From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3CCDC4727D for ; Thu, 24 Sep 2020 09:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CE142376F for ; Thu, 24 Sep 2020 09:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727369AbgIXJJA (ORCPT ); Thu, 24 Sep 2020 05:09:00 -0400 Received: from 8bytes.org ([81.169.241.247]:46258 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727349AbgIXJI7 (ORCPT ); Thu, 24 Sep 2020 05:08:59 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id C04143D1; Thu, 24 Sep 2020 11:08:58 +0200 (CEST) Date: Thu, 24 Sep 2020 11:08:57 +0200 From: Joerg Roedel To: Baoquan He Cc: ahuang12@lenovo.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Revert "iommu/amd: Treat per-device exclusion ranges as r/w unity-mapped regions" Message-ID: <20200924090857.GG27174@8bytes.org> References: <20200923022655.750-1-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200923022655.750-1-bhe@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 23, 2020 at 10:26:55AM +0800, Baoquan He wrote: > A regression failure of kdump kernel boot was reported on a HPE system. > Bisect points at commit 387caf0b759ac43 ("iommu/amd: Treat per-device > exclusion ranges as r/w unity-mapped regions") as criminal. Reverting it > fix the failure. > > With the commit, kdump kernel will always print below error message, then > naturally AMD iommu can't function normally during kdump kernel bootup. > > ~~~~~~~~~ > AMD-Vi: [Firmware Bug]: IVRS invalid checksum > > Why commit 387caf0b759ac43 causing it haven't been made clear. I think this should be debugged further, in future IOMMUs the exclusion range feature will not be available anymore (mmio-fields get re-used for SNP). So starting to use them again is not going to work. Regards, Joerg