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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 16D7ECA9EC3 for ; Thu, 31 Oct 2019 04:34:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DAD382087F for ; Thu, 31 Oct 2019 04:34:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="E0k70NUc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726370AbfJaEeC (ORCPT ); Thu, 31 Oct 2019 00:34:02 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:22174 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725816AbfJaEeC (ORCPT ); Thu, 31 Oct 2019 00:34:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572496441; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=j5qcyVpwDqk90mJ8Py1Gxg6f818uFbFkJ4UO0Lw3UAI=; b=E0k70NUcfUYOAQJlJxUhLGopP5L/VVCfIe1wsnO/d4qhBcb2T99JXOIqc1JI+3VcVOPEQL UlVZKMGk0us160ez2vpd0tkO57fV/FCbJGQDJViSrOu5Zqs+nUJccuFULdQSiMHo8XQ8/y u1nY3ZcvA7UwQNiUNb/uUQ55C0lU38g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-395-pwcln2pkOUya02HzONlt1Q-1; Thu, 31 Oct 2019 00:33:57 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 22B688017E0; Thu, 31 Oct 2019 04:33:56 +0000 (UTC) Received: from [10.72.12.100] (ovpn-12-100.pek2.redhat.com [10.72.12.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id B8616600CD; Thu, 31 Oct 2019 04:33:23 +0000 (UTC) Subject: Re: [RFC v2 00/22] intel_iommu: expose Shared Virtual Addressing to VM To: "Tian, Kevin" , "Liu, Yi L" , "qemu-devel@nongnu.org" , "mst@redhat.com" , "pbonzini@redhat.com" , "alex.williamson@redhat.com" , "peterx@redhat.com" Cc: "tianyu.lan@intel.com" , "jacob.jun.pan@linux.intel.com" , "kvm@vger.kernel.org" , "Tian, Jun J" , "eric.auger@redhat.com" , "Sun, Yi Y" , "david@gibson.dropbear.id.au" References: <1571920483-3382-1-git-send-email-yi.l.liu@intel.com> <367adad0-eb05-c950-21d7-755fffacbed6@redhat.com> From: Jason Wang Message-ID: Date: Thu, 31 Oct 2019 12:33:14 +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-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: pwcln2pkOUya02HzONlt1Q-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2019/10/25 =E4=B8=8B=E5=8D=886:12, Tian, Kevin wrote: >> From: Jason Wang [mailto:jasowang@redhat.com] >> Sent: Friday, October 25, 2019 5:49 PM >> >> >> On 2019/10/24 =E4=B8=8B=E5=8D=888:34, Liu Yi L wrote: >>> Shared virtual address (SVA), a.k.a, Shared virtual memory (SVM) on Int= el >>> platforms allow address space sharing between device DMA and >> applications. >> >> >> Interesting, so the below figure demonstrates the case of VM. I wonder >> how much differences if we compare it with doing SVM between device >> and >> an ordinary process (e.g dpdk)? >> >> Thanks > One difference is that ordinary process requires only stage-1 translation= , > while VM requires nested translation. A silly question, then I believe there's no need for VFIO DMA API in=20 this case consider the page table is shared between MMU and IOMMU? Thanks >