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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CA45CC48BE6 for ; Sat, 12 Jun 2021 01:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6A3E61246 for ; Sat, 12 Jun 2021 01:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230331AbhFLBYE (ORCPT ); Fri, 11 Jun 2021 21:24:04 -0400 Received: from mga14.intel.com ([192.55.52.115]:27949 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229942AbhFLBYE (ORCPT ); Fri, 11 Jun 2021 21:24:04 -0400 IronPort-SDR: SHfz12V4XM5GN/V3nwuTVG1Wmh7khPlWkwM6xa0ally7u2cMlRA9cuyPXkAnOf0uhr+WdOuanJ zffATOqw/iEg== X-IronPort-AV: E=McAfee;i="6200,9189,10012"; a="205453110" X-IronPort-AV: E=Sophos;i="5.83,268,1616482800"; d="scan'208";a="205453110" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jun 2021 18:22:05 -0700 IronPort-SDR: HGSyKzehp43FjYp0rgwHlcVfxC/9mqaKeNAcAIonOHPHnDnfDerhV26RKa823oHg4ZqVAypTei ihffYAKT/tTA== X-IronPort-AV: E=Sophos;i="5.83,268,1616482800"; d="scan'208";a="483464843" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.238.4.20]) ([10.238.4.20]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jun 2021 18:22:02 -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 To: John Garry , joro@8bytes.org, will@kernel.org, dwmw2@infradead.org, robin.murphy@arm.com References: <1623414043-40745-1-git-send-email-john.garry@huawei.com> <1623414043-40745-3-git-send-email-john.garry@huawei.com> From: Lu Baolu Subject: Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options Message-ID: Date: Sat, 12 Jun 2021 09:21:59 +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: <1623414043-40745-3-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/6/11 20:20, John Garry wrote: > +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 mapping finally being torn down in the IOMMU, where the > + device can still access the system memory. However this mode may " ... and the mappings cached in the IOMMU IOTLB or device TLB finally being invalidated, where the device probably can still access the memory which has already been unmapped by the device driver." Best regards, baolu