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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 323B5C2D0E8 for ; Thu, 26 Mar 2020 09:38:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AD5220748 for ; Thu, 26 Mar 2020 09:38:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="htiLJTEo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727843AbgCZJiL (ORCPT ); Thu, 26 Mar 2020 05:38:11 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:41818 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727738AbgCZJiK (ORCPT ); Thu, 26 Mar 2020 05:38:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=eIxU9D2p34AyD0LcFkAamRDcJSbLLbHXVWCZNZkPA64=; b=htiLJTEoNalekvmhBxZGNPfUQf 1NvDakxqrDuRl4RyY4QsQLL+5R/yN1EoFpAXTV4pr/5GkeqsGtqK+DO3zmJkGeRbpDvRN6hyTRNwl 60SlF+6JxRwhiBJGeZKZwAQodGHrcmbI6AXqa0dT1yazkJ4YItI3n9adkzzOHz+FcVNWsxOMvcwi9 ecQGHkmxmwRKUkFI3PhOGmIjLRc6OhSJ1wwGziK0AXownrW9SNSOLqvkuMC9i8ZMrorIyhbSaR8aG z3PaNAuHQ1J3BbQh7GKjJjzcHMaDUr2C1MVLnvZ2CG4wi+iLt3b0LmBAv/iG+DqDiEKTnwBlpJcyf zoKpKKBw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHOxj-0005Mq-1H; Thu, 26 Mar 2020 09:38:07 +0000 Date: Thu, 26 Mar 2020 02:38:07 -0700 From: Christoph Hellwig To: Yonghyun Hwang Cc: Christoph Hellwig , Kirti Wankhede , Alex Williamson , Cornelia Huck , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Havard Skinnemoen , Moritz Fischer Subject: Re: [PATCH] vfio-mdev: support mediated device creation in kernel Message-ID: <20200326093807.GB12078@infradead.org> References: <20200320175910.180266-1-yonghyun@google.com> <20200323111404.GA4554@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Mar 23, 2020 at 02:33:11PM -0700, Yonghyun Hwang wrote: > On Mon, Mar 23, 2020 at 4:14 AM Christoph Hellwig wrote: > > > > On Fri, Mar 20, 2020 at 10:59:10AM -0700, Yonghyun Hwang wrote: > > > To enable a mediated device, a device driver registers its device to VFIO > > > MDev framework. Once the mediated device gets enabled, UUID gets fed onto > > > the sysfs attribute, "create", to create the mediated device. This > > > additional step happens after boot-up gets complete. If the driver knows > > > how many mediated devices need to be created during probing time, the > > > additional step becomes cumbersome. This commit implements a new function > > > to allow the driver to create a mediated device in kernel. > > > > Please send this along with your proposed user so that we can understand > > the use. Without that new exports have no chance of going in anyway. > > My driver is still under development. Do you recommend me to implement > an example code for the new exports and re-submit the commit? Hell no. The point is that we don't add new APIs unless we have actual users (not example code!). And as Alex mentioned the use case is rather questionable anyway, so without a user that actually shows a good use case which would remove those doubts it is a complete no-go.