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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,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 3BA0AC31E46 for ; Wed, 12 Jun 2019 07:14:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 11AC32082C for ; Wed, 12 Jun 2019 07:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408091AbfFLHOv (ORCPT ); Wed, 12 Jun 2019 03:14:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33738 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2408001AbfFLHOu (ORCPT ); Wed, 12 Jun 2019 03:14:50 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id E6B953082E90; Wed, 12 Jun 2019 07:14:49 +0000 (UTC) Received: from gondolin (ovpn-116-169.ams2.redhat.com [10.36.116.169]) by smtp.corp.redhat.com (Postfix) with ESMTP id 96C4260CD1; Wed, 12 Jun 2019 07:14:42 +0000 (UTC) Date: Wed, 12 Jun 2019 09:14:39 +0200 From: Cornelia Huck To: Alex Williamson , Halil Pasic Cc: "kvm@vger.kernel.org" , Libvirt Devel , Kirti Wankhede , Erik Skultety , Pavel Hrdina , "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" , Sylvain Bauza Subject: Re: mdevctl: A shoestring mediated device management and persistence utility Message-ID: <20190612091439.3a33f17b.cohuck@redhat.com> In-Reply-To: <20190611142822.238ef424@x1.home> References: <20190523172001.41f386d8@x1.home> <20190524121106.16e08562.cohuck@redhat.com> <20190607180630.7e8e24d4.pasic@linux.ibm.com> <20190611214508.0a86aeb2.cohuck@redhat.com> <20190611142822.238ef424@x1.home> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 12 Jun 2019 07:14:49 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 11 Jun 2019 14:28:22 -0600 Alex Williamson wrote: > On Tue, 11 Jun 2019 21:45:08 +0200 > Cornelia Huck wrote: > > > On Fri, 7 Jun 2019 18:06:30 +0200 > > Halil Pasic wrote: > > > I guess for vfio-ccw one needs to make sure that the ccw device is bound > > > to the vfio-ccw driver first, and only after that can one use > > > create-mdev to create the mdev on top of the subchannel. > > > > > > So to make this work persistently (survive a reboot) one would need to > > > take care of the subchannel getting bound to the right vfio_ccw driver > > > before mdevctl is called. Right? > > > > > > BTW how does this concurrence situation between the drivers io_subchannel > > > and vfio_ccw work? Especially if both are build in? > > > > If you have two drivers that match to the same device type, you'll > > always have the issue that the driver that is first matched with the > > device will bind to it and you have to do the unbind/rebind dance to > > get it bound to the correct device driver. (I guess that this was the > > basic motivation behind the ap bus default driver infrastructure, > > right?) I think that in our case the io_subchannel driver will be > > called first (alphabetical order and the fact that vfio-ccw will often > > be a module). I'm not sure if it is within the scope of mdevctl to > > ensure that the device is bound to the correct driver, or if it rather > > should work with devices already bound to the correct driver only. > > Maybe a separate udev-rules generator? > > Getting a device bound to a specific driver is exactly the domain of > driverctl. Implement the sysfs interfaces driverctl uses and see if it > works. Driverctl defaults to PCI and knows some extra things about > PCI, but appears to be written to be generally bus agnostic. Thanks, > > Alex Ok, looked at driverctl. Extending this one for non-PCI seems like a reasonable path. However, we would also need to extend any non-PCI device type we want to support with a driver_override attribute like you did for PCI in 782a985d7af26db39e86070d28f987cad2 -- so this is only for newer kernels. Adding that attribute for subchannels looks feasible at a glance, but I have not tried to actually do it :) Halil, do you think that would make sense? [This might also help with the lcs vs. ctc confusion on a certain 3088 cu model if this is added for ccw devices as well; but I'm not sure if these are still out in the wild at all. Probably not worth the effort for that.]