On Wed, Jul 6, 2022 at 1:05 PM Xie Yongji <xieyongji@xxxxxxxxxxxxx> wrote: > > Hi all, > > This series introduces some new ioctls: VDUSE_IOTLB_GET_INFO, > VDUSE_IOTLB_REG_UMEM and VDUSE_IOTLB_DEREG_UMEM to support > registering and de-registering userspace memory for IOTLB > as bounce buffer in virtio-vdpa case. > > The VDUSE_IOTLB_GET_INFO ioctl can help user to query IOLTB > information such as bounce buffer size. Then user can use > those information on VDUSE_IOTLB_REG_UMEM and > VDUSE_IOTLB_DEREG_UMEM ioctls to register and de-register > userspace memory for IOTLB. > > During registering and de-registering, the DMA data in use > would be copied from kernel bounce pages to userspace bounce > pages and back. > > With this feature, some existing application such as SPDK > and DPDK can leverage the datapath of VDUSE directly and > efficiently as discussed before [1][2]. They can register > some preallocated hugepages to VDUSE to avoid an extra > memcpy from bounce-buffer to hugepages. This is really interesting. But a small concern on uAPI is that this seems to expose the VDUSE internal implementation (bounce buffer) to userspace. We tried hard to hide it via the GET_FD before. Anyway can we keep it? Thanks > > The kernel and userspace codes could be found in github: > > https://github.com/bytedance/linux/tree/vduse-umem > https://github.com/bytedance/qemu/tree/vduse-umem > > To test it with qemu-storage-daemon: > > $ qemu-storage-daemon \ > --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server=on,wait=off \ > --monitor chardev=charmonitor \ > --blockdev driver=host_device,cache.direct=on,aio=native,filename=/dev/nullb0,node-name=disk0 \ > --export type=vduse-blk,id=vduse-test,name=vduse-test,node-name=disk0,writable=on > > [1] https://lkml.org/lkml/2021/6/27/318 > [2] https://lkml.org/lkml/2022/7/4/246 > > Please review, thanks! > > V1 to V2: > - Drop the patch that updating API version [MST] > - Replace unpin_user_pages() with unpin_user_pages_dirty_lock() [MST] > - Use __vmalloc(__GFP_ACCOUNT) for memory accounting [MST] > > Xie Yongji (5): > vduse: Remove unnecessary spin lock protection > vduse: Use memcpy_{to,from}_page() in do_bounce() > vduse: Support using userspace pages as bounce buffer > vduse: Support querying IOLTB information > vduse: Support registering userspace memory for IOTLB > > drivers/vdpa/vdpa_user/iova_domain.c | 134 ++++++++++++++++++++--- > drivers/vdpa/vdpa_user/iova_domain.h | 9 ++ > drivers/vdpa/vdpa_user/vduse_dev.c | 152 +++++++++++++++++++++++++++ > include/uapi/linux/vduse.h | 45 ++++++++ > 4 files changed, 327 insertions(+), 13 deletions(-) > > -- > 2.20.1 > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
