From 2647e2ecc096d2330d6b6a34a3a1f0a99828c14c Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 13 Nov 2025 10:48:57 +0000 Subject: io_uring/query: introduce zcrx query Add a new query type IO_URING_QUERY_ZCRX returning the user some basic information about the interface, which includes allowed flags for areas and registration and supported IORING_REGISTER_ZCRX_CTRL subcodes. There is also a chicken-egg problem with user provided refill queue memory, where offsets and size information is returned after registration, but to properly allocate memory you need to know it beforehand, which is why the userspace currently has to guess the RQ headers size and severely overestimates it. Return the size information. It's split into "size" and "alignment" fields because for default placement modes the user is interested in the aligned size, however if it gets support for more flexible placement, it'll need to only know the actual header size. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- io_uring/query.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'io_uring/query.c') diff --git a/io_uring/query.c b/io_uring/query.c index e1435cdc2665..6f9fa5153903 100644 --- a/io_uring/query.c +++ b/io_uring/query.c @@ -4,9 +4,11 @@ #include "query.h" #include "io_uring.h" +#include "zcrx.h" union io_query_data { struct io_uring_query_opcode opcodes; + struct io_uring_query_zcrx zcrx; }; #define IO_MAX_QUERY_SIZE sizeof(union io_query_data) @@ -27,6 +29,20 @@ static ssize_t io_query_ops(union io_query_data *data) return sizeof(*e); } +static ssize_t io_query_zcrx(union io_query_data *data) +{ + struct io_uring_query_zcrx *e = &data->zcrx; + + e->register_flags = ZCRX_REG_IMPORT; + e->area_flags = IORING_ZCRX_AREA_DMABUF; + e->nr_ctrl_opcodes = __ZCRX_CTRL_LAST; + e->rq_hdr_size = sizeof(struct io_uring); + e->rq_hdr_alignment = L1_CACHE_BYTES; + e->__resv1 = 0; + e->__resv2 = 0; + return sizeof(*e); +} + static int io_handle_query_entry(struct io_ring_ctx *ctx, union io_query_data *data, void __user *uhdr, u64 *next_entry) @@ -55,6 +71,9 @@ static int io_handle_query_entry(struct io_ring_ctx *ctx, case IO_URING_QUERY_OPCODES: ret = io_query_ops(data); break; + case IO_URING_QUERY_ZCRX: + ret = io_query_zcrx(data); + break; } if (ret >= 0) { -- cgit From 4aaa9bc4d5921363490d95fe66c4db086a915799 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 13 Nov 2025 10:48:58 +0000 Subject: io_uring/query: introduce rings info query Same problem as with zcrx in the previous patch, the user needs to know SQ/CQ header sizes to allocated memory before setup to use it for user provided rings, i.e. IORING_SETUP_NO_MMAP, however that information is only returned after registration, hence the user is guessing kernel implementation details. Return the header size and alignment, which is split with the same motivation, to allow the user to know the real structure size without alignment in case there will be more flexible placement schemes in the future. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- io_uring/query.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'io_uring/query.c') diff --git a/io_uring/query.c b/io_uring/query.c index 6f9fa5153903..e61b6221f87f 100644 --- a/io_uring/query.c +++ b/io_uring/query.c @@ -9,6 +9,7 @@ union io_query_data { struct io_uring_query_opcode opcodes; struct io_uring_query_zcrx zcrx; + struct io_uring_query_scq scq; }; #define IO_MAX_QUERY_SIZE sizeof(union io_query_data) @@ -43,6 +44,15 @@ static ssize_t io_query_zcrx(union io_query_data *data) return sizeof(*e); } +static ssize_t io_query_scq(union io_query_data *data) +{ + struct io_uring_query_scq *e = &data->scq; + + e->hdr_size = sizeof(struct io_rings); + e->hdr_alignment = SMP_CACHE_BYTES; + return sizeof(*e); +} + static int io_handle_query_entry(struct io_ring_ctx *ctx, union io_query_data *data, void __user *uhdr, u64 *next_entry) @@ -74,6 +84,9 @@ static int io_handle_query_entry(struct io_ring_ctx *ctx, case IO_URING_QUERY_ZCRX: ret = io_query_zcrx(data); break; + case IO_URING_QUERY_SCQ: + ret = io_query_scq(data); + break; } if (ret >= 0) { -- cgit