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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 DA729C49361 for ; Fri, 18 Jun 2021 13:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A459C608FC for ; Fri, 18 Jun 2021 13:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232837AbhFRNOH (ORCPT ); Fri, 18 Jun 2021 09:14:07 -0400 Received: from mga18.intel.com ([134.134.136.126]:54049 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232858AbhFRNOG (ORCPT ); Fri, 18 Jun 2021 09:14:06 -0400 IronPort-SDR: 9wAIvuyQbJgvsh1NwUOfHxhSPyrwHvmTN+SZuWfzqblSPAeoez27oOuuzs7tI+LP9uqwYdacjx YdUz9lXdYj7w== X-IronPort-AV: E=McAfee;i="6200,9189,10018"; a="193863555" X-IronPort-AV: E=Sophos;i="5.83,283,1616482800"; d="scan'208";a="193863555" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2021 06:11:56 -0700 IronPort-SDR: fUXp1eNyFe8UHrCwz/mApMUTcrdnOKODGqLQOfQ62eLnCaWEHWd9I2KQ/oYkSldHOKvWhTQkSW 5d8xDSpzz37w== X-IronPort-AV: E=Sophos;i="5.83,283,1616482800"; d="scan'208";a="485684332" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.254.212.157]) ([10.254.212.157]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2021 06:11:52 -0700 Cc: baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linuxarm@huawei.com, thunder.leizhen@huawei.com, chenxiang66@hisilicon.com, linux-doc@vger.kernel.org Subject: Re: [PATCH v14 3/6] iommu: Enhance IOMMU default DMA mode build options To: John Garry , joro@8bytes.org, will@kernel.org, dwmw2@infradead.org, robin.murphy@arm.com, corbet@lwn.net References: <1624016058-189713-1-git-send-email-john.garry@huawei.com> <1624016058-189713-4-git-send-email-john.garry@huawei.com> From: Lu Baolu Message-ID: <4bd4b850-720e-bd02-c04d-01013be49456@linux.intel.com> Date: Fri, 18 Jun 2021 21:11:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <1624016058-189713-4-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/6/18 19:34, John Garry wrote: > From: Zhen Lei > > First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the > opportunity to set {lazy|strict} mode as default at build time. Then put > the two config options in an choice, as they are mutually exclusive. > > [jpg: Make choice between strict and lazy only (and not passthrough)] > Signed-off-by: Zhen Lei > Signed-off-by: John Garry > Reviewed-by: Robin Murphy > --- > .../admin-guide/kernel-parameters.txt | 3 +- > drivers/iommu/Kconfig | 40 +++++++++++++++++++ > drivers/iommu/iommu.c | 2 +- > 3 files changed, 43 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 673952379900..a1b7c8526bb5 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2046,9 +2046,10 @@ > throughput at the cost of reduced device isolation. > Will fall back to strict mode if not supported by > the relevant IOMMU driver. > - 1 - Strict mode (default). > + 1 - Strict mode. > DMA unmap operations invalidate IOMMU hardware TLBs > synchronously. > + unset - Use value of CONFIG_IOMMU_DEFAULT_{LAZY,STRICT}. > Note: on x86, the default behaviour depends on the > equivalent driver-specific parameters, but a strict > mode explicitly specified by either method takes > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index 1f111b399bca..0327a942fdb7 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -90,6 +90,46 @@ config IOMMU_DEFAULT_PASSTHROUGH > > If unsure, say N here. > > +choice > + prompt "IOMMU default DMA IOTLB invalidation mode" > + depends on IOMMU_DMA > + > + default IOMMU_DEFAULT_STRICT > + help > + This option allows an IOMMU DMA IOTLB invalidation mode to be > + chosen at build time, to override the default mode of each ARCH, > + removing the need to pass in kernel parameters through command line. > + It is still possible to provide common boot params to override this > + config. > + > + If unsure, keep the default. > + > +config IOMMU_DEFAULT_STRICT > + bool "strict" > + help > + For every IOMMU DMA unmap operation, the flush operation of IOTLB and > + the free operation of IOVA are guaranteed to be done in the unmap > + function. > + > +config IOMMU_DEFAULT_LAZY > + bool "lazy" > + help > + Support lazy mode, where for every IOMMU DMA unmap operation, the > + flush operation of IOTLB and the free operation of IOVA are deferred. > + They are only guaranteed to be done before the related IOVA will be > + reused. > + > + The isolation provided in this mode is not as secure as STRICT mode, > + such that a vulnerable time window may be created between the DMA > + unmap and the mappings cached in the IOMMU IOTLB or device TLB > + finally being invalidated, where the device could still access the > + memory which has already been unmapped by the device driver. > + However this mode may provide better performance in high throughput > + scenarios, and is still considerably more secure than passthrough > + mode or no IOMMU. > + > +endchoice > + > config OF_IOMMU > def_bool y > depends on OF && IOMMU_API > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index cf58949cc2f3..60b1ec42e73b 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -29,7 +29,7 @@ static struct kset *iommu_group_kset; > static DEFINE_IDA(iommu_group_ida); > > static unsigned int iommu_def_domain_type __read_mostly; > -static bool iommu_dma_strict __read_mostly = true; > +static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT); > static u32 iommu_cmd_line __read_mostly; > > struct iommu_group { > Reviewed-by: Lu Baolu Best regards, baolu