From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from g9t5009.houston.hp.com ([15.240.92.67]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YdxV1-0001xi-Uk for kexec@lists.infradead.org; Fri, 03 Apr 2015 09:02:48 +0000 Message-ID: <551E56F6.60503@hp.com> Date: Fri, 03 Apr 2015 17:01:42 +0800 From: "Li, ZhenHua" MIME-Version: 1.0 Subject: Re: [PATCH v9 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel References: <1426743388-26908-1-git-send-email-zhen-hual@hp.com> <20150403084031.GF22579@dhcp-128-53.nay.redhat.com> In-Reply-To: <20150403084031.GF22579@dhcp-128-53.nay.redhat.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" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dave Young 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, 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 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. Thanks Zhenhua On 04/03/2015 04:40 PM, Dave Young wrote: >> To fix this problem, we modifies the behaviors of the intel vt-d in the >> crashdump kernel: >> >> For DMA Remapping: >> 1. To accept the vt-d hardware in an active state, >> 2. Do not disable and re-enable the translation, keep it enabled. >> 3. Use the old root entry table, do not rewrite the RTA register. >> 4. Malloc and use new context entry table, copy data from the old ones that >> used by the old kernel. > > Have not read all the patches, but I have a question, not sure this has been > answered before. Old memory is not reliable, what if the old memory get corrupted > before panic? Is it safe to continue using it in 2nd kernel, I worry that it will > cause problems. > > Hope I'm wrong though. > > Thanks > Dave > > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec