From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752020AbdJBSwm (ORCPT ); Mon, 2 Oct 2017 14:52:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39935 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336AbdJBSwk (ORCPT ); Mon, 2 Oct 2017 14:52:40 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 27D7481DFD Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=ddutile@redhat.com Subject: Re: [PATCH] uio/uio_pci_generic: Add SR-IOV support To: David Woodhouse , Alexander Duyck References: <1506517162.30379.2.camel@infradead.org> <20170927220005.GB23674@bhelgaas-glaptop.roam.corp.google.com> <1506550852.7476.33.camel@infradead.org> <1506606369.7476.96.camel@infradead.org> <7bbb6cce-3462-fbb2-9ae4-5c08ab2b01b4@redhat.com> <1506613946.7476.130.camel@infradead.org> <3ddc65bd-bf47-acb8-4cc5-db2531e1e864@redhat.com> <1506947750.18322.7.camel@infradead.org> Cc: Bjorn Helgaas , Greg Kroah-Hartman , linux-pci , linux-kernel , Alexander Duyck , "Bryant G. Ly" , Bodong Wang , Alex Williamson , "Michael S. Tsirkin" , kvm@vger.kernel.org From: Don Dutile Message-ID: <5c744ed0-2937-4460-fb8a-6e92fe5bfffa@redhat.com> Date: Mon, 2 Oct 2017 14:52:31 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1506947750.18322.7.camel@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 02 Oct 2017 18:52:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/02/2017 08:35 AM, David Woodhouse wrote: > On Thu, 2017-09-28 at 12:56 -0400, Don Dutile wrote: >> Well, my point is more like: why put it in uio? >> why not make it available via pcie, setup while/if no driver attached? >> i.e., other non-uio users can use the mechanism.... like libvirt? ... >> if a PF driver isn't required. > > This would allow you to enable SR-IOV on a PF before its driver is > loaded, right? Even when that driver *is* going to need to perform > resource management for those VFs? > > Would existing drivers cope with SR-IOV being enabled, and VFs being > assigned to guests, before they're loaded? If so then sure, let's do it > generically. But I'm not sure that's the case. > No better than a uio driver/mgmt api that may have to configure a PF before a VF is enabled. Q: So what is better: provide a common hook in sysfs for all to use, potentially causing a kernel fault (during vf probe/config), or a user-level program/mgmt-app that does the equivalent? > As it is, the UIO driver is all about "userspace knows best". So if > there's resource management to be done, then userspace needs to do that > before enabling SR-IOV. And that's consistent with the current driver- > based enabling model for SR-IOV. > I'm not seeing the UIO driver consistency here. IMO, it's a similar problem, moved to a different place. i.e., slightly different attack vector, but same endpoint.