This RFC is to demonstrate below ideas, a) Build vhost-mdev on top of the same abstraction defined in the virtio-mdev series [1]; b) Introduce /dev/vhost-mdev to do vhost ioctls and support setting mdev device as backend; Now the userspace API looks like this: - Userspace generates a compatible mdev device; - Userspace opens this mdev device with VFIO API (including doing IOMMU programming for this mdev device with VFIO's container/group based interface); - Userspace opens /dev/vhost-mdev and gets vhost fd; - Userspace uses vhost ioctls to setup vhost (userspace should do VHOST_MDEV_SET_BACKEND ioctl with VFIO group fd and device fd first before doing other vhost ioctls); Only compile test has been done for this series for now. RFCv3: https://patchwork.kernel.org/patch/11117785/ [1] https://lkml.org/lkml/2019/9/10/135 Tiwei Bie (3): vfio: support getting vfio device from device fd vfio: support checking vfio driver by device ops vhost: introduce mdev based hardware backend drivers/vfio/mdev/vfio_mdev.c | 3 +- drivers/vfio/vfio.c | 32 +++ drivers/vhost/Kconfig | 9 + drivers/vhost/Makefile | 3 + drivers/vhost/mdev.c | 462 +++++++++++++++++++++++++++++++ drivers/vhost/vhost.c | 39 ++- drivers/vhost/vhost.h | 6 + include/linux/vfio.h | 11 + include/uapi/linux/vhost.h | 10 + include/uapi/linux/vhost_types.h | 5 + 10 files changed, 573 insertions(+), 7 deletions(-) create mode 100644 drivers/vhost/mdev.c -- 2.17.1
