On Fri, Jan 8, 2021 at 9:32 PM Bob Liu <bob.liu@xxxxxxxxxx> wrote: > > On 12/22/20 10:52 PM, Xie Yongji wrote: > > This VDUSE driver enables implementing vDPA devices in userspace. > > Both control path and data path of vDPA devices will be able to > > be handled in userspace. > > > > 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 VDUSE driver implements a MMU-based on-chip > > IOMMU driver which supports mapping the kernel dma buffer to a > > userspace iova region dynamically. Userspace can access those > > iova region via mmap(). Besides, the eventfd mechanism is used to > > trigger interrupt callbacks and receive virtqueue kicks in userspace > > > > Now we only support virtio-vdpa bus driver with this patch applied. > > > > Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx> > > --- > > Documentation/driver-api/vduse.rst | 74 ++ > > Documentation/userspace-api/ioctl/ioctl-number.rst | 1 + > > 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 | 442 ++++++++ > > drivers/vdpa/vdpa_user/iova_domain.h | 93 ++ > > drivers/vdpa/vdpa_user/vduse.h | 59 ++ > > drivers/vdpa/vdpa_user/vduse_dev.c | 1121 ++++++++++++++++++++ > > include/uapi/linux/vdpa.h | 1 + > > include/uapi/linux/vduse.h | 99 ++ > > 13 files changed, 2173 insertions(+) > > 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 > > > > diff --git a/Documentation/driver-api/vduse.rst b/Documentation/driver-api/vduse.rst > > new file mode 100644 > > index 000000000000..da9b3040f20a > > --- /dev/null > > +++ b/Documentation/driver-api/vduse.rst > > @@ -0,0 +1,74 @@ > > +================================== > > +VDUSE - "vDPA Device in Userspace" > > +================================== > > + > > +vDPA (virtio data path acceleration) device is a device that uses a > > +datapath which complies with the virtio specifications with vendor > > +specific control path. vDPA devices can be both physically located on > > +the hardware or emulated by software. VDUSE is a framework that makes it > > +possible to implement software-emulated vDPA devices in userspace. > > + > > Could you explain a bit more why need a VDUSE framework? This can be used to implement a userspace I/O (such as storage, network and so on) solution (virtio-based) for both container and VM. > Software emulated vDPA devices is more likely used by debugging only when > don't have real hardware. I think software emulated vDPA devices should be also useful in other cases, just like FUSE does. > Do you think do the emulation in kernel space is not enough? > Doing the emulation in userspace should be more flexible. Thanks, Yongji
