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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 07CE9C43387 for ; Wed, 16 Jan 2019 17:08:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D248620675 for ; Wed, 16 Jan 2019 17:08:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391492AbfAPRIL (ORCPT ); Wed, 16 Jan 2019 12:08:11 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:37239 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731892AbfAPRIL (ORCPT ); Wed, 16 Jan 2019 12:08:11 -0500 Received: by mail-qt1-f195.google.com with SMTP id t33so7982634qtt.4; Wed, 16 Jan 2019 09:08:10 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Iut53ajDZwejWXOJq/UH8hYrcibU0xqZb3TTB/RaIWI=; b=f+16SA4we678ZL/MiUdvkBJpkBUoJJOVp+kqF7iWKKiA+zuiArJgRH51c18exwWhQF QK6W2IAQrb2vk+F9HyTKkOZnxQIbgmmUcFUARNRNs2+ffehKc5Kr70gP1WCLnYAg7ngg ykv0vCeVo4tssnjVaHBUK6EgLb+iNF6/HqxUWSVOPfadsyuEKNk/vYYEfHIYpdBfCH+d SNWfrs/vdWGAFg3kZ13gR+4eqGOC7pNClEWESiS3zw4P8RtH+9axuVfNUvjhdMequ15h 0EI4vUTZs1ubuNv2yDvpC58nWIVzEBmV6kxDYQGYsH0lATg+us0kJOPJ0LP4oKfA5ZOg IORg== X-Gm-Message-State: AJcUukcEoF4JccIJqzVIbY0PhozkXamszUmUqjzGRBKE+XsmTdYLThcn NHdJ5EZWRVGjpYlZ/ug4TaTgIW3+xJaSaUaob+A= X-Google-Smtp-Source: ALg8bN6THlJ+VDFvaDKYtxZFBUshcqjqnem21NCamdeWBDwdiEawpdBfpUSWlt7ClPKe8zigd71B5fU/VrgPz8+dbIo= X-Received: by 2002:ac8:2c34:: with SMTP id d49mr7985332qta.152.1547658489626; Wed, 16 Jan 2019 09:08:09 -0800 (PST) MIME-Version: 1.0 References: <20190116163253.23780-1-vincent.whitchurch@axis.com> In-Reply-To: <20190116163253.23780-1-vincent.whitchurch@axis.com> From: Arnd Bergmann Date: Wed, 16 Jan 2019 18:07:53 +0100 Message-ID: Subject: Re: [PATCH 0/8] Virtio-over-PCIe on non-MIC To: Vincent Whitchurch Cc: sudeep.dutt@intel.com, ashutosh.dixit@intel.com, gregkh , Linux Kernel Mailing List , Vincent Whitchurch , Kishon Vijay Abraham I , Lorenzo Pieralisi , linux-pci , linux-ntb@googlegroups.com, Jon Mason , Dave Jiang , Allen Hubbe Content-Type: text/plain; charset="UTF-8" Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Jan 16, 2019 at 5:33 PM Vincent Whitchurch wrote: > > The Virtio-over-PCIe framework living under drivers/misc/mic/vop implements a > generic framework to use virtio between two Linux systems, given shared memory > and a couple of interrupts. It does not actually require the Intel MIC > hardware, x86-64, or even PCIe for that matter. This patch series makes it > buildable on more systems and adds a loopback driver to test it without special > hardware. > > Note that I don't have access to Intel MIC hardware so some testing of the > patchset (especially the patch "vop: Use consistent DMA") on that platform > would be appreciated, to ensure that the series does not break anything there. Hi Vincent, First of all, I think it is a very good idea to make virtio over PCIe avaialable more generally. Your patches also make sense here, they mostly fix portability bugs, so no objection there. I think we need to take a step back though and discuss what combinations we actually do want to support. I have not actually read the whole mic/vop driver, so I don't know if this would be a good fit as a generic interface -- it may or may not be, and any other input would be helpful. Aside from that, I should note that we have two related subsystems in the kernel: the PCIe endpoint subsystem maintained by Kishon and Lorenzo, and the NTB subsystem maintained by Jon, Dave and Allen. In order to properly support virtio over PCIe, I would hope we can come up with a user space interface that looks the same way for configuring virtio drivers in mic, pcie-endpoint and ntb, if at all possible. Have you looked at those two subsystems? Arnd