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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 DE5CFC3A5A2 for ; Fri, 23 Aug 2019 07:19:29 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 B9FB922CF7 for ; Fri, 23 Aug 2019 07:19:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9FB922CF7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 838F0D8D; Fri, 23 Aug 2019 07:19:19 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 3074AC87 for ; Fri, 23 Aug 2019 07:19:18 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1D2EB89E for ; Fri, 23 Aug 2019 07:19:17 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Aug 2019 00:19:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,420,1559545200"; d="scan'208";a="180619613" Received: from allen-box.sh.intel.com ([10.239.159.136]) by fmsmga007.fm.intel.com with ESMTP; 23 Aug 2019 00:19:13 -0700 From: Lu Baolu To: David Woodhouse , Joerg Roedel , Bjorn Helgaas , Christoph Hellwig Subject: [PATCH v7 5/7] iommu/vt-d: Check whether device requires bounce buffer Date: Fri, 23 Aug 2019 15:17:33 +0800 Message-Id: <20190823071735.30264-6-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190823071735.30264-1-baolu.lu@linux.intel.com> References: <20190823071735.30264-1-baolu.lu@linux.intel.com> Cc: Juergen Gross , kevin.tian@intel.com, Stefano Stabellini , ashok.raj@intel.com, Konrad Rzeszutek Wilk , alan.cox@intel.com, Jonathan Corbet , Robin Murphy , Steven Rostedt , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, pengfei.xu@intel.com, Ingo Molnar , jacob.jun.pan@intel.com, Greg Kroah-Hartman , Boris Ostrovsky , mika.westerberg@linux.intel.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org This adds a helper to check whether a device needs to use bounce buffer. It also provides a boot time option to disable the bounce buffer. Users can use this to prevent the iommu driver from using the bounce buffer for performance gain. Cc: Ashok Raj Cc: Jacob Pan Cc: Kevin Tian Signed-off-by: Lu Baolu Tested-by: Xu Pengfei Tested-by: Mika Westerberg --- Documentation/admin-guide/kernel-parameters.txt | 5 +++++ drivers/iommu/intel-iommu.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 47d981a86e2f..aaca73080097 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1732,6 +1732,11 @@ Note that using this option lowers the security provided by tboot because it makes the system vulnerable to DMA attacks. + nobounce [Default off] + Disable bounce buffer for unstrusted devices such as + the Thunderbolt devices. This will treat the untrusted + devices as the trusted ones, hence might expose security + risks of DMA attacks. intel_idle.max_cstate= [KNL,HW,ACPI,X86] 0 disables intel_idle and fall back on acpi_idle. diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 8316e57f047c..b1ab3526e6fa 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -360,6 +360,7 @@ static int dmar_forcedac; static int intel_iommu_strict; static int intel_iommu_superpage = 1; static int iommu_identity_mapping; +static int intel_no_bounce; #define IDENTMAP_ALL 1 #define IDENTMAP_GFX 2 @@ -373,6 +374,8 @@ EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped); static DEFINE_SPINLOCK(device_domain_lock); static LIST_HEAD(device_domain_list); +#define device_needs_bounce(d) (!intel_no_bounce && dev_is_untrusted(d)) + /* * Iterate over elements in device_domain_list and call the specified * callback @fn against each element. @@ -455,6 +458,9 @@ static int __init intel_iommu_setup(char *str) printk(KERN_INFO "Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n"); intel_iommu_tboot_noforce = 1; + } else if (!strncmp(str, "nobounce", 8)) { + pr_info("Intel-IOMMU: No bounce buffer. This could expose security risks of DMA attacks\n"); + intel_no_bounce = 1; } str += strcspn(str, ","); -- 2.17.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu