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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 A92B7C43387 for ; Fri, 11 Jan 2019 11:16:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77C1B20874 for ; Fri, 11 Jan 2019 11:16:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730046AbfAKLQr (ORCPT ); Fri, 11 Jan 2019 06:16:47 -0500 Received: from 8bytes.org ([81.169.241.247]:56854 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725801AbfAKLQq (ORCPT ); Fri, 11 Jan 2019 06:16:46 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 8D7CD434; Fri, 11 Jan 2019 12:16:45 +0100 (CET) Date: Fri, 11 Jan 2019 12:16:44 +0100 From: Joerg Roedel To: Lu Baolu Cc: David Woodhouse , Alex Williamson , Kirti Wankhede , ashok.raj@intel.com, sanjay.k.kumar@intel.com, jacob.jun.pan@intel.com, kevin.tian@intel.com, Jean-Philippe Brucker , yi.l.liu@intel.com, yi.y.sun@intel.com, peterx@redhat.com, tiwei.bie@intel.com, Zeng@8bytes.org, Xin , iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jacob Pan Subject: Re: [PATCH v5 2/8] iommu/vt-d: Add per-device IOMMU feature ops entries Message-ID: <20190111111644.epawu474jdjv4a33@8bytes.org> References: <20190110030027.31447-1-baolu.lu@linux.intel.com> <20190110030027.31447-3-baolu.lu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190110030027.31447-3-baolu.lu@linux.intel.com> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, this looks a bit confusing to me because I can see no checking whether the device actually supports scalable mode. More below: On Thu, Jan 10, 2019 at 11:00:21AM +0800, Lu Baolu wrote: > +static int intel_iommu_enable_auxd(struct device *dev) > +{ > + struct device_domain_info *info; > + struct dmar_domain *domain; > + unsigned long flags; > + > + if (!scalable_mode_support()) > + return -ENODEV; > + > + domain = get_valid_domain_for_dev(dev); > + if (!domain) > + return -ENODEV; > + > + spin_lock_irqsave(&device_domain_lock, flags); > + info = dev->archdata.iommu; > + info->auxd_enabled = 1; > + spin_unlock_irqrestore(&device_domain_lock, flags); > + > + return 0; > +} This code sets a flag to mark scalable mode enabled. Doesn't the device need some handling too, like enabling the PASID capability and all? > + > +static bool > +intel_iommu_dev_has_feat(struct device *dev, enum iommu_dev_features feat) > +{ > + struct device_domain_info *info = dev->archdata.iommu; > + > + if (feat == IOMMU_DEV_FEAT_AUX) > + return scalable_mode_support() && info && info->auxd_enabled; > + > + return false; > +} Why is this checking the auxd_enabled flag? The function should just return whether the device _supports_ scalable mode, not whether it is enabled. Regards, Joerg