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X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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: Elena Ufimtseva , John G Johnson , "mst@redhat.com" , Janosch Frank , qemu-devel , Kirti Wankhede , Paolo Bonzini , Gerd Hoffmann , Yan Vugenfirer , Jag Raman , Anup Patel , Claudio Imbrenda , Christian Borntraeger , Roman Kagan , Felipe Franciosi , =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= , Jens Freimann , =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , Stefano Garzarella , Eduardo Habkost , Sergio Lopez , Kashyap Chamarthy , Darren Kenny , Liran Alon , =?UTF-8?B?QWxleCBCZW5uw6ll?= , David Gibson , Kevin Wolf , Halil Pasic , "Daniel P. Berrange" , Christophe de Dinechin , Thanos Makatos , fam Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Here are notes from the session: protocol stability: * vhost-user already exists for existing third-party applications * vfio-user is more general but will take more time to develop * libvfio-user can be provided to allow device implementations management: * Should QEMU launch device emulation processes? * Nicer user experience * Technical blockers: forking, hotplug, security is hard once QEMU has started running * Probably requires a new process model with a long-running QEMU management process proxying QMP requests to the emulator process migration: * dbus-vmstate * VFIO live migration ioctls * Source device can continue if migration fails * Opaque blobs are transferred to destination, destination can fail migration if it decides the blobs are incompatible * How does the VMM share the migration data region with the device emulation process? * The vfio-user protocol can trap or mmap * device versioning (like versioned machine types) needed to pin the guest-visible device ABI * Felipe will investigate live migration reconnection: * How to support reconnection? * QEMU has relatively little state of a vfio-user device * vhost-user has more state so it's a little easier to reconnect or migrate * Build in reconnection and live migration from the start to avoid difficulties in the future * Relationship between migration and reconnection? * VFIO has a mechanism for saving/loading device state * Lots of different reconnection cases that need to be thought through security & sandboxing: * Goal: make it easy to lock down the process so developers don't need to reinvent sandboxing * minijail * in-process * firecracker jailer * bubblewrap * launcher tool * systemd-run * launcher tool