io_uring: add memory region registration
Regions will serve multiple purposes. First, with it we can decouple
ring/etc. object creation from registration / mapping of the memory they
will be placed in. We already have hacks that allow to put both SQ and
CQ into the same huge page, in the future we should be able to:
region = create_region(io_ring);
create_pbuf_ring(io_uring, region, offset=0);
create_pbuf_ring(io_uring, region, offset=N);
The second use case is efficiently passing parameters. The following
patch enables back on top of regions IORING_ENTER_EXT_ARG_REG, which
optimises wait arguments. It'll also be useful for request arguments
replacing iovecs, msghdr, etc. pointers. Eventually it would also be
handy for BPF as well if it comes to fruition.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0798cf3a14fad19cfc96fc9feca5f3e11481691d.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 1d3a372..e1d69123 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -429,6 +429,9 @@
unsigned short n_sqe_pages;
struct page **ring_pages;
struct page **sqe_pages;
+
+ /* used for optimised request parameter and wait argument passing */
+ struct io_mapped_region param_region;
};
struct io_tw_state {
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 5cbfd33..1ee3589 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -627,6 +627,8 @@
/* resize CQ ring */
IORING_REGISTER_RESIZE_RINGS = 33,
+ IORING_REGISTER_MEM_REGION = 34,
+
/* this goes last */
IORING_REGISTER_LAST,
@@ -661,6 +663,12 @@
__u64 __resv[4];
};
+struct io_uring_mem_region_reg {
+ __u64 region_uptr; /* struct io_uring_region_desc * */
+ __u64 flags;
+ __u64 __resv[2];
+};
+
/*
* Register a fully sparse file space, rather than pass in an array of all
* -1 file descriptors.
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 286b7bb..c640b8a 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2709,6 +2709,7 @@
io_alloc_cache_free(&ctx->msg_cache, io_msg_cache_free);
io_futex_cache_free(ctx);
io_destroy_buffers(ctx);
+ io_free_region(ctx, &ctx->param_region);
mutex_unlock(&ctx->uring_lock);
if (ctx->sq_creds)
put_cred(ctx->sq_creds);
diff --git a/io_uring/register.c b/io_uring/register.c
index 3c5a3cf..2cbac3d 100644
--- a/io_uring/register.c
+++ b/io_uring/register.c
@@ -570,6 +570,37 @@
return ret;
}
+static int io_register_mem_region(struct io_ring_ctx *ctx, void __user *uarg)
+{
+ struct io_uring_mem_region_reg __user *reg_uptr = uarg;
+ struct io_uring_mem_region_reg reg;
+ struct io_uring_region_desc __user *rd_uptr;
+ struct io_uring_region_desc rd;
+ int ret;
+
+ if (io_region_is_set(&ctx->param_region))
+ return -EBUSY;
+ if (copy_from_user(®, reg_uptr, sizeof(reg)))
+ return -EFAULT;
+ rd_uptr = u64_to_user_ptr(reg.region_uptr);
+ if (copy_from_user(&rd, rd_uptr, sizeof(rd)))
+ return -EFAULT;
+
+ if (memchr_inv(®.__resv, 0, sizeof(reg.__resv)))
+ return -EINVAL;
+ if (reg.flags)
+ return -EINVAL;
+
+ ret = io_create_region(ctx, &ctx->param_region, &rd);
+ if (ret)
+ return ret;
+ if (copy_to_user(rd_uptr, &rd, sizeof(rd))) {
+ io_free_region(ctx, &ctx->param_region);
+ return -EFAULT;
+ }
+ return 0;
+}
+
static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
void __user *arg, unsigned nr_args)
__releases(ctx->uring_lock)
@@ -764,6 +795,12 @@
break;
ret = io_register_resize_rings(ctx, arg);
break;
+ case IORING_REGISTER_MEM_REGION:
+ ret = -EINVAL;
+ if (!arg || nr_args != 1)
+ break;
+ ret = io_register_mem_region(ctx, arg);
+ break;
default:
ret = -EINVAL;
break;
