problematic? ACPI is the standard way on x86
> to enumerate platform devices. Passing it through MSR makes this panic
> device CPU interface which it is not. And since relying on #GP to detect
> valid MSRs is not good interface we will have to guard it by cpuid bit.
> 
> --
> 			Gleb.

KVM guest <-> KVM host interface is not dependent on ACPI, so far. Say,
its possible to use a Linux guest without ACPI and have KVM paravirt 
fully functional.