From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758218Ab0J1Hav (ORCPT ); Thu, 28 Oct 2010 03:30:51 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:64522 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758092Ab0J1Hau (ORCPT ); Thu, 28 Oct 2010 03:30:50 -0400 Message-ID: <4CC927B1.2020807@cn.fujitsu.com> Date: Thu, 28 Oct 2010 15:35:13 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100713 Thunderbird/3.0.6 MIME-Version: 1.0 To: Gleb Natapov CC: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH 5/8] KVM: don't touch vcpu stat after async pf is complete References: <4CC7EA7D.5020901@cn.fujitsu.com> <4CC7EB75.9030709@cn.fujitsu.com> <20101027104412.GO26191@redhat.com> In-Reply-To: <20101027104412.GO26191@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/27/2010 06:44 PM, Gleb Natapov wrote: > On Wed, Oct 27, 2010 at 05:05:57PM +0800, Xiao Guangrong wrote: >> Don't make a KVM_REQ_UNHALT request after async pf is completed since it >> can break guest's 'halt' instruction. >> > Why is it a problem? CPU may be unhalted by different events so OS > shouldn't depend on it. > We don't know how guest OS handles it after HLT instruction is completed, according to X86's spec, only NMI/INTR/RESET/INIT/SMI can break halt state, it violations the hardware behavior if we allow other event break this state. Your opinion? :-)