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 1YeZmo-0002np-Ep for kexec@lists.infradead.org; Sun, 05 Apr 2015 01:55:43 +0000 Date: Sun, 5 Apr 2015 09:54:53 +0800 From: Baoquan He Subject: Re: [PATCH v9 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel Message-ID: <20150405015453.GB1562@dhcp-17-102.nay.redhat.com> References: <1426743388-26908-1-git-send-email-zhen-hual@hp.com> <20150403084031.GF22579@dhcp-128-53.nay.redhat.com> <551E56F6.60503@hp.com> <20150403092111.GG22579@dhcp-128-53.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20150403092111.GG22579@dhcp-128-53.nay.redhat.com> 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: Dave Young Cc: alex.williamson@redhat.com, indou.takao@jp.fujitsu.com, tom.vaden@hp.com, rwright@hp.com, linux-pci@vger.kernel.org, joro@8bytes.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, jerry.hoemann@hp.com, iommu@lists.linux-foundation.org, "Li, ZhenHua" , 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 04/03/15 at 05:21pm, Dave Young wrote: > On 04/03/15 at 05:01pm, Li, ZhenHua wrote: > > Hi Dave, > > > > There may be some possibilities that the old iommu data is corrupted by > > some other modules. Currently we do not have a better solution for the > > dmar faults. > > > > But I think when this happens, we need to fix the module that corrupted > > the old iommu data. I once met a similar problem in normal kernel, the > > queue used by the qi_* functions was written again by another module. > > The fix was in that module, not in iommu module. > > It is too late, there will be no chance to save vmcore then. > > Also if it is possible to continue corrupt other area of oldmem because > of using old iommu tables then it will cause more problems. > > So I think the tables at least need some verifycation before being used. > Yes, it's a good thinking anout this and verification is also an interesting idea. kexec/kdump do a sha256 calculation on loaded kernel and then verify this again when panic happens in purgatory. This checks whether any code stomps into region reserved for kexec/kernel and corrupt the loaded kernel. If this is decided to do it should be an enhancement to current patchset but not a approach change. Since this patchset is going very close to point as maintainers expected maybe this can be merged firstly, then think about enhancement. After all without this patchset vt-d often raised error message, hung. By the way I tested this patchset it works very well on my HP z420 work station. Thanks Baoquan _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec