From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from terminus.zytor.com ([2001:1868:205::10] helo=mail.zytor.com) by casper.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1S6y95-00019q-GW for kexec@lists.infradead.org; Mon, 12 Mar 2012 05:50:13 +0000 Message-ID: <4F5D8E63.60606@zytor.com> Date: Sun, 11 Mar 2012 22:49:23 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH 1/2] boot: ignore early NMIs References: <20120216172735.GX9751@redhat.com> <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> In-Reply-To: <4F5D8D0E.8060702@oss.ntt.co.jp> 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: =?UTF-8?B?RmVybmFuZG8gTHVpcyBWw6F6cXVleiBDYW8=?= 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 T24gMDMvMTEvMjAxMiAxMDo0MyBQTSwgRmVybmFuZG8gTHVpcyBWw6F6cXVleiBDYW8gd3JvdGU6 Cgo+IAo+IFRvIHRhY2tsZSB0aGlzIGlzc3VlIHdlIGNhbiBlaXRoZXIgc3RvcCB0aGUgaGFyZGxv Y2t1cCBkZXRlY3Rvcgo+IG9yIGRpc2FibGUgdGhlIExBUElDICh0aGUgTk1JcyBuZWVkZWQgYnkg eDg2J3MgaGFyZGxvY2t1cCBkZXRlY3Rvcgo+IGFyZSBnZW5lcmF0ZWQgdXNpbmcgcGVyZm9ybWFu Y2UgY291bnRlcnMgaW4gdGhlIExBUElDKSwgbGVhdmluZwo+IHRoZSBJL08gQVBJQ3MgdW50b3Vj aGVkLiBUaGUgc2Vjb25kIGlzIHNpbXBsZXIgYW5kIEkgdGhpbmsgaXQKPiBpcyB0aGUgYXBwcm9h Y2ggRG9uIHRvb2sgdG8gZml4IHRoaXMgaXNzdWUgaW4gUkhFTCBrZXJuZWxzLgo+IAo+IFVuZm9y dHVuYXRlbHksIHRoaXMgaXMgbm90IGVub3VnaCwgd2UgYXJlIHN0aWxsIGV4cG9zZWQgdG8gZXh0 ZXJuYWwKPiBOTUlzIG5vdCByb3V0ZWQgdGhyb3VnaCB0aGUgTEFQSUMuIEluIG90aGVyIHdvcmRz LCB3ZSBoYXZlIHRvIG1ha2UKPiBzdXJlIHRoYXQgd2UgYWx3YXlzIGhhdmUgYW5kIElEVCB0aGF0 IGlzIGFibGUgdG8gaGFuZGxlIE5NSXMgd2l0aG91dAo+IHNlZW1pbmdseSByYW5kb20gcmVib290 cyBhbmQgbG9ja3Vwcy4gVG8gYWNoaWV2ZSB0aGlzIGdvYWwgd2UgbmVlZAo+IHRvIGZpeCBtYWNo aW5lX2tleGVjKCkgYW5kIHRoZSBlYXJseSBJRFQgaGFuZGxlcnMuIFRoZSBjdXJyZW50IHBhdGNo Cj4gc2V0IHRha2VzIGNhcmUgb2YgdGhlIGxhdHRlci4KPiAKClRoZSBvbmx5IHNvdXJjZSBvZiBO TUlzIG90aGVyIHRoYW4gdGhlIExBUElDIHNob3VsZCBiZSB0aGUgc3lzdGVtIGVycm9yCndoaWNo IGNhbiBiZSBkaXNhYmxlZCB0aHJvdWdoIHRoZSBSVEMgcG9ydCwgc28gSSB0aGluayB5b3VyIHNl Y29uZApwYXJhZ3JhcGggaGVyZSBpcyB3YXkgbW9yZSBtZWNoYW5pc20gdGhhbiB5b3UgbmVlZCBm b3IgdmVyeSBsaXR0bGUgZ2Fpbi4KCgktaHBhCgotLSAKSC4gUGV0ZXIgQW52aW4sIEludGVsIE9w ZW4gU291cmNlIFRlY2hub2xvZ3kgQ2VudGVyCkkgd29yayBmb3IgSW50ZWwuICBJIGRvbid0IHNw ZWFrIG9uIHRoZWlyIGJlaGFsZi4KCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fXwprZXhlYyBtYWlsaW5nIGxpc3QKa2V4ZWNAbGlzdHMuaW5mcmFkZWFkLm9y ZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2tleGVjCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752930Ab2CLFuV (ORCPT ); Mon, 12 Mar 2012 01:50:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:48154 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751573Ab2CLFuR (ORCPT ); Mon, 12 Mar 2012 01:50:17 -0400 Message-ID: <4F5D8E63.60606@zytor.com> Date: Sun, 11 Mar 2012 22:49:23 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: =?UTF-8?B?RmVybmFuZG8gTHVpcyBWw6F6cXVleiBDYW8=?= 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: <20120216172735.GX9751@redhat.com> <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> In-Reply-To: <4F5D8D0E.8060702@oss.ntt.co.jp> X-Enigmail-Version: 1.3.5 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 On 03/11/2012 10:43 PM, Fernando Luis Vázquez Cao wrote: > > To tackle this issue we can either stop the hardlockup detector > or disable the LAPIC (the NMIs needed by x86's hardlockup detector > are generated using performance counters in the LAPIC), leaving > the I/O APICs untouched. The second is simpler and I think it > is the approach Don took to fix this issue in RHEL kernels. > > Unfortunately, this is not enough, we are still exposed to external > NMIs not routed through the LAPIC. In other words, we have to make > sure that we always have and IDT that is able to handle NMIs without > seemingly random reboots and lockups. To achieve this goal we need > to fix machine_kexec() and the early IDT handlers. The current patch > set takes care of the latter. > The only source of NMIs other than the LAPIC should be the system error which can be disabled through the RTC port, so I think your second paragraph here is way more mechanism than you need for very little gain. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.