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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 EC6DCC432C0 for ; Tue, 19 Nov 2019 17:27:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0CEB222B6 for ; Tue, 19 Nov 2019 17:27:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728478AbfKSR14 (ORCPT ); Tue, 19 Nov 2019 12:27:56 -0500 Received: from mga14.intel.com ([192.55.52.115]:15490 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728060AbfKSR14 (ORCPT ); Tue, 19 Nov 2019 12:27:56 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2019 09:27:55 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,218,1571727600"; d="scan'208";a="289673313" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga001.jf.intel.com with ESMTP; 19 Nov 2019 09:27:55 -0800 Date: Tue, 19 Nov 2019 09:32:31 -0800 From: Jacob Pan To: Auger Eric Cc: iommu@lists.linux-foundation.org, LKML , Joerg Roedel , Lu Baolu , David Woodhouse , "Tian, Kevin" , Raj Ashok , Yi Liu , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH v2 02/10] iommu/vt-d: Fix CPU and IOMMU SVM feature matching checks Message-ID: <20191119093231.65fb3b3f@jacob-builder> In-Reply-To: <3634dee5-3f9f-4618-951e-8bb5e4988223@redhat.com> References: <1574106153-45867-1-git-send-email-jacob.jun.pan@linux.intel.com> <1574106153-45867-3-git-send-email-jacob.jun.pan@linux.intel.com> <26d1e79b-3a16-0a8f-895e-e2c41c8d3b28@redhat.com> <20191118134719.6835981b@jacob-builder> <3634dee5-3f9f-4618-951e-8bb5e4988223@redhat.com> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 19 Nov 2019 09:02:26 +0100 Auger Eric wrote: > Hi Jacob, > > On 11/18/19 10:47 PM, Jacob Pan wrote: > > On Mon, 18 Nov 2019 21:33:34 +0100 > > Auger Eric wrote: > > > >> Hi Jacob, > >> > >> On 11/18/19 8:42 PM, Jacob Pan wrote: > >>> The current code checks CPU and IOMMU feature set for SVM support > >>> but the result is never stored nor used. Therefore, SVM can still > >>> be used even when these checks failed. > >> "SVM can still be used even when these checks failed". What were > >> the consequences if it happened? Does it fix this cleanly now. > >>> > > The consequence is DMA cannot reach above 48-bit virtual address > > range when CPU does 5-level and IOMMU can only do 4-level. With is > > fix, svm_bind_mm will fail in the first place to prevent SVM use by > > DMA. > OK thank you for the clarification. Maybe this latter can be added in > the commit message > > Yes, will do. > [...] > >> nit: is it really an error or just a warning? > > I think it is an error in that there is an illegal configuration. > > It is mostly for vIOMMU, we expect native HW should have these > > features matched. > > OK > > Thanks > > Eric > > > [...] > >> Besides, > >> Reviewed-by: Eric Auger > >> > >> Thanks > >> > >> Eric > >> > > > > [Jacob Pan] > > > [Jacob Pan]