On Wed, Dec 04, 2024 at 09:21:48AM -0800, David Wei wrote:
> From: David Wei <davidhwei@xxxxxxxx>
>
> Add a new object called an interface queue (ifq) that represents a net
> rx queue that has been configured for zero copy. Each ifq is registered
> using a new registration opcode IORING_REGISTER_ZCRX_IFQ.
>
> The refill queue is allocated by the kernel and mapped by userspace
> using a new offset IORING_OFF_RQ_RING, in a similar fashion to the main
> SQ/CQ. It is used by userspace to return buffers that it is done with,
> which will then be re-used by the netdev again.
>
> The main CQ ring is used to notify userspace of received data by using
> the upper 16 bytes of a big CQE as a new struct io_uring_zcrx_cqe. Each
> entry contains the offset + len to the data.
>
> For now, each io_uring instance only has a single ifq.
>
> Signed-off-by: David Wei <dw@xxxxxxxxxxx>
...
> diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
...
> +int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
> + struct io_uring_zcrx_ifq_reg __user *arg)
> +{
> + struct io_uring_zcrx_ifq_reg reg;
> + struct io_uring_region_desc rd;
> + struct io_zcrx_ifq *ifq;
> + size_t ring_sz, rqes_sz;
> + int ret;
> +
> + /*
> + * 1. Interface queue allocation.
> + * 2. It can observe data destined for sockets of other tasks.
> + */
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + /* mandatory io_uring features for zc rx */
> + if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN &&
> + ctx->flags & IORING_SETUP_CQE32))
> + return -EINVAL;
> + if (ctx->ifq)
> + return -EBUSY;
> + if (copy_from_user(®, arg, sizeof(reg)))
> + return -EFAULT;
> + if (copy_from_user(&rd, u64_to_user_ptr(reg.region_ptr), sizeof(rd)))
> + return -EFAULT;
> + if (memchr_inv(®.__resv, 0, sizeof(reg.__resv)))
> + return -EINVAL;
> + if (reg.if_rxq == -1 || !reg.rq_entries || reg.flags)
> + return -EINVAL;
> + if (reg.rq_entries > IO_RQ_MAX_ENTRIES) {
> + if (!(ctx->flags & IORING_SETUP_CLAMP))
> + return -EINVAL;
> + reg.rq_entries = IO_RQ_MAX_ENTRIES;
> + }
> + reg.rq_entries = roundup_pow_of_two(reg.rq_entries);
> +
> + if (!reg.area_ptr)
> + return -EFAULT;
> +
> + ifq = io_zcrx_ifq_alloc(ctx);
> + if (!ifq)
> + return -ENOMEM;
> +
> + ret = io_allocate_rbuf_ring(ifq, ®, &rd);
> + if (ret)
> + goto err;
> +
> + ifq->rq_entries = reg.rq_entries;
> + ifq->if_rxq = reg.if_rxq;
> +
> + ring_sz = sizeof(struct io_uring);
> + rqes_sz = sizeof(struct io_uring_zcrx_rqe) * ifq->rq_entries;
Hi David,
A minor nit from my side: rqes_sz is set but otherwise unused in this
function. Perhaps it can be removed?
Flagged by W=1 builds.
> + reg.offsets.rqes = ring_sz;
> + reg.offsets.head = offsetof(struct io_uring, head);
> + reg.offsets.tail = offsetof(struct io_uring, tail);
> +
> + if (copy_to_user(arg, ®, sizeof(reg)) ||
> + copy_to_user(u64_to_user_ptr(reg.region_ptr), &rd, sizeof(rd))) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + ctx->ifq = ifq;
> + return 0;
> +err:
> + io_zcrx_ifq_free(ifq);
> + return ret;
> +}
...
