From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752676AbbELF5X (ORCPT ); Tue, 12 May 2015 01:57:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60420 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752064AbbELF5U (ORCPT ); Tue, 12 May 2015 01:57:20 -0400 Date: Tue, 12 May 2015 13:57:07 +0800 From: Dave Young To: Joerg Roedel Cc: "Li, Zhen-Hua" , dwmw2@infradead.org, indou.takao@jp.fujitsu.com, bhe@redhat.com, vgoyal@redhat.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, kexec@lists.infradead.org, alex.williamson@redhat.com, ddutile@redhat.com, ishii.hironobu@jp.fujitsu.com, bhelgaas@google.com, doug.hatch@hp.com, jerry.hoemann@hp.com, tom.vaden@hp.com, li.zhang6@hp.com, lisa.mitchell@hp.com, billsumnerlinux@gmail.com, rwright@hp.com Subject: Re: [PATCH v9 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel Message-ID: <20150512055707.GB29874@localhost.localdomain> References: <1426743388-26908-1-git-send-email-zhen-hual@hp.com> <20150403084031.GF22579@dhcp-128-53.nay.redhat.com> <20150504110551.GD15736@8bytes.org> <20150507135600.GB4559@localhost.localdomain> <20150511101124.GG20611@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150511101124.GG20611@8bytes.org> User-Agent: Mutt/1.5.22.1-rc1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/11/15 at 12:11pm, Joerg Roedel wrote: > On Thu, May 07, 2015 at 09:56:00PM +0800, Dave Young wrote: > > Joreg, I can not find the last reply from you, so just reply here about > > my worries here. > > > > I said that the patchset will cause more problems, let me explain about > > it more here: > > > > Suppose page table was corrupted, ie. original mapping iova1 -> page 1 > > it was changed to iova1 -> page 2 accidently while crash happening, > > thus future dma will read/write page 2 instead page 1, right? > > When the page-table is corrupted then it is a left-over from the old > kernel. When the kdump kernel boots the situation can at least not get > worse. For the page tables it is also hard to detect wrong mappings (if > this would be possible the hardware could already do it), so any checks > we could do there are of limited use anyway. Joerg, since both of you guys do not think it is a problem I will object it any more though I still do not like reusing the old page tables. So let's leave it as a future issue. Thanks Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Ys3CH-00080j-Ei for kexec@lists.infradead.org; Tue, 12 May 2015 05:57:42 +0000 Date: Tue, 12 May 2015 13:57:07 +0800 From: Dave Young Subject: Re: [PATCH v9 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel Message-ID: <20150512055707.GB29874@localhost.localdomain> References: <1426743388-26908-1-git-send-email-zhen-hual@hp.com> <20150403084031.GF22579@dhcp-128-53.nay.redhat.com> <20150504110551.GD15736@8bytes.org> <20150507135600.GB4559@localhost.localdomain> <20150511101124.GG20611@8bytes.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20150511101124.GG20611@8bytes.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Joerg Roedel Cc: alex.williamson@redhat.com, indou.takao@jp.fujitsu.com, bhe@redhat.com, tom.vaden@hp.com, rwright@hp.com, linux-pci@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, jerry.hoemann@hp.com, iommu@lists.linux-foundation.org, "Li, Zhen-Hua" , ddutile@redhat.com, doug.hatch@hp.com, ishii.hironobu@jp.fujitsu.com, bhelgaas@google.com, billsumnerlinux@gmail.com, li.zhang6@hp.com, dwmw2@infradead.org, vgoyal@redhat.com On 05/11/15 at 12:11pm, Joerg Roedel wrote: > On Thu, May 07, 2015 at 09:56:00PM +0800, Dave Young wrote: > > Joreg, I can not find the last reply from you, so just reply here about > > my worries here. > > > > I said that the patchset will cause more problems, let me explain about > > it more here: > > > > Suppose page table was corrupted, ie. original mapping iova1 -> page 1 > > it was changed to iova1 -> page 2 accidently while crash happening, > > thus future dma will read/write page 2 instead page 1, right? > > When the page-table is corrupted then it is a left-over from the old > kernel. When the kdump kernel boots the situation can at least not get > worse. For the page tables it is also hard to detect wrong mappings (if > this would be possible the hardware could already do it), so any checks > we could do there are of limited use anyway. Joerg, since both of you guys do not think it is a problem I will object it any more though I still do not like reusing the old page tables. So let's leave it as a future issue. Thanks Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec