Received: by 2002:ad5:474a:0:0:0:0:0 with SMTP id i10csp6141825imu; Wed, 30 Jan 2019 09:27:58 -0800 (PST) X-Google-Smtp-Source: ALg8bN7CNmoaNhYLsTm+gh+FWjRWmRVp6cWq459OhBQwwdNcyTrTj0C91RT09fmVn4KxISPGUB9F X-Received: by 2002:a65:4683:: with SMTP id h3mr27145716pgr.225.1548869278209; Wed, 30 Jan 2019 09:27:58 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1548869278; cv=none; d=google.com; s=arc-20160816; b=pj92WurrcXPtYHh5mYJ6oqPSzur89LUeD9kheYX3nDBbBMTX2lVlfihLDAItKC9Nri oV+h9uLe6gJKvi6txGckrJV+JZxvdEWyRsJGJoT/uhMvBc9I0iY39/Cv2NW5e4pejl5s DLz9fq8Dqcuh5O7Hig6sqLK4LyOmkSockp/tYzk0naVQpnjmUZshOdllBStFisq1GA/t iBBj2y1iV7TmprvX9CULq4A33fmR8PjFkgZAJZohLzG53QKQ4iONYMidn0zc9DNNb6Sb lN9W2JK45dNcUw2ezUSLWik2Frfmt0mqh4hV5iPxjjnbyJliK45MGTLpFchEEepHLI4C oNAg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=GVhgu25msCq7s4/zPu4AurVArGf7VhGY30MRUFDioto=; b=gLox0jl7g4qhpDyCaK5iYN1fgW/WyOAh5R7nsyiQto1RtSmLKCObTweVyioopArrNT abyO8yGkN0b9YlB6vY0wNIUhBm9beUmC+RcmGYnxcftcNynjhHPwZrXYTVaKY7INo0HY FR2UGU3wM5i+hRU7bGyUraYGqDWRzs+M7Hp4BgALJD14cnzTSw3bU/NeqXFKGlMXKzaW WuiKftTdxN1BFsRSJDCe2czxgZZ4J60r3WhZicUKC2Yieoy/lkq1bBAdNHjsk471kMMz F1l8A8Rf/WV+y57Ar/bbddPhkeOGlodLb9o5krNtIqWLVVvimGWd3IC6ejBVRjEyr6k2 xDLA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o192si1798965pgo.129.2019.01.30.09.27.39; Wed, 30 Jan 2019 09:27:58 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732545AbfA3R05 (ORCPT + 99 others); Wed, 30 Jan 2019 12:26:57 -0500 Received: from verein.lst.de ([213.95.11.211]:53115 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728998AbfA3R0z (ORCPT ); Wed, 30 Jan 2019 12:26:55 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id A292768CEC; Wed, 30 Jan 2019 18:26:53 +0100 (CET) Date: Wed, 30 Jan 2019 18:26:53 +0100 From: Christoph Hellwig To: Jerome Glisse Cc: "Koenig, Christian" , Christoph Hellwig , Jason Gunthorpe , Logan Gunthorpe , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Greg Kroah-Hartman , "Rafael J . Wysocki" , Bjorn Helgaas , "Kuehling, Felix" , "linux-pci@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Marek Szyprowski , Robin Murphy , Joerg Roedel , "iommu@lists.linux-foundation.org" Subject: Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma Message-ID: <20190130172653.GA6707@lst.de> References: <20190129174728.6430-1-jglisse@redhat.com> <20190129174728.6430-4-jglisse@redhat.com> <20190129191120.GE3176@redhat.com> <20190129193250.GK10108@mellanox.com> <99c228c6-ef96-7594-cb43-78931966c75d@deltatee.com> <20190129205827.GM10108@mellanox.com> <20190130080208.GC29665@lst.de> <4e0637ba-0d7c-66a5-d3de-bc1e7dc7c0ef@amd.com> <20190130155543.GC3177@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190130155543.GC3177@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 30, 2019 at 10:55:43AM -0500, Jerome Glisse wrote: > Even outside GPU driver, device driver like RDMA just want to share their > doorbell to other device and they do not want to see those doorbell page > use in direct I/O or anything similar AFAICT. At least Mellanox HCA support and inline data feature where you can copy data directly into the BAR. For something like a usrspace NVMe target it might be very useful to do direct I/O straight into the BAR for that.