This series is a RFC for io_uring/zctap. This is an evolution of the earlier zctap work, re-targeted to use io_uring as the userspace API. The current code is intended to provide a zero-copy RX path for upper-level networking protocols (aka TCP and UDP). The current draft focuses on host-provided memory (not GPU memory). This RFC contains the upper-level core code required for operation, with the intent of soliciting feedback on the general API. This does not contain the network driver side changes required for complete operation. Also please note that as an RFC, there are some things which are incomplete or in need of rework. The intent is to use a network driver which provides header/data splitting, so the frame header (which is processed by the networking stack) does not reside in user memory. The code is roughly working (in that it has successfully received a TCP stream from a remote sender), but as an RFC, the intent is to solicit feedback on the API and overall design. The current code will also work with system pages, copying the data out to the application - this is intended as a fallback/testing path. High level description: The application allocates a frame backing store, and provides this to the kernel for use. An interface queue is requested from the networking device, and incoming frames are deposited into the provided memory region. Responsibility for correctly steering incoming frames to the queue is outside the scope of this work - it is assumed that the user has set steering rules up separately. Incoming frames are sent up the stack as skb's and eventually land in the application's socket receive queue. This differs from AF_XDP, which receives raw frames directly to userspace, without protocol processing. The RECV_ZC opcode then returns an iov[] style vector which points to the data in userspace memory. When the application has completed processing of the data, the buffer is returned back to the kernel through a fill ring for reuse. Jonathan Lemon (9): io_uring: add zctap ifq definition netdevice: add SETUP_ZCTAP to the netdev_bpf structure io_uring: add register ifq opcode io_uring: add provide_ifq_region opcode io_uring: Add io_uring zctap iov structure and helpers io_uring: introduce reference tracking for user pages. page_pool: add page allocation and free hooks. io_uring: provide functions for the page_pool. io_uring: add OP_RECV_ZC command. include/linux/io_uring.h | 24 ++ include/linux/io_uring_types.h | 10 + include/linux/netdevice.h | 6 + include/net/page_pool.h | 6 + include/uapi/linux/io_uring.h | 26 ++ io_uring/Makefile | 3 +- io_uring/io_uring.c | 10 + io_uring/kbuf.c | 13 + io_uring/kbuf.h | 2 + io_uring/net.c | 123 ++++++ io_uring/opdef.c | 23 + io_uring/zctap.c | 749 +++++++++++++++++++++++++++++++++ io_uring/zctap.h | 20 + net/core/page_pool.c | 41 +- 14 files changed, 1048 insertions(+), 8 deletions(-) create mode 100644 io_uring/zctap.c create mode 100644 io_uring/zctap.h -- 2.30.2
