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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 F3269C83019 for ; Mon, 23 Nov 2020 13:04:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A46892075A for ; Mon, 23 Nov 2020 13:04:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZCepca15" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388178AbgKWNEI (ORCPT ); Mon, 23 Nov 2020 08:04:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:40724 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388337AbgKWNDn (ORCPT ); Mon, 23 Nov 2020 08:03:43 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A49CA2075A; Mon, 23 Nov 2020 13:03:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606136621; bh=SgFY9Gwsrv3cNr7rUy8goxKDpPOG69zeXOVMmE/645Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZCepca15RXI93b6UId4XfpVNUKZvC1BVdBowf9oVGXzYgQKXnu1ZEvpBxY6+URyr+ 9Mskf+4qf6955vyhKyya/dAiiOzJpNEeUbgfYUQuKxLS7tSOhiJkK0izBSvY/eTzus PbkA1Nkrn9dBkqI2hJalKLYUgbaxwJcu+urJZajc= Date: Mon, 23 Nov 2020 13:03:36 +0000 From: Will Deacon To: Lu Baolu Cc: Joerg Roedel , Ashok Raj , Christoph Hellwig , Sohil Mehta , Robin Murphy , Jacob Pan , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Shameerali Kolothum Thodi Subject: Re: [PATCH v9 1/4] iommu: Move def_domain type check for untrusted device into core Message-ID: <20201123130335.GD10233@willie-the-truck> References: <20201121135620.3496419-1-baolu.lu@linux.intel.com> <20201121135620.3496419-2-baolu.lu@linux.intel.com> <20201123120449.GB10233@willie-the-truck> <5f6f0d5e-0cfc-2274-b186-180f50b8b1df@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5f6f0d5e-0cfc-2274-b186-180f50b8b1df@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Baolu, On Mon, Nov 23, 2020 at 08:55:17PM +0800, Lu Baolu wrote: > On 2020/11/23 20:04, Will Deacon wrote: > > On Sat, Nov 21, 2020 at 09:56:17PM +0800, Lu Baolu wrote: > > > @@ -1645,13 +1655,10 @@ struct __group_domain_type { > > > static int probe_get_default_domain_type(struct device *dev, void *data) > > > { > > > - const struct iommu_ops *ops = dev->bus->iommu_ops; > > > struct __group_domain_type *gtype = data; > > > unsigned int type = 0; > > > - if (ops->def_domain_type) > > > - type = ops->def_domain_type(dev); > > > - > > > + type = iommu_get_mandatory_def_domain_type(dev); > > > > afaict, this code is only called from probe_alloc_default_domain(), which > > has: > > > > /* Ask for default domain requirements of all devices in the group */ > > __iommu_group_for_each_dev(group, >ype, > > probe_get_default_domain_type); > > > > if (!gtype.type) > > gtype.type = iommu_def_domain_type; > > > > so is there actually a need to introduce the new > > iommu_get_mandatory_def_domain_type() function, given that a type of 0 > > always ends up resolving to the default domain type? > > Another consumer of this helper is in the next patch: > > + dev_def_dom = iommu_get_mandatory_def_domain_type(dev); > + > + /* Check if user requested domain is supported by the device or not */ > + if (!type) { > + /* > + * If the user hasn't requested any specific type of domain and > + * if the device supports both the domains, then default to the > + * domain the device was booted with > + */ > + type = iommu_get_def_domain_type(dev); > + } else if (dev_def_dom && type != dev_def_dom) { > + dev_err_ratelimited(prev_dev, "Device cannot be in %s domain\n", > + iommu_domain_type_str(type)); > + ret = -EINVAL; > + goto out; > + } > > I also added the untrusted device check in > iommu_get_mandatory_def_domain_type(), so that we don't need to care > about this in multiple places. I see, but isn't this also setting the default domain type in the case that it gets back a type of 0? I think it would be nice to avoid having both iommu_get_mandatory_def_domain_type() and iommu_get_def_domain_type() of we can, as it's really not clear which one to use when and what is meant by "mandatory" imo. Will