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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70032C433F5 for ; Wed, 20 Oct 2021 05:21:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4702460698 for ; Wed, 20 Oct 2021 05:21:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230020AbhJTFYG (ORCPT ); Wed, 20 Oct 2021 01:24:06 -0400 Received: from mga05.intel.com ([192.55.52.43]:3182 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229920AbhJTFYF (ORCPT ); Wed, 20 Oct 2021 01:24:05 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10142"; a="314896509" X-IronPort-AV: E=Sophos;i="5.87,165,1631602800"; d="scan'208";a="314896509" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2021 22:21:51 -0700 X-IronPort-AV: E=Sophos;i="5.87,165,1631602800"; d="scan'208";a="594517234" Received: from qsu-mobl.ccr.corp.intel.com (HELO [10.254.215.183]) ([10.254.215.183]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2021 22:21:46 -0700 Message-ID: <9e25f2c0-d9d3-475d-e973-63be1891f9a5@linux.intel.com> Date: Wed, 20 Oct 2021 13:21:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Cc: baolu.lu@linux.intel.com, Arnd Bergmann , Marc Zyngier , Hector Martin , linux-kernel@vger.kernel.org, Alexander Graf , Mohamed Mediouni , Will Deacon , Alyssa Rosenzweig Subject: Re: [PATCH v3 4/6] iommu: Move IOMMU pagesize check to attach_device Content-Language: en-US To: Sven Peter , iommu@lists.linux-foundation.org, Robin Murphy References: <20211019163737.46269-1-sven@svenpeter.dev> <20211019163737.46269-5-sven@svenpeter.dev> From: Lu Baolu In-Reply-To: <20211019163737.46269-5-sven@svenpeter.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/10/20 0:37, Sven Peter via iommu wrote: > The iova allocator is capable of handling any granularity which is a power > of two. Remove the much stronger condition that the granularity must be > smaller or equal to the CPU page size from a BUG_ON there. > Instead, check this condition during __iommu_attach_device and fail > gracefully. > > Signed-off-by: Sven Peter > --- > drivers/iommu/iommu.c | 35 ++++++++++++++++++++++++++++++++--- > drivers/iommu/iova.c | 7 ++++--- > include/linux/iommu.h | 5 +++++ > 3 files changed, 41 insertions(+), 6 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index dd7863e453a5..28896739964b 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -80,6 +80,8 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > unsigned type); > static int __iommu_attach_device(struct iommu_domain *domain, > struct device *dev); > +static void __iommu_detach_device(struct iommu_domain *domain, > + struct device *dev); > static int __iommu_attach_group(struct iommu_domain *domain, > struct iommu_group *group); > static void __iommu_detach_group(struct iommu_domain *domain, > @@ -1974,6 +1976,19 @@ void iommu_domain_free(struct iommu_domain *domain) > } > EXPORT_SYMBOL_GPL(iommu_domain_free); > > +static int iommu_check_page_size(struct iommu_domain *domain) > +{ > + if (!iommu_is_paging_domain(domain)) > + return 0; > + > + if (!(domain->pgsize_bitmap & (PAGE_SIZE | (PAGE_SIZE - 1)))) { > + pr_warn("IOMMU pages cannot exactly represent CPU pages.\n"); > + return -EFAULT; > + } > + > + return 0; > +} > + > static int __iommu_attach_device(struct iommu_domain *domain, > struct device *dev) > { > @@ -1983,9 +1998,23 @@ static int __iommu_attach_device(struct iommu_domain *domain, > return -ENODEV; > > ret = domain->ops->attach_dev(domain, dev); > - if (!ret) > - trace_attach_device_to_domain(dev); > - return ret; > + if (ret) > + return ret; > + > + /* > + * Check that CPU pages can be represented by the IOVA granularity. > + * This has to be done after ops->attach_dev since many IOMMU drivers > + * only limit domain->pgsize_bitmap after having attached the first > + * device. > + */ > + ret = iommu_check_page_size(domain); > + if (ret) { > + __iommu_detach_device(domain, dev); > + return ret; > + } It looks odd. __iommu_attach_device() attaches an I/O page table for a device. How does it relate to CPU pages? Why is it a failure case if CPU page size is not covered? Best regards, baolu