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 95498C43603 for ; Tue, 17 Dec 2019 01:20:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B8242082E for ; Tue, 17 Dec 2019 01:20:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726641AbfLQBUI (ORCPT ); Mon, 16 Dec 2019 20:20:08 -0500 Received: from mga06.intel.com ([134.134.136.31]:26552 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbfLQBUI (ORCPT ); Mon, 16 Dec 2019 20:20:08 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Dec 2019 17:20:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,323,1571727600"; d="scan'208";a="227316776" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by orsmga002.jf.intel.com with ESMTP; 16 Dec 2019 17:20:03 -0800 Cc: baolu.lu@linux.intel.com, "Raj, Ashok" , "Kumar, Sanjay K" , "jacob.jun.pan@linux.intel.com" , "Tian, Kevin" , "Sun, Yi Y" , Peter Xu , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3 5/6] iommu/vt-d: Flush PASID-based iotlb for iova over first level To: "Liu, Yi L" , Joerg Roedel , David Woodhouse , Alex Williamson References: <20191211021219.8997-1-baolu.lu@linux.intel.com> <20191211021219.8997-6-baolu.lu@linux.intel.com> From: Lu Baolu Message-ID: <6a5f6695-d1fd-e7d1-3ea3-f222a1ef0e54@linux.intel.com> Date: Tue, 17 Dec 2019 09:19:12 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yi, On 12/15/19 5:22 PM, Liu, Yi L wrote: > Ok, let me explain more... default pasid is meaningful only when > the domain has been attached to a device as an aux-domain. right? No exactly. Each domain has a specific default pasid, no matter normal domain (RID based) or aux-domain (PASID based). The difference is for a normal domain RID2PASID value is used, for an aux-domain the pasid is allocated from a global pool. The same concept used in VT-d 3.x scalable mode. For RID based DMA translation RID2PASID value is used when walking the tables; For PASID based DMA translation a real pasid in the transaction is used. > If a domain only has one device, and it is attached to this device as > normal domain (normal domain means non aux-domain here). Then > you should flush cache with domain-id and RID2PASID value. > If a domain has one device, and it is attached to this device as > aux-domain. Then you may want to flush cache with domain-id > and default pasid. right? A domain's counterpart is IOMMU group. So we say attach/detach domain to/from devices in a group. We don't allow devices with different default pasid sitting in a same group, right? > Then let's come to the case I mentioned in previous email. a mdev > and another device assigned to a single VM. In host, you will have > a domain which has two devices, one device(deva) is attached as No. We will have two IOMMU groups and two domains. Correct me if my understanding is not right. Best regards, baolu > normal domain, another one (devB) is attached as aux-domain. Then > which pasid should be used when the mapping in IOVA page table is > modified? RID2PASID or default pasid? I think both should be used > since the domain means differently to the two devices. If you just > use default pasid, then deva may still be able to use stale caches. > > Regards, > Yi Liu