On 2020/12/22 下午10:52, Xie Yongji wrote:
This series introduces a framework, which can be used to implement
vDPA Devices in a userspace program. The work consist of two parts:
control path forwarding and data path offloading.
In the control path, the VDUSE driver will make use of message
mechnism to forward the config operation from vdpa bus driver
to userspace. Userspace can use read()/write() to receive/reply
those 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 on-chip IOMMU driver with
bounce-buffering mechanism to achieve that.
Rethink about the bounce buffer stuffs. I wonder instead of using kernel
pages with mmap(), how about just use userspace pages like what vhost did?
It means we need a worker to do bouncing but we don't need to care about
annoying stuffs like page reclaiming?
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 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)
This is now based on below series:
https://lore.kernel.org/netdev/20201112064005.349268-1-parav@xxxxxxxxxx/
V1 to V2:
- Add vhost-vdpa support
I may miss something but I don't see any code to support that. E.g
neither set_map nor dma_map/unmap is implemented in the config ops.
Thanks
- Add some documents
- Based on the vdpa management tool
- Introduce a workqueue for irq injection
- Replace interval tree with array map to store the iova_map
Xie Yongji (13):
mm: export zap_page_range() for driver use
eventfd: track eventfd_signal() recursion depth separately in different cases
eventfd: Increase the recursion depth of eventfd_signal()
vdpa: Remove the restriction that only supports virtio-net devices
vdpa: Pass the netlink attributes to ops.dev_add()
vduse: Introduce VDUSE - vDPA Device in Userspace
vduse: support get/set virtqueue state
vdpa: Introduce process_iotlb_msg() in vdpa_config_ops
vduse: Add support for processing vhost iotlb message
vduse: grab the module's references until there is no vduse device
vduse/iova_domain: Support reclaiming bounce pages
vduse: Add memory shrinker to reclaim bounce pages
vduse: Introduce a workqueue for irq injection
Documentation/driver-api/vduse.rst | 91 ++
Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
drivers/vdpa/Kconfig | 8 +
drivers/vdpa/Makefile | 1 +
drivers/vdpa/vdpa.c | 2 +-
drivers/vdpa/vdpa_sim/vdpa_sim.c | 3 +-
drivers/vdpa/vdpa_user/Makefile | 5 +
drivers/vdpa/vdpa_user/eventfd.c | 229 ++++
drivers/vdpa/vdpa_user/eventfd.h | 48 +
drivers/vdpa/vdpa_user/iova_domain.c | 517 ++++++++
drivers/vdpa/vdpa_user/iova_domain.h | 103 ++
drivers/vdpa/vdpa_user/vduse.h | 59 +
drivers/vdpa/vdpa_user/vduse_dev.c | 1373 ++++++++++++++++++++
drivers/vhost/vdpa.c | 34 +-
fs/aio.c | 3 +-
fs/eventfd.c | 20 +-
include/linux/eventfd.h | 5 +-
include/linux/vdpa.h | 11 +-
include/uapi/linux/vdpa.h | 1 +
include/uapi/linux/vduse.h | 119 ++
mm/memory.c | 1 +
21 files changed, 2598 insertions(+), 36 deletions(-)
create mode 100644 Documentation/driver-api/vduse.rst
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
