From patchwork Wed Jul 21 18:20:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 12391919 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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 438F1C12002 for ; Wed, 21 Jul 2021 18:35:56 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 109F16121E for ; Wed, 21 Jul 2021 18:35:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 109F16121E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SusvaB42oAo4C58Pou5uZKkgSRFH5fxHlFLD88UiXKU=; b=2PAD8k2y3SVmcm N2AcVRPKa0sts6pdXU3oTUnyN8PHCRLy//2YJkfaShxb+IL/XrgS/RfTVneAd1KNTAfZGfCxX3mbk dse3cEf1E86LZCLL6dVIxT1XkmA7KES2Khh+kki8ddUsGk4fT2WRTCneqfwQ/3b7yMBz3nEtnEaNq wFTNNaJibn1hXr0y2fc5TLHruCIbBhXcKn00gPvL8g5K1f97dAjduOqV0OMFozMjVXcUItDU2b/Jg 5IRdk0yUk0z4Bzbzd+3FrHfhyjvwcQJAJvdv0ZoEMTCHi3+qm9Zyv27YSqSBKS1Qn4ZbJpFPceb+N Wdfl5FJk5+NEsn0zA4dg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m6H2n-00GvTP-Fa; Wed, 21 Jul 2021 18:34:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m6GqS-00GpZ0-0S for linux-arm-kernel@lists.infradead.org; Wed, 21 Jul 2021 18:21:25 +0000 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 8F9FE13A1; Wed, 21 Jul 2021 11:21:23 -0700 (PDT) Received: from 010265703453.arm.com (unknown [10.57.36.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 1ED343F694; Wed, 21 Jul 2021 11:21:21 -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 22/23] iommu: Allow enabling non-strict mode dynamically Date: Wed, 21 Jul 2021 19:20:33 +0100 Message-Id: <5b3933e8c5c57dae52d398e4dcf3fdfec9779539.1626888445.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210721_112124_140564_4A6476E3 X-CRM114-Status: GOOD ( 19.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Allocating and enabling a flush queue is in fact something we can reasonably do while a DMA domain is active, without having to rebuild it from scratch. Thus we can allow a strict -> non-strict transition from sysfs without requiring to unbind the device's driver, which is of particular interest to users who want to make selective relaxations to critical devices like the one serving their root filesystem. Disabling and draining a queue also seems technically possible to achieve without rebuilding the whole domain, but would certainly be more involved. Furthermore there's not such a clear use-case for tightening up security *after* the device may already have done whatever it is that you don't trust it not to do, so we only consider the relaxation case. Signed-off-by: Robin Murphy --- drivers/iommu/iommu.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 4fad6d427d9d..43a2041d9629 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3130,6 +3130,13 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, goto out; } + /* We can bring up a flush queue without tearing down the domain */ + if (type == IOMMU_DOMAIN_DMA_FQ && prev_dom->type == IOMMU_DOMAIN_DMA) { + prev_dom->type = IOMMU_DOMAIN_DMA_FQ; + ret = iommu_dma_init_fq(prev_dom); + goto out; + } + /* Sets group->default_domain to the newly allocated domain */ ret = iommu_group_alloc_default_domain(dev->bus, group, type); if (ret) @@ -3170,9 +3177,9 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, } /* - * Changing the default domain through sysfs requires the users to ubind the - * drivers from the devices in the iommu group. Return failure if this doesn't - * meet. + * Changing the default domain through sysfs requires the users to unbind the + * drivers from the devices in the iommu group, except for a DMA -> DMA-FQ + * transition. Return failure if this isn't met. * * We need to consider the race between this and the device release path. * device_lock(dev) is used here to guarantee that the device release path @@ -3248,7 +3255,8 @@ static ssize_t iommu_group_store_type(struct iommu_group *group, /* Check if the device in the group still has a driver bound to it */ device_lock(dev); - if (device_is_bound(dev)) { + if (device_is_bound(dev) && !(req_type == IOMMU_DOMAIN_DMA_FQ && + group->default_domain->type == IOMMU_DOMAIN_DMA)) { pr_err_ratelimited("Device is still bound to driver\n"); ret = -EBUSY; goto out;