On Mon, Oct 19, 2020 at 10:56:19PM +0800, Xie Yongji wrote: > This series introduces a framework, which can be used to implement > vDPA Devices in a userspace program. To implement it, the work > consist of two parts: control path emulating and data path offloading. > > In the control path, the VDUSE driver will make use of message > mechnism to forward the actions (get/set features, get/st status, > get/set config space and set virtqueue states) from virtio-vdpa > driver to userspace. Userspace can use read()/write() to > receive/reply to those control messages. > > In the data path, the VDUSE driver implements a MMU-based > on-chip IOMMU driver which supports both direct mapping and > indirect mapping with bounce buffer. Then userspace can access > those iova space via mmap(). Besides, eventfd mechnism is used to > trigger interrupts and forward virtqueue kicks. > > The details and our user case is shown below: > > ------------------------ ----------------------------------------------------------- > | APP | | QEMU | > | --------- | | -------------------- -------------------+<-->+------ | > | |dev/vdx| | | | device emulation | | virtio dataplane | | BDS | | > ------------+----------- -----------+-----------------------+-----------------+----- > | | | | > | | emulating | offloading | > ------------+---------------------------+-----------------------+-----------------+------ > | | block device | | vduse driver | | vdpa device | | TCP/IP | | > | -------+-------- --------+-------- +------+------- -----+---- | > | | | | | | | > | | | | | | | > | ----------+---------- ----------+----------- | | | | > | | virtio-blk driver | | virtio-vdpa driver | | | | | > | ----------+---------- ----------+----------- | | | | > | | | | | | | > | | ------------------ | | | > | ----------------------------------------------------- ---+--- | > ------------------------------------------------------------------------------ | NIC |--- > ---+--- > | > ---------+--------- > | Remote Storages | > ------------------- > We make use of it to implement a block device connecting to > our distributed storage, which can be used in containers and > bare metal. What is not exactly clear is what is the APP above doing. Taking virtio blk requests and sending them over the network in some proprietary way? > Compared with qemu-nbd solution, this solution has > higher performance, and we can have an unified technology stack > in VM and containers for remote storages. > > To test it with a host disk (e.g. /dev/sdx): > > $ qemu-storage-daemon \ > --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server,nowait \ > --monitor chardev=charmonitor \ > --blockdev driver=host_device,cache.direct=on,aio=native,filename=/dev/sdx,node-name=disk0 \ > --export vduse-blk,id=test,node-name=disk0,writable=on,vduse-id=1,num-queues=16,queue-size=128 > > The qemu-storage-daemon can be found at https://github.com/bytedance/qemu/tree/vduse > > Future work: > - Improve performance (e.g. zero copy implementation in datapath) > - Config interrupt support > - Userspace library (find a way to reuse device emulation code in qemu/rust-vmm) How does this driver compare with vhost-user-blk (which doesn't need kernel support)? > Xie Yongji (4): > mm: export zap_page_range() for driver use > vduse: Introduce VDUSE - vDPA Device in Userspace > vduse: grab the module's references until there is no vduse device > vduse: Add memory shrinker to reclaim bounce pages > > drivers/vdpa/Kconfig | 8 + > drivers/vdpa/Makefile | 1 + > drivers/vdpa/vdpa_user/Makefile | 5 + > drivers/vdpa/vdpa_user/eventfd.c | 221 ++++++ > drivers/vdpa/vdpa_user/eventfd.h | 48 ++ > drivers/vdpa/vdpa_user/iova_domain.c | 488 ++++++++++++ > drivers/vdpa/vdpa_user/iova_domain.h | 104 +++ > drivers/vdpa/vdpa_user/vduse.h | 66 ++ > drivers/vdpa/vdpa_user/vduse_dev.c | 1081 ++++++++++++++++++++++++++ > include/uapi/linux/vduse.h | 85 ++ > mm/memory.c | 1 + > 11 files changed, 2108 insertions(+) > create mode 100644 drivers/vdpa/vdpa_user/Makefile > create mode 100644 drivers/vdpa/vdpa_user/eventfd.c > create mode 100644 drivers/vdpa/vdpa_user/eventfd.h > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.c > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.h > create mode 100644 drivers/vdpa/vdpa_user/vduse.h > create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c > create mode 100644 include/uapi/linux/vduse.h > > -- > 2.25.1
