On Mon, Jan 10, 2022 at 8:57 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Mon, Aug 30, 2021 at 10:17:24PM +0800, Xie Yongji wrote: > > This series introduces a framework that makes it possible to implement > > software-emulated vDPA devices in userspace. And to make the device > > emulation more secure, the emulated vDPA device's control path is handled > > in the kernel and only the data path is implemented in the userspace. > > > > Since the emuldated vDPA device's control path is handled in the kernel, > > a message mechnism is introduced to make userspace be aware of the data > > path related changes. Userspace can use read()/write() to receive/reply > > the control messages. > > > > In the data path, the core is mapping dma buffer into VDUSE daemon's > > address space, which can be implemented in different ways depending on > > the vdpa bus to which the vDPA device is attached. > > > > In virtio-vdpa case, we implements a MMU-based software IOTLB with > > bounce-buffering mechanism to achieve that. And in vhost-vdpa case, the dma > > buffer is reside in a userspace memory region which can be shared to the > > VDUSE userspace processs via transferring the shmfd. > > > > The details and our user case is shown below: > > > > ------------------------ ------------------------- ---------------------------------------------- > > | Container | | QEMU(VM) | | VDUSE daemon | > > | --------- | | ------------------- | | ------------------------- ---------------- | > > | |dev/vdx| | | |/dev/vhost-vdpa-x| | | | vDPA device emulation | | block driver | | > > ------------+----------- -----------+------------ -------------+----------------------+--------- > > | | | | > > | | | | > > ------------+---------------------------+----------------------------+----------------------+--------- > > | | block device | | vhost device | | vduse driver | | TCP/IP | | > > | -------+-------- --------+-------- -------+-------- -----+---- | > > | | | | | | > > | ----------+---------- ----------+----------- -------+------- | | > > | | virtio-blk driver | | vhost-vdpa driver | | vdpa device | | | > > | ----------+---------- ----------+----------- -------+------- | | > > | | virtio bus | | | | > > | --------+----+----------- | | | | > > | | | | | | > > | ----------+---------- | | | | > > | | virtio-blk device | | | | | > > | ----------+---------- | | | | > > | | | | | | > > | -----------+----------- | | | | > > | | virtio-vdpa driver | | | | | > > | -----------+----------- | | | | > > | | | | vdpa bus | | > > | -----------+----------------------+---------------------------+------------ | | > > | ---+--- | > > -----------------------------------------------------------------------------------------| NIC |------ > > ---+--- > > | > > ---------+--------- > > | Remote Storages | > > ------------------- > > > > We make use of it to implement a block device connecting to > > our distributed storage, which can be used both in containers and > > VMs. Thus, we can have an unified technology stack in this two cases. > > > > To test it with null-blk: > > > > $ 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/nullb0,node-name=disk0 \ > > --export type=vduse-blk,id=test,node-name=disk0,writable=on,name=vduse-null,num-queues=16,queue-size=128 > > > > The qemu-storage-daemon can be found at https://github.com/bytedance/qemu/tree/vduse > > It's been half a year - any plans to upstream this? Yeah, this is on my to-do list this month. Sorry for taking so long... I've been working on another project enabling userspace RDMA with VDUSE for the past few months. So I didn't have much time for this. Anyway, I will submit the first version as soon as possible. Thanks, Yongji
