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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 1459EC4320D for ; Wed, 25 Sep 2019 02:50:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF61B2146E for ; Wed, 25 Sep 2019 02:50:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2633758AbfIYCue (ORCPT ); Tue, 24 Sep 2019 22:50:34 -0400 Received: from mga04.intel.com ([192.55.52.120]:25296 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404590AbfIYCud (ORCPT ); Tue, 24 Sep 2019 22:50:33 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Sep 2019 19:50:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,546,1559545200"; d="scan'208";a="201100050" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga002.jf.intel.com with ESMTP; 24 Sep 2019 19:50:29 -0700 Cc: baolu.lu@linux.intel.com, Joerg Roedel , David Woodhouse , Alex Williamson , "Kumar, Sanjay K" , "Liu, Yi L" , "Sun, Yi Y" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH 0/4] Use 1st-level for DMA remapping in guest To: "Tian, Kevin" , "Raj, Ashok" , Jacob Pan References: <20190923122454.9888-1-baolu.lu@linux.intel.com> <20190923122715.53de79d0@jacob-builder> <20190923202552.GA21816@araj-mobl1.jf.intel.com> From: Lu Baolu Message-ID: Date: Wed, 25 Sep 2019 10:48:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Kevin, On 9/24/19 3:00 PM, Tian, Kevin wrote: >>>> '-----------' >>>> '-----------' >>>> >>>> This patch series only aims to achieve the first goal, a.k.a using > first goal? then what are other goals? I didn't spot such information. > The overall goal is to use IOMMU nested mode to avoid shadow page table and VMEXIT when map an gIOVA. This includes below 4 steps (maybe not accurate, but you could get the point.) 1) GIOVA mappings over 1st-level page table; 2) binding vIOMMU 1st level page table to the pIOMMU; 3) using pIOMMU second level for GPA->HPA translation; 4) enable nested (a.k.a. dual stage) translation in host. This patch set aims to achieve 1). > Also earlier you mentioned the new approach (nested) is more secure > than shadowing. why? > My bad! After reconsideration, I realized that it's not "more secure". Thanks for pointing this out. Best regards, Baolu