From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from [222.73.24.84] (helo=song.cn.fujitsu.com) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TYZ4D-0005xJ-Bf for kexec@lists.infradead.org; Wed, 14 Nov 2012 09:15:30 +0000 Message-ID: <50A360C7.2070904@cn.fujitsu.com> Date: Wed, 14 Nov 2012 17:13:43 +0800 From: zhangyanfei MIME-Version: 1.0 Subject: Re: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when loading kvm_intel module References: <50909B55.2070901@cn.fujitsu.com> <50909C35.9080702@cn.fujitsu.com> <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> <50920EB8.3020400@cn.fujitsu.com> <20121113212203.GA26386@amt.cnet> In-Reply-To: <20121113212203.GA26386@amt.cnet> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Marcelo Tosatti Cc: "kvm@vger.kernel.org" , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "Hatayama, Daisuke" , Avi Kivity 5LqOIDIwMTLlubQxMeaciDE05pelIDA1OjIyLCBNYXJjZWxvIFRvc2F0dGkg5YaZ6YGTOgo+IE9u IFRodSwgTm92IDAxLCAyMDEyIGF0IDAxOjU1OjA0UE0gKzA4MDAsIHpoYW5neWFuZmVpIHdyb3Rl Ogo+PiDkuo4gMjAxMuW5tDEw5pyIMzHml6UgMTc6MDEsIEhhdGF5YW1hLCBEYWlzdWtlIOWGmemB kzoKPj4+Cj4+Pgo+Pj4+IC0tLS0tT3JpZ2luYWwgTWVzc2FnZS0tLS0tCj4+Pj4gRnJvbToga2V4 ZWMtYm91bmNlc0BsaXN0cy5pbmZyYWRlYWQub3JnCj4+Pj4gW21haWx0bzprZXhlYy1ib3VuY2Vz QGxpc3RzLmluZnJhZGVhZC5vcmddIE9uIEJlaGFsZiBPZiB6aGFuZ3lhbmZlaQo+Pj4+IFNlbnQ6 IFdlZG5lc2RheSwgT2N0b2JlciAzMSwgMjAxMiAxMjozNCBQTQo+Pj4+IFRvOiB4ODZAa2VybmVs Lm9yZzsga2V4ZWNAbGlzdHMuaW5mcmFkZWFkLm9yZzsgQXZpIEtpdml0eTsgTWFyY2Vsbwo+Pj4+ IFRvc2F0dGkKPj4+PiBDYzogbGludXgta2VybmVsQHZnZXIua2VybmVsLm9yZzsga3ZtQHZnZXIu a2VybmVsLm9yZwo+Pj4+IFN1YmplY3Q6IFtQQVRDSCB2MyAyLzJdIEtWTTogbWFrZSBjcmFzaF9j 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when loading kvm_intel module Date: Wed, 14 Nov 2012 17:13:43 +0800 Message-ID: <50A360C7.2070904@cn.fujitsu.com> References: <50909B55.2070901@cn.fujitsu.com> <50909C35.9080702@cn.fujitsu.com> <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> <50920EB8.3020400@cn.fujitsu.com> <20121113212203.GA26386@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Cc: "kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "Hatayama, Daisuke" , Avi Kivity To: Marcelo Tosatti Return-path: In-Reply-To: <20121113212203.GA26386-I4X2Mt4zSy4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kexec-bounces-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: kvm.vger.kernel.org 5LqOIDIwMTLlubQxMeaciDE05pelIDA1OjIyLCBNYXJjZWxvIFRvc2F0dGkg5YaZ6YGTOgo+IE9u IFRodSwgTm92IDAxLCAyMDEyIGF0IDAxOjU1OjA0UE0gKzA4MDAsIHpoYW5neWFuZmVpIHdyb3Rl Ogo+PiDkuo4gMjAxMuW5tDEw5pyIMzHml6UgMTc6MDEsIEhhdGF5YW1hLCBEYWlzdWtlIOWGmemB kzoKPj4+Cj4+Pgo+Pj4+IC0tLS0tT3JpZ2luYWwgTWVzc2FnZS0tLS0tCj4+Pj4gRnJvbToga2V4 ZWMtYm91bmNlc0BsaXN0cy5pbmZyYWRlYWQub3JnCj4+Pj4gW21haWx0bzprZXhlYy1ib3VuY2Vz QGxpc3RzLmluZnJhZGVhZC5vcmddIE9uIEJlaGFsZiBPZiB6aGFuZ3lhbmZlaQo+Pj4+IFNlbnQ6 IFdlZG5lc2RheSwgT2N0b2JlciAzMSwgMjAxMiAxMjozNCBQTQo+Pj4+IFRvOiB4ODZAa2VybmVs Lm9yZzsga2V4ZWNAbGlzdHMuaW5mcmFkZWFkLm9yZzsgQXZpIEtpdml0eTsgTWFyY2Vsbwo+Pj4+ IFRvc2F0dGkKPj4+PiBDYzogbGludXgta2VybmVsQHZnZXIua2VybmVsLm9yZzsga3ZtQHZnZXIu a2VybmVsLm9yZwo+Pj4+IFN1YmplY3Q6IFtQQVRDSCB2MyAyLzJdIEtWTTogbWFrZSBjcmFzaF9j bGVhcl9sb2FkZWRfdm1jc3MgdmFsaWQgd2hlbgo+Pj4+IGxvYWRpbmcga3ZtX2ludGVsIG1vZHVs 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cn.fujitsu.com ([222.73.24.84]:63760 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S932726Ab2KNJP1 convert rfc822-to-8bit (ORCPT ); Wed, 14 Nov 2012 04:15:27 -0500 X-IronPort-AV: E=Sophos;i="4.83,249,1352044800"; d="scan'208";a="6195591" Message-ID: <50A360C7.2070904@cn.fujitsu.com> Date: Wed, 14 Nov 2012 17:13:43 +0800 From: zhangyanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.8) Gecko/20121012 Thunderbird/10.0.8 MIME-Version: 1.0 To: Marcelo Tosatti CC: "Hatayama, Daisuke" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "x86@kernel.org" , "kexec@lists.infradead.org" , Avi Kivity Subject: Re: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when loading kvm_intel module References: <50909B55.2070901@cn.fujitsu.com> <50909C35.9080702@cn.fujitsu.com> <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> <50920EB8.3020400@cn.fujitsu.com> <20121113212203.GA26386@amt.cnet> In-Reply-To: <20121113212203.GA26386@amt.cnet> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/14 17:15:18, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/14 17:15:18 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2012年11月14日 05:22, Marcelo Tosatti 写道: > On Thu, Nov 01, 2012 at 01:55:04PM +0800, zhangyanfei wrote: >> 于 2012年10月31日 17:01, Hatayama, Daisuke 写道: >>> >>> >>>> -----Original Message----- >>>> From: kexec-bounces@lists.infradead.org >>>> [mailto:kexec-bounces@lists.infradead.org] On Behalf Of zhangyanfei >>>> Sent: Wednesday, October 31, 2012 12:34 PM >>>> To: x86@kernel.org; kexec@lists.infradead.org; Avi Kivity; Marcelo >>>> Tosatti >>>> Cc: linux-kernel@vger.kernel.org; kvm@vger.kernel.org >>>> Subject: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when >>>> loading kvm_intel module >>>> >>>> Signed-off-by: Zhang Yanfei >>> >>> [...] >>> >>>> @@ -7230,6 +7231,10 @@ static int __init vmx_init(void) >>>> if (r) >>>> goto out3; >>>> >>>> +#ifdef CONFIG_KEXEC >>>> + crash_clear_loaded_vmcss = vmclear_local_loaded_vmcss; >>>> +#endif >>>> + >>> >>> Assignment here cannot cover the case where NMI is initiated after VMX is on in kvm_init and before vmclear_local_loaded_vmcss is assigned, though rare but can happen. >>> >> >> By saying "VMX is on in kvm init", you mean kvm_init enables the VMX feature in the logical processor? >> No, only there is a vcpu to be created, kvm will enable the VMX feature. >> >> I think there is no difference with this assignment before or after kvm_init because the vmcs linked >> list must be empty before vmx_init is finished. > > The list is not initialized before hardware_enable(), though. Should > move the assignment after that. > > Also, it is possible that the loaded_vmcss_on_cpu list is being modified > _while_ crash executes say via NMI, correct? If that is the case, better > flag that the list is under manipulation so the vmclear can be skipped. > Thanks for your comments. In the new patchset, I didn't move the crash_clear_loaded_vmcss assignment. I added a new percpu variable vmclear_skipped to indicate everything: 1. Before the loaded_vmcss_on_cpu list is initialized, vmclear_skipped is 1 and this means if the machine crashes and doing kdump, crash_clear_loaded_vmcss still will not be called. 2. If the loaded_vmcss_on_cpu list is under manipulation, vmclear_skipped is set to 1 and after the manipulation is finished, the variable is set to 0. 3. After all loaded vmcss are vmcleared, vmclear_skipped is set to 1. So we needn't repeat to vmclear loaded vmcss in kdump path. Please refer to the new version of the patchset I sent. If you have any suggestions, that'll be helpful. Thanks Zhang