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Wed, 19 Aug 2020 06:57:35 +0000 (UTC) Subject: Re: [ovirt-devel] Re: device compatibility interface for live migration with assigned devices To: Yan Zhao , Parav Pandit References: <20200805105319.GF2177@nanopsycho> <20200810074631.GA29059@joy-OptiPlex-7040> <20200814051601.GD15344@joy-OptiPlex-7040> <20200818085527.GB20215@redhat.com> <3a073222-dcfe-c02d-198b-29f6a507b2e1@redhat.com> <20200818091628.GC20215@redhat.com> <20200818113652.5d81a392.cohuck@redhat.com> <20200819033035.GA21172@joy-OptiPlex-7040> From: Jason Wang Message-ID: Date: Wed, 19 Aug 2020 14:57:34 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200819033035.GA21172@joy-OptiPlex-7040> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Received-SPF: pass client-ip=205.139.110.120; envelope-from=jasowang@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/18 23:05:17 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "kvm@vger.kernel.org" , "libvir-list@redhat.com" , "qemu-devel@nongnu.org" , Kirti Wankhede , "eauger@redhat.com" , "xin-ran.wang@intel.com" , "corbet@lwn.net" , "openstack-discuss@lists.openstack.org" , "shaohe.feng@intel.com" , "kevin.tian@intel.com" , Parav Pandit , "jian-feng.ding@intel.com" , "dgilbert@redhat.com" , "zhenyuw@linux.intel.com" , "hejie.xu@intel.com" , "bao.yumeng@zte.com.cn" , Alex Williamson , "eskultet@redhat.com" , "sm ooney@redhat.com" , "intel-gvt-dev@lists.freedesktop.org" , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Cornelia Huck , Jiri Pirko , "dinechin@redhat.com" , "devel@ovirt.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2020/8/19 上午11:30, Yan Zhao wrote: > hi All, > could we decide that sysfs is the interface that every VFIO vendor driver > needs to provide in order to support vfio live migration, otherwise the > userspace management tool would not list the device into the compatible > list? > > if that's true, let's move to the standardizing of the sysfs interface. > (1) content > common part: (must) > - software_version: (in major.minor.bugfix scheme) This can not work for devices whose features can be negotiated/advertised independently. (E.g virtio devices) > - device_api: vfio-pci or vfio-ccw ... > - type: mdev type for mdev device or > a signature for physical device which is a counterpart for > mdev type. > > device api specific part: (must) > - pci id: pci id of mdev parent device or pci id of physical pci > device (device_api is vfio-pci)API here. So this assumes a PCI device which is probably not true. > - subchannel_type (device_api is vfio-ccw) > > vendor driver specific part: (optional) > - aggregator > - chpid_type > - remote_url For "remote_url", just wonder if it's better to integrate or reuse the existing NVME management interface instead of duplicating it here. Otherwise it could be a burden for mgmt to learn. E.g vendor A may use "remote_url" but vendor B may use a different attribute. > > NOTE: vendors are free to add attributes in this part with a > restriction that this attribute is able to be configured with the same > name in sysfs too. e.g. Sysfs works well for common attributes belongs to a class, but I'm not sure it can work well for device/vendor specific attributes. Does this mean mgmt need to iterate all the attributes in both src and dst? > for aggregator, there must be a sysfs attribute in device node > /sys/devices/pci0000:00/0000:00:02.0/882cc4da-dede-11e7-9180-078a62063ab1/intel_vgpu/aggregator, > so that the userspace tool is able to configure the target device > according to source device's aggregator attribute. > > > (2) where and structure > proposal 1: > |- [path to device] > |--- migration > | |--- self > | | |-software_version > | | |-device_api > | | |-type > | | |-[pci_id or subchannel_type] > | | |- > | |--- compatible > | | |-software_version > | | |-device_api > | | |-type > | | |-[pci_id or subchannel_type] > | | |- > multiple compatible is allowed. > attributes should be ASCII text files, preferably with only one value > per file. > > > proposal 2: use bin_attribute. > |- [path to device] > |--- migration > | |--- self > | |--- compatible > > so we can continue use multiline format. e.g. > cat compatible > software_version=0.1.0 > device_api=vfio_pci > type=i915-GVTg_V5_{val1:int:1,2,4,8} > pci_id=80865963 > aggregator={val1}/2 So basically two questions: - how hard to standardize sysfs API for dealing with compatibility check (to make it work for most types of devices) - how hard for the mgmt to learn with a vendor specific attributes (vs existing management API) Thanks > > Thanks > Yan