From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752117AbbEFI0G (ORCPT ); Wed, 6 May 2015 04:26:06 -0400 Received: from 8bytes.org ([81.169.241.247]:59760 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972AbbEFI0A (ORCPT ); Wed, 6 May 2015 04:26:00 -0400 Date: Wed, 6 May 2015 10:25:59 +0200 From: Joerg Roedel To: Dave Young Cc: Baoquan He , "Li, ZhenHua" , dwmw2@infradead.org, indou.takao@jp.fujitsu.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 v10 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel Message-ID: <20150506082559.GC20611@8bytes.org> References: <552DFB56.1070600@hp.com> <20150415064803.GF19051@localhost.localdomain> <20150424080147.GC4458@dhcp-16-116.nay.redhat.com> <20150424082528.GA23912@dhcp-128-91.nay.redhat.com> <20150424083530.GD4458@dhcp-16-116.nay.redhat.com> <20150424084957.GC23912@dhcp-128-91.nay.redhat.com> <20150504162318.GH15736@8bytes.org> <20150505061423.GC31063@dhcp-128-4.nay.redhat.com> <20150505153157.GQ15736@8bytes.org> <20150506015135.GB14065@dhcp-128-4.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150506015135.GB14065@dhcp-128-4.nay.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 06, 2015 at 09:51:35AM +0800, Dave Young wrote: > DMA write will modify system ram, if the old data is corrupted it is possible > that DMA operation modify wrong ram regions because of wrong mapping. > Am I missing something and is it not possible? This might have happened already before the kdump kernel even boots. Also, if there is no IOMMU, this can happen as well. This (unlikely but possible) situation doesn't make things worse. Joerg From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v10 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel Date: Wed, 6 May 2015 10:25:59 +0200 Message-ID: <20150506082559.GC20611@8bytes.org> References: <552DFB56.1070600@hp.com> <20150415064803.GF19051@localhost.localdomain> <20150424080147.GC4458@dhcp-16-116.nay.redhat.com> <20150424082528.GA23912@dhcp-128-91.nay.redhat.com> <20150424083530.GD4458@dhcp-16-116.nay.redhat.com> <20150424084957.GC23912@dhcp-128-91.nay.redhat.com> <20150504162318.GH15736@8bytes.org> <20150505061423.GC31063@dhcp-128-4.nay.redhat.com> <20150505153157.GQ15736@8bytes.org> <20150506015135.GB14065@dhcp-128-4.nay.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150506015135.GB14065-0VdLhd/A9PlTxLCkMk2GaBcY2uh10dtjAL8bYrjMMd8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Dave Young Cc: Baoquan He , tom.vaden-VXdhtT5mjnY@public.gmane.org, rwright-VXdhtT5mjnY@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lisa.mitchell-VXdhtT5mjnY@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, "Li, ZhenHua" , doug.hatch-VXdhtT5mjnY@public.gmane.org, ishii.hironobu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, billsumnerlinux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, li.zhang6-VXdhtT5mjnY@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Wed, May 06, 2015 at 09:51:35AM +0800, Dave Young wrote: > DMA write will modify system ram, if the old data is corrupted it is possible > that DMA operation modify wrong ram regions because of wrong mapping. > Am I missing something and is it not possible? This might have happened already before the kdump kernel even boots. Also, if there is no IOMMU, this can happen as well. This (unlikely but possible) situation doesn't make things worse. Joerg