From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758003Ab0DACos (ORCPT ); Wed, 31 Mar 2010 22:44:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23692 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752539Ab0DACor (ORCPT ); Wed, 31 Mar 2010 22:44:47 -0400 Date: Wed, 31 Mar 2010 22:44:21 -0400 From: Vivek Goyal To: Chris Wright Cc: Neil Horman , iommu@lists.linux-foundation.org, joerg.roedel@amd.com, hbabu@us.ibm.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] amd iommu: force flush of iommu prior during shutdown Message-ID: <20100401024421.GA5877@redhat.com> References: <20100331152417.GB13406@hmsreliant.think-freely.org> <20100331212535.GR29241@sequoia.sous-sol.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100331212535.GR29241@sequoia.sous-sol.org> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 31, 2010 at 02:25:35PM -0700, Chris Wright wrote: > * Neil Horman (nhorman@tuxdriver.com) wrote: > > Flush iommu during shutdown > > > > When using an iommu, its possible, if a kdump kernel boot follows a primary > > kernel crash, that dma operations might still be in flight from the previous > > kernel during the kdump kernel boot. This can lead to memory corruption, > > crashes, and other erroneous behavior, specifically I've seen it manifest during > > a kdump boot as endless iommu error log entries of the form: > > AMD-Vi: Event logged [IO_PAGE_FAULT device=00:14.1 domain=0x000d > > address=0x000000000245a0c0 flags=0x0070] > > We've already fixed this problem once before, so some code shift must > have brought it back. Personally, I prefer to do this on the bringup > path than the teardown path. Besides keeping the teardown path as > simple as possible (goal is to get to kdump kernel asap), there's also > reason to competely flush on startup in genernal in case BIOS has done > anything unsavory. Can we flush domains (all the I/O TLBs assciated with each domain), during initialization? I think all the domain data built by previous kernel will be lost and new kernel will have no idea about. Thanks Vivek