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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C1759C636CA for ; Wed, 21 Jul 2021 18:21:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5AEA61249 for ; Wed, 21 Jul 2021 18:21:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238941AbhGURlR (ORCPT ); Wed, 21 Jul 2021 13:41:17 -0400 Received: from foss.arm.com ([217.140.110.172]:33488 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238550AbhGURko (ORCPT ); Wed, 21 Jul 2021 13:40:44 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 26BD712FC; Wed, 21 Jul 2021 11:21:20 -0700 (PDT) Received: from 010265703453.arm.com (unknown [10.57.36.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A81CB3F694; Wed, 21 Jul 2021 11:21:18 -0700 (PDT) From: Robin Murphy To: joro@8bytes.org, will@kernel.org Cc: iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, suravee.suthikulpanit@amd.com, baolu.lu@linux.intel.com, john.garry@huawei.com, dianders@chromium.org Subject: [PATCH 20/23] iommu: Allow choosing DMA strictness at build time Date: Wed, 21 Jul 2021 19:20:31 +0100 Message-Id: <002cd8280cc4935e294d79bef838fbfb633bb3ed.1626888445.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To parallel the sysfs behaviour, extend the build-time configuration for default domains to include the new type as well. Signed-off-by: Robin Murphy --- This effectively replaces patch #3 of John's "iommu: Enhance IOMMU default DMA mode build options" series. --- drivers/iommu/Kconfig | 48 +++++++++++++++++++++++++++++++++++-------- drivers/iommu/iommu.c | 2 +- 2 files changed, 41 insertions(+), 9 deletions(-) diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 07b7c25cbed8..e3f7990046ae 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -79,16 +79,48 @@ config IOMMU_DEBUGFS debug/iommu directory, and then populate a subdirectory with entries as required. -config IOMMU_DEFAULT_PASSTHROUGH - bool "IOMMU passthrough by default" +choice + prompt "Default IOMMU domain type" depends on IOMMU_API - help - Enable passthrough by default, removing the need to pass in - iommu.passthrough=on or iommu=pt through command line. If this - is enabled, you can still disable with iommu.passthrough=off - or iommu=nopt depending on the architecture. + default IOMMU_DEFAULT_DMA_LAZY if INTEL_IOMMU || AMD_IOMMU + default IOMMU_DEFAULT_DMA_STRICT - If unsure, say N here. +config IOMMU_DEFAULT_DMA_STRICT + bool "Translated - Strict" + help + Trusted devices use translation to restrict their access to only + DMA-mapped pages, with strict TLB invalidation on unmap. Equivalent + to passing "iommu.passthrough=0 iommu.strict=1" on the command line. + + Untrusted devices always use this mode, with an additional layer of + bounce-buffering such that they cannot gain access to any unrelated + data within a mapped page. + +config IOMMU_DEFAULT_DMA_LAZY + bool "Translated - Lazy" + help + Trusted devices use translation to restrict their access to only + DMA-mapped pages, but with "lazy" batched TLB invalidation. This + mode allows higher performance with some IOMMUs due to reduced TLB + flushing, but at the cost of reduced isolation since devices may be + able to access memory for some time after it has been unmapped. + Equivalent to passing "iommu.passthrough=0 iommu.strict=0" on the + command line. + + If this mode is not supported by the IOMMU driver, the effective + runtime default will fall back to IOMMU_DEFAULT_DMA_STRICT. + +config IOMMU_DEFAULT_PASSTHROUGH + bool "Passthrough" + help + Trusted devices are identity-mapped, giving them unrestricted access + to memory with minimal performance overhead. Equivalent to passing + "iommu.passthrough=1" (historically "iommu=pt") on the command line. + + If this mode is not supported by the IOMMU driver, the effective + runtime default will fall back to IOMMU_DEFAULT_DMA_STRICT. + +endchoice config OF_IOMMU def_bool y diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index d3b562a33ac4..4fad6d427d9d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -30,7 +30,7 @@ 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_DMA_STRICT); static u32 iommu_cmd_line __read_mostly; struct iommu_group { -- 2.25.1