From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from serv2.oss.ntt.co.jp ([222.151.198.100]) by casper.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1S7HDN-0002FU-EU for kexec@lists.infradead.org; Tue, 13 Mar 2012 02:11:55 +0000 Message-ID: <4F5EACE5.8080202@oss.ntt.co.jp> Date: Tue, 13 Mar 2012 11:11:49 +0900 From: =?UTF-8?B?RmVybmFuZG8gTHVpcyBWw6F6cXVleiBDYW8=?= MIME-Version: 1.0 Subject: Re: [PATCH 1/2] boot: ignore early NMIs References: <20120216215603.GH9751@redhat.com> <20120217195430.GO9751@redhat.com> <20120220151419.GU9751@redhat.com> <20120221135934.GF26998@redhat.com> <4F573E1C.2060909@oss.ntt.co.jp> <4F573E74.5040504@oss.ntt.co.jp> <4F58495B.5080308@oss.ntt.co.jp> <4F5A6D87.4050809@zytor.com> <4F5D8D0E.8060702@oss.ntt.co.jp> <4F5D8E63.60606@zytor.com> <4F5D943C.5020403@oss.ntt.co.jp> <4F5E431D.8010305@zytor.com> <4F5E56EB.1090807@zytor.com> <4F5E59AC.7090708@zytor.com> In-Reply-To: <4F5E59AC.7090708@zytor.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "H. Peter Anvin" Cc: Don Zickus , akpm@linux-foundation.org, linux-tip-commits@vger.kernel.org, Yinghai Lu , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, "Eric W. Biederman" , tglx@linutronix.de, torvalds@linux-foundation.org, mingo@elte.hu, vgoyal@redhat.com On 03/13/2012 05:16 AM, H. Peter Anvin wrote: > On 03/12/2012 01:04 PM, H. Peter Anvin wrote: >> On 03/12/2012 01:01 PM, Eric W. Biederman wrote: >>> The basic problem is which source do we block this at? How many >>> sources are their? And architecturally last I looked x86 no longer >>> has a NMI disable EFI and similar systems want to get away without >>> a CMOS legacy clock because designers so often get them wrong. >>> >> On all processors which have an LAPIC you can block all NMI sources at >> the LAPIC. I think it's safe to assume that if you don't have an LAPIC >> -- an ancient system by now -- you have port 70h. >> > One thing: *disabling* the LAPIC will allow external NMIs coming in on > LINT1 through, since the LAPIC in the disabled state tries to mimic the > no-LAPIC configuration. So I don't think you want to disable LAPIC as > much as disable the interrupt vectors within. Does this sound like a plan to get the ball rolling?: 1.- Merge Don's patch to disable the LAPIC in kdump reboot path (this fixes a real issue seen in the field, is a net win and certainly not a regression - indeed it makes the code simpler because the I/O APICs are left untouched). 2.- Merge my patch set to ignore early NMIs (this brings the behavior of the boot code in line with what we do in the rest of the kernel a we can avoid situations were a spurious NMI causes the kernel to halt). The early NMI handler is temporary and the final NMI handler installed shortly afterwards will take care of subsequent NMIs. 3.- Make sure that spurious NMIs (i.e. NMIs that for whatever reason could not be stopped at the source) received during the reboot path to the kdump kernel do not cause a triple fault or a system lockup. This is under testing. 4.- Identify all the NMI sources and keep them from reaching the CPU when it can be done in a race-free way. Can we get 1 and 2 merged while we work on further improvements (3 and 4)? Thanks, Fernando _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759007Ab2CMCLw (ORCPT ); Mon, 12 Mar 2012 22:11:52 -0400 Received: from serv2.oss.ntt.co.jp ([222.151.198.100]:43526 "EHLO serv2.oss.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755825Ab2CMCLv (ORCPT ); Mon, 12 Mar 2012 22:11:51 -0400 Message-ID: <4F5EACE5.8080202@oss.ntt.co.jp> Date: Tue, 13 Mar 2012 11:11:49 +0900 From: =?UTF-8?B?RmVybmFuZG8gTHVpcyBWw6F6cXVleiBDYW8=?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Eric W. Biederman" , Don Zickus , linux-tip-commits@vger.kernel.org, torvalds@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu, Yinghai Lu , akpm@linux-foundation.org, vgoyal@redhat.com Subject: Re: [PATCH 1/2] boot: ignore early NMIs References: <20120216215603.GH9751@redhat.com> <20120217195430.GO9751@redhat.com> <20120220151419.GU9751@redhat.com> <20120221135934.GF26998@redhat.com> <4F573E1C.2060909@oss.ntt.co.jp> <4F573E74.5040504@oss.ntt.co.jp> <4F58495B.5080308@oss.ntt.co.jp> <4F5A6D87.4050809@zytor.com> <4F5D8D0E.8060702@oss.ntt.co.jp> <4F5D8E63.60606@zytor.com> <4F5D943C.5020403@oss.ntt.co.jp> <4F5E431D.8010305@zytor.com> <4F5E56EB.1090807@zytor.com> <4F5E59AC.7090708@zytor.com> In-Reply-To: <4F5E59AC.7090708@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/13/2012 05:16 AM, H. Peter Anvin wrote: > On 03/12/2012 01:04 PM, H. Peter Anvin wrote: >> On 03/12/2012 01:01 PM, Eric W. Biederman wrote: >>> The basic problem is which source do we block this at? How many >>> sources are their? And architecturally last I looked x86 no longer >>> has a NMI disable EFI and similar systems want to get away without >>> a CMOS legacy clock because designers so often get them wrong. >>> >> On all processors which have an LAPIC you can block all NMI sources at >> the LAPIC. I think it's safe to assume that if you don't have an LAPIC >> -- an ancient system by now -- you have port 70h. >> > One thing: *disabling* the LAPIC will allow external NMIs coming in on > LINT1 through, since the LAPIC in the disabled state tries to mimic the > no-LAPIC configuration. So I don't think you want to disable LAPIC as > much as disable the interrupt vectors within. Does this sound like a plan to get the ball rolling?: 1.- Merge Don's patch to disable the LAPIC in kdump reboot path (this fixes a real issue seen in the field, is a net win and certainly not a regression - indeed it makes the code simpler because the I/O APICs are left untouched). 2.- Merge my patch set to ignore early NMIs (this brings the behavior of the boot code in line with what we do in the rest of the kernel a we can avoid situations were a spurious NMI causes the kernel to halt). The early NMI handler is temporary and the final NMI handler installed shortly afterwards will take care of subsequent NMIs. 3.- Make sure that spurious NMIs (i.e. NMIs that for whatever reason could not be stopped at the source) received during the reboot path to the kdump kernel do not cause a triple fault or a system lockup. This is under testing. 4.- Identify all the NMI sources and keep them from reaching the CPU when it can be done in a race-free way. Can we get 1 and 2 merged while we work on further improvements (3 and 4)? Thanks, Fernando