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Thu, 13 Aug 2020 15:34:15 +0000 (UTC) Received: from gondolin (ovpn-112-216.ams2.redhat.com [10.36.112.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4127F5C1A3; Thu, 13 Aug 2020 15:33:50 +0000 (UTC) Date: Thu, 13 Aug 2020 17:33:47 +0200 From: Cornelia Huck To: Sean Mooney Cc: Jiri Pirko , Yan Zhao , Jason Wang , Alex Williamson , kvm@vger.kernel.org, libvir-list@redhat.com, qemu-devel@nongnu.org, kwankhede@nvidia.com, eauger@redhat.com, xin-ran.wang@intel.com, corbet@lwn.net, openstack-discuss@lists.openstack.org, shaohe.feng@intel.com, kevin.tian@intel.com, eskultet@redhat.com, jian-feng.ding@intel.com, dgilbert@redhat.com, zhenyuw@linux.intel.com, hejie.xu@intel.com, bao.yumeng@zte.com.cn, intel-gvt-dev@lists.freedesktop.org, berrange@redhat.com, dinechin@redhat.com, devel@ovirt.org, Parav Pandit , Eric Farman Subject: Re: device compatibility interface for live migration with assigned devices Message-ID: <20200813173347.239801fa.cohuck@redhat.com> In-Reply-To: <20200807135942.5d56a202.cohuck@redhat.com> References: <20200727072440.GA28676@joy-OptiPlex-7040> <20200727162321.7097070e@x1.home> <20200729080503.GB28676@joy-OptiPlex-7040> <20200804183503.39f56516.cohuck@redhat.com> <20200805021654.GB30485@joy-OptiPlex-7040> <2624b12f-3788-7e2b-2cb7-93534960bcb7@redhat.com> <20200805075647.GB2177@nanopsycho> <20200805093338.GC30485@joy-OptiPlex-7040> <20200805105319.GF2177@nanopsycho> <4cf2824c803c96496e846c5b06767db305e9fb5a.camel@redhat.com> <20200807135942.5d56a202.cohuck@redhat.com> 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 10.5.11.16 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 7 Aug 2020 13:59:42 +0200 Cornelia Huck wrote: > On Wed, 05 Aug 2020 12:35:01 +0100 > Sean Mooney wrote: > > > On Wed, 2020-08-05 at 12:53 +0200, Jiri Pirko wrote: > > > Wed, Aug 05, 2020 at 11:33:38AM CEST, yan.y.zhao@intel.com wrote: > > (...) > > > > > software_version: device driver's version. > > > > in .[.bugfix] scheme, where there is no > > > > compatibility across major versions, minor versions have > > > > forward compatibility (ex. 1-> 2 is ok, 2 -> 1 is not) and > > > > bugfix version number indicates some degree of internal > > > > improvement that is not visible to the user in terms of > > > > features or compatibility, > > > > > > > > vendor specific attributes: each vendor may define different attributes > > > > device id : device id of a physical devices or mdev's parent pci device. > > > > it could be equal to pci id for pci devices > > > > aggregator: used together with mdev_type. e.g. aggregator=2 together > > > > with i915-GVTg_V5_4 means 2*1/4=1/2 of a gen9 Intel > > > > graphics device. > > > > remote_url: for a local NVMe VF, it may be configured with a remote > > > > url of a remote storage and all data is stored in the > > > > remote side specified by the remote url. > > > > ... > > just a minor not that i find ^ much more simmple to understand then > > the current proposal with self and compatiable. > > if i have well defiend attibute that i can parse and understand that allow > > me to calulate the what is and is not compatible that is likely going to > > more useful as you wont have to keep maintianing a list of other compatible > > devices every time a new sku is released. > > > > in anycase thank for actully shareing ^ as it make it simpler to reson about what > > you have previously proposed. > > So, what would be the most helpful format? A 'software_version' field > that follows the conventions outlined above, and other (possibly > optional) fields that have to match? Just to get a different perspective, I've been trying to come up with what would be useful for a very different kind of device, namely vfio-ccw. (Adding Eric to cc: for that.) software_version makes sense for everybody, so it should be a standard attribute. For the vfio-ccw type, we have only one vendor driver (vfio-ccw_IO). Given a subchannel A, we want to make sure that subchannel B has a reasonable chance of being compatible. I guess that means: - same subchannel type (I/O) - same chpid type (e.g. all FICON; I assume there are no 'mixed' setups -- Eric?) - same number of chpids? Maybe we can live without that and just inject some machine checks, I don't know. Same chpid numbers is something we cannot guarantee, especially if we want to migrate cross-CEC (to another machine.) Other possibly interesting information is not available at the subchannel level (vfio-ccw is a subchannel driver.) So, looking at a concrete subchannel on one of my machines, it would look something like the following: software_version=1.0.0 type=vfio-ccw <-- would be vfio-pci on the example above subchannel_type=0 chpid_type=0x1a chpid_mask=0xf0 <-- not sure if needed/wanted Does that make sense?