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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,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 6851FC2D0FB for ; Wed, 13 May 2020 02:30:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4969E23127 for ; Wed, 13 May 2020 02:30:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CVOy29ss" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727082AbgEMCaC (ORCPT ); Tue, 12 May 2020 22:30:02 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:22452 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727890AbgEMCaB (ORCPT ); Tue, 12 May 2020 22:30:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589337000; 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=iT2hW+HYXkczOFTWfJmASn4ajF5YSjXsGJSRKP6B8QY=; b=CVOy29ssTBBUdBgXdE6VGpH7W+32DF86LhZcriuK6XUqjTXm0lLcpqLBfKGRGVxanBDBAP M5xKKo6ucy8eMs3JiMePsGcmTRrOSBGCn9EY1prNu/9QwebPIFPE4I8JLIGRmWp0sC8DnO AQGFIpIvZSkhqW9DlvuDICG8SwBEf8g= 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-281-EmZXlPFvPpqAhwBszIdqLA-1; Tue, 12 May 2020 22:29:56 -0400 X-MC-Unique: EmZXlPFvPpqAhwBszIdqLA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 18B981005510; Wed, 13 May 2020 02:29:53 +0000 (UTC) Received: from [10.72.13.188] (ovpn-13-188.pek2.redhat.com [10.72.13.188]) by smtp.corp.redhat.com (Postfix) with ESMTP id 189CC60BF1; Wed, 13 May 2020 02:29:32 +0000 (UTC) Subject: Re: [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver. To: Jason Gunthorpe , "Raj, Ashok" Cc: "Tian, Kevin" , Alex Williamson , "Jiang, Dave" , "vkoul@kernel.org" , "megha.dey@linux.intel.com" , "maz@kernel.org" , "bhelgaas@google.com" , "rafael@kernel.org" , "gregkh@linuxfoundation.org" , "tglx@linutronix.de" , "hpa@zytor.com" , "Pan, Jacob jun" , "Liu, Yi L" , "Lu, Baolu" , "Kumar, Sanjay K" , "Luck, Tony" , "Lin, Jing" , "Williams, Dan J" , "kwankhede@nvidia.com" , "eric.auger@redhat.com" , "parav@mellanox.com" , "dmaengine@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "linux-pci@vger.kernel.org" , "kvm@vger.kernel.org" , Paolo Bonzini References: <20200426191357.GB13640@mellanox.com> <20200426214355.29e19d33@x1.home> <20200427115818.GE13640@mellanox.com> <20200427071939.06aa300e@x1.home> <20200427132218.GG13640@mellanox.com> <20200508204710.GA78778@otc-nc-03> <20200508231610.GO19158@mellanox.com> <20200509000909.GA79981@otc-nc-03> <20200509122113.GP19158@mellanox.com> From: Jason Wang Message-ID: <196b23b9-12f7-2fc2-5efb-22e0642c456a@redhat.com> Date: Wed, 13 May 2020 10:29:31 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200509122113.GP19158@mellanox.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On 2020/5/9 下午8:21, Jason Gunthorpe wrote: > On Fri, May 08, 2020 at 05:09:09PM -0700, Raj, Ashok wrote: >> Hi Jason >> >> On Fri, May 08, 2020 at 08:16:10PM -0300, Jason Gunthorpe wrote: >>> On Fri, May 08, 2020 at 01:47:10PM -0700, Raj, Ashok wrote: >>> >>>> Even when uaccel was under development, one of the options >>>> was to use VFIO as the transport, goal was the same i.e to keep >>>> the user space have one interface. >>> I feel a bit out of the loop here, uaccel isn't in today's kernel is >>> it? I've heard about it for a while, it sounds very similar to RDMA, >>> so I hope they took some of my advice... >> I think since 5.7 maybe? drivers/misc/uacce. I don't think this is like >> RDMA, its just a plain accelerator. There is no connection management, >> memory registration or other things.. IB was my first job at Intel, >> but saying that i would be giving my age away:) > rdma was the first thing to do kernel bypass, all this stuff is like > rdma at some level.. I see this looks like the 'warp driver' stuff > redone > > Wow, lots wrong here. Oh well. > >>> putting emulation code back into them, except in a more dangerous >>> kernel location. This does not seem like a net win to me. >> Its not a whole lot of emulation right? mdev are soft partitioned. There is >> just a single PF, but we can create a separate partition for the guest using >> PASID along with the normal BDF (RID). And exposing a consistent PCI like >> interface to user space you get everything else for free. >> >> Yes, its not SRIOV, but giving that interface to user space via VFIO, we get >> all of that functionality without having to reinvent a different way to do it. >> >> vDPA went the other way, IRC, they went and put a HW implementation of what >> virtio is in hardware. So they sort of fit the model. Here the instance >> looks and feels like real hardware for the setup and control aspect. > VDPA and this are very similar, of course it depends on the exact HW > implementation. > > Jason Actually this is not a must. Technically we can do ring/descriptor translation in the vDPA driver as what zerocopy AF_XDP did. Thanks >