Add two kfuncs that should cover most of the needs:
1. bpf_io_uring_submit_sqes(), which allows to submit io_uring requests.
It mirrors the normal user space submission path and follows all
related io_uring_enter(2) rules. i.e. SQEs are taken from the SQ
according to head/tail values. In case of IORING_SETUP_SQ_REWIND,
it'll submit first N entries.
2. bpf_io_uring_get_region() returns a pointer to the specified region,
where io_uring regions are kernel-userspace shared chunks of memory.
It takes the size as an argument, which should be a load time
constant. There are 3 types of regions:
- IOU_REGION_SQ returns the submission queue.
- IOU_REGION_CQ stores the CQ, SQ/CQ headers and the sqarray. In
other words, it gives same memory that would normally be mmap'ed
with IORING_FEAT_SINGLE_MMAP enabled IORING_OFF_SQ_RING.
- IOU_REGION_MEM represents the memory / parameter region. It can be
used to store request indirect parameters and for kernel - user
communication.
It intentionally provides a thin but flexible API and expects BPF
programs to implement CQ/SQ header parsing, CQ walking, etc. That
mirrors how the normal user space works with rings and should help
to minimise kernel / kfunc helpers changes while introducing new generic
io_uring features.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/967bcc10e94c796eb273998621551b2a21848cde.1772109579.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce io_uring BPF struct ops implementing the loop_step callback,
which will allow BPF to overwrite the default io_uring event loop logic.
The callback takes an io_uring context, the main role of which is to be
passed to io_uring kfuncs. The other argument is a struct iou_loop_params,
which BPF can use to request CQ waiting and communicate other parameters.
See the event loop description in the previous patch for more details.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/98db437651ce64e9cbeb611c60bf5887259db09f.1772109579.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
