A lot of our vhost-user stubs are large chunks of boilerplate that do (mostly) the same thing. This series attempts to fix that by defining a new base class (vhost-user-base) which is used by a generic vhost-user-device implementation. Then the rng, gpio and i2c vhost-user devices become simple specialisations of the common base defining the ID, number of queues and potentially the config handling.
In theory we could convert the rest of the vhost-user stubs but there are complications caused by the config being split between the daemon and QEMU. For example: -device vhost-user-device-pci,chardev=vus,virtio-id=8,num_vqs=3,config_size=36 works with the WIP vhost-user-scsi backend: https://github.com/rust-vmm/vhost-device/pull/301 but the concrete vhost-user-scsi-pci device fails because it expects to handle config via the command line. You will see the report: qemu-system-aarch64: -device vhost-user-scsi-pci,chardev=vus: warning: vhost-user backend supports VHOST_USER_PROTOCOL_F_CONFIG but QEMU does not. if you try. We could make the device a bit smarter but then we would need to untangle the vhost_scsi_common_() logic which is shared with the pure in kernel vhost implementation. The vhost-user-vsock stub might be another one worth re-factoring although that has a similar split architecture. The overall diffstat shows a net deletion of code as well as introducing some more documentation and moving the stubs into the common build, further reducing redundancy. Next Steps ---------- >From Stefan's last email to the v1 posting we need: vhost-user needs: - A GET_DEVICE_ID message. - A GET_CONFIG_SIZE message. Today it is assumed that the vhost-user frontend already knows the configuration space size. - A protocol feature bit indicating that the device is a full VIRTIO device. These devices also need to implement the SET_STATUS message, which is rarely implemented today. and implementing the VHOST_USER_GET_QUEUE_NUM and SET_STATUS messages to make the generic device "self configuring". Alex. Alex Bennée (13): include: attempt to document device_class_set_props include/hw: document the device_class_set_parent_* fns hw/virtio: fix typo in VIRTIO_CONFIG_IRQ_IDX comments include/hw/virtio: document virtio_notify_config include/hw/virtio: add kerneldoc for virtio_init include/hw/virtio: document some more usage of notifiers virtio: add vhost-user-base and a generic vhost-user-device virtio: add PCI stub for vhost-user-device hw/virtio: derive vhost-user-rng from vhost-user-device hw/virtio: add config support to vhost-user-device hw/virtio: derive vhost-user-gpio from vhost-user-device hw/virtio: derive vhost-user-i2c from vhost-user-base docs/system: add a basic enumeration of vhost-user devices docs/system/devices/vhost-user-rng.rst | 2 + docs/system/devices/vhost-user.rst | 41 +++ include/hw/qdev-core.h | 36 +++ include/hw/virtio/vhost-user-device.h | 46 +++ include/hw/virtio/vhost-user-gpio.h | 23 +- include/hw/virtio/vhost-user-i2c.h | 18 +- include/hw/virtio/vhost-user-rng.h | 11 +- include/hw/virtio/virtio.h | 21 ++ hw/display/vhost-user-gpu.c | 4 +- hw/net/virtio-net.c | 4 +- hw/virtio/vhost-user-device-pci.c | 71 +++++ hw/virtio/vhost-user-device.c | 380 +++++++++++++++++++++++ hw/virtio/vhost-user-fs.c | 4 +- hw/virtio/vhost-user-gpio.c | 400 ++----------------------- hw/virtio/vhost-user-i2c.c | 255 +--------------- hw/virtio/vhost-user-rng.c | 277 ++--------------- hw/virtio/vhost-vsock-common.c | 4 +- hw/virtio/virtio-crypto.c | 4 +- hw/virtio/meson.build | 20 +- 19 files changed, 686 insertions(+), 935 deletions(-) create mode 100644 include/hw/virtio/vhost-user-device.h create mode 100644 hw/virtio/vhost-user-device-pci.c create mode 100644 hw/virtio/vhost-user-device.c -- 2.39.2