From patchwork Wed Jul 28 15:58:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 12406297 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=-17.5 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,URIBL_BLOCKED, 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 06FE4C4338F for ; Wed, 28 Jul 2021 16:14:40 +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 C1F53604DB for ; Wed, 28 Jul 2021 16:14:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C1F53604DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=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=TjthtKO08C+HGAnz/uvdk7t5VCT5iV/oxK1x2Q+iE3I=; b=zlP/tX5a0fFiGt tLF2hUnUe8UDsFHdy1CMAZsLDDz09BE9QQ8zZCkYz+VB64AZm5i5MJfBEJC5/VeptVrsULNZW4YTA FlxX+ORzry6xmY2yVf5d38yfuQsf218JpXefClTW2VBr6yv5Rg2JpYNBgcazebKnZ2mNXZRnBXTUd X7bX6kwxWvn7ju31uNuwL22y6yOxtyCq8Jn1z9iVRzwrqYGwEKZzRF6e6foWIf1ZMPiEWJ8A41ELi KluKuWDS7LZ66ATDWxgqTeqS0UE1YC1Pp24TPM09UDWwDazTaLYs42mQ/Py+ti1lBSG82TjEHCUzv BhD5oeniL3k4FL7WikSA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8mAZ-001WXn-3Q; Wed, 28 Jul 2021 16:12:31 +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 1m8lyD-001PNr-BK for linux-arm-kernel@lists.infradead.org; Wed, 28 Jul 2021 15:59:46 +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 330F613D5; Wed, 28 Jul 2021 08:59:45 -0700 (PDT) Received: from 010265703453.arm.com (unknown [10.57.36.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id AD6AC3F70D; Wed, 28 Jul 2021 08:59:43 -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 v2 22/24] iommu: Allow enabling non-strict mode dynamically Date: Wed, 28 Jul 2021 16:58:43 +0100 Message-Id: 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-20210728_085945_486808_67C555E2 X-CRM114-Status: GOOD ( 19.32 ) 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 Reviewed-by: Lu Baolu Reviewed-by: John Garry --- 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 25c1adc1ec67..be399d630953 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3200,6 +3200,13 @@ 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) @@ -3240,9 +3247,9 @@ 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 @@ -3318,7 +3325,8 @@ 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;