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=-2.3 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 9A91AC4360C for ; Fri, 27 Sep 2019 07:14:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C490207FF for ; Fri, 27 Sep 2019 07:14:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726467AbfI0HOz (ORCPT ); Fri, 27 Sep 2019 03:14:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56280 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725804AbfI0HOz (ORCPT ); Fri, 27 Sep 2019 03:14:55 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 557223090FD3; Fri, 27 Sep 2019 07:14:55 +0000 (UTC) Received: from [10.72.12.30] (ovpn-12-30.pek2.redhat.com [10.72.12.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id 52410608A5; Fri, 27 Sep 2019 07:14:44 +0000 (UTC) Subject: Re: [PATCH] vhost: introduce mdev based hardware backend To: Tiwei Bie Cc: mst@redhat.com, alex.williamson@redhat.com, maxime.coquelin@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, dan.daly@intel.com, cunming.liang@intel.com, zhihong.wang@intel.com, lingshan.zhu@intel.com References: <20190926045427.4973-1-tiwei.bie@intel.com> <1b4b8891-8c14-1c85-1d6a-2eed1c90bcde@redhat.com> <20190927045438.GA17152@___> From: Jason Wang Message-ID: <49bb0777-3761-3737-8e5b-568957f9a935@redhat.com> Date: Fri, 27 Sep 2019 15:14:42 +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: <20190927045438.GA17152@___> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Fri, 27 Sep 2019 07:14:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/27 下午12:54, Tiwei Bie wrote: >>> + >>> + /* >>> + * In vhost-mdev, userspace should pass ring addresses >>> + * in guest physical addresses when IOMMU is disabled or >>> + * IOVAs when IOMMU is enabled. >>> + */ >> A question here, consider we're using noiommu mode. If guest physical >> address is passed here, how can a device use that? >> >> I believe you meant "host physical address" here? And it also have the >> implication that the HPA should be continuous (e.g using hugetlbfs). > The comment is talking about the virtual IOMMU (i.e. iotlb in vhost). > It should be rephrased to cover the noiommu case as well. Thanks for > spotting this. So the question still, if GPA is passed how can it be used by the virtio-mdev device? Thanks