From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752548AbbDUBke (ORCPT ); Mon, 20 Apr 2015 21:40:34 -0400 Received: from g2t2354.austin.hp.com ([15.217.128.53]:33902 "EHLO g2t2354.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751276AbbDUBkd (ORCPT ); Mon, 20 Apr 2015 21:40:33 -0400 Message-ID: <5535AA57.6010404@hp.com> Date: Tue, 21 Apr 2015 09:39:35 +0800 From: "Li, ZhenHua" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Dave Young CC: dwmw2@infradead.org, indou.takao@jp.fujitsu.com, bhe@redhat.com, joro@8bytes.org, 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, "Li, ZhenHua" Subject: Re: [PATCH v10 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel References: <1428655333-19504-1-git-send-email-zhen-hual@hp.com> <20150415005731.GC19051@localhost.localdomain> <552DFB56.1070600@hp.com> <20150415064803.GF19051@localhost.localdomain> In-Reply-To: <20150415064803.GF19051@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dave, I found the old mail: http://lkml.iu.edu/hypermail/linux/kernel/1410.2/03584.html Please check this and you will find the discussion. Regards Zhenhua On 04/15/2015 02:48 PM, Dave Young wrote: > On 04/15/15 at 01:47pm, Li, ZhenHua wrote: >> On 04/15/2015 08:57 AM, Dave Young wrote: >>> Again, I think it is bad to use old page table, below issues need consider: >>> 1) make sure old page table are reliable across crash >>> 2) do not allow writing oldmem after crash >>> >>> Please correct me if I'm wrong, or if above is not doable I think I will vote for >>> resetting pci bus. >>> >>> Thanks >>> Dave >>> >> Hi Dave, >> >> When updating the context tables, we have to write their address to root >> tables, this will cause writing to old mem. >> >> Resetting the pci bus has been discussed, please check this: >> http://lists.infradead.org/pipermail/kexec/2014-October/012752.html >> https://lkml.org/lkml/2014/10/21/890 > > I know one reason to use old pgtable is this looks better because it fixes the > real problem, but it is not a good way if it introduce more problems because of > it have to use oldmem. I will be glad if this is not a problem but I have not > been convinced. > > OTOH, there's many types of iommu, intel, amd, a lot of other types. They need > their own fixes, so it looks not that elegant. > > For pci reset, it is not perfect, but it has another advantage, the patch is > simpler. The problem I see from the old discusssion is, reset bus in 2nd kernel > is acceptable but it does not fix things on sparc platform. AFAIK current reported > problems are intel and amd iommu, at least pci reset stuff does not make it worse. > > Thanks > Dave > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from g2t2354.austin.hp.com ([15.217.128.53]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YkNBH-0003Tl-Qs for kexec@lists.infradead.org; Tue, 21 Apr 2015 01:40:56 +0000 Message-ID: <5535AA57.6010404@hp.com> Date: Tue, 21 Apr 2015 09:39:35 +0800 From: "Li, ZhenHua" MIME-Version: 1.0 Subject: Re: [PATCH v10 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel References: <1428655333-19504-1-git-send-email-zhen-hual@hp.com> <20150415005731.GC19051@localhost.localdomain> <552DFB56.1070600@hp.com> <20150415064803.GF19051@localhost.localdomain> In-Reply-To: <20150415064803.GF19051@localhost.localdomain> 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, I found the old mail: http://lkml.iu.edu/hypermail/linux/kernel/1410.2/03584.html Please check this and you will find the discussion. Regards Zhenhua On 04/15/2015 02:48 PM, Dave Young wrote: > On 04/15/15 at 01:47pm, Li, ZhenHua wrote: >> On 04/15/2015 08:57 AM, Dave Young wrote: >>> Again, I think it is bad to use old page table, below issues need consider: >>> 1) make sure old page table are reliable across crash >>> 2) do not allow writing oldmem after crash >>> >>> Please correct me if I'm wrong, or if above is not doable I think I will vote for >>> resetting pci bus. >>> >>> Thanks >>> Dave >>> >> Hi Dave, >> >> When updating the context tables, we have to write their address to root >> tables, this will cause writing to old mem. >> >> Resetting the pci bus has been discussed, please check this: >> http://lists.infradead.org/pipermail/kexec/2014-October/012752.html >> https://lkml.org/lkml/2014/10/21/890 > > I know one reason to use old pgtable is this looks better because it fixes the > real problem, but it is not a good way if it introduce more problems because of > it have to use oldmem. I will be glad if this is not a problem but I have not > been convinced. > > OTOH, there's many types of iommu, intel, amd, a lot of other types. They need > their own fixes, so it looks not that elegant. > > For pci reset, it is not perfect, but it has another advantage, the patch is > simpler. The problem I see from the old discusssion is, reset bus in 2nd kernel > is acceptable but it does not fix things on sparc platform. AFAIK current reported > problems are intel and amd iommu, at least pci reset stuff does not make it worse. > > Thanks > Dave > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec