[PATCH V3 04/12] io_uring: prepare for extending io_uring with bpf

[Ming Lei <ming.lei@redhat.com>]

Add one bpf operation & related framework and prepare for extending io_uring
with bpf.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/uapi/linux/io_uring.h |  1 +
 init/Kconfig                  |  7 +++++++
 io_uring/Makefile             |  1 +
 io_uring/bpf_ext.c            | 26 ++++++++++++++++++++++++++
 io_uring/bpf_ext.h            | 15 +++++++++++++++
 io_uring/opdef.c              | 16 ++++++++++++++++
 6 files changed, 66 insertions(+)
 create mode 100644 io_uring/bpf_ext.c
 create mode 100644 io_uring/bpf_ext.h

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index c10c4827f6b0..cb1e888761c3 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -318,6 +318,7 @@ enum io_uring_op {
 	IORING_OP_PIPE,
 	IORING_OP_NOP128,
 	IORING_OP_URING_CMD128,
+	IORING_OP_BPF,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
diff --git a/init/Kconfig b/init/Kconfig
index 444ce811ea67..c4587cf46765 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1884,6 +1884,13 @@ config IO_URING
 	  applications to submit and complete IO through submission and
 	  completion rings that are shared between the kernel and application.
 
+config IO_URING_BPF_EXT
+	bool "Enable IO uring bpf extension" if EXPERT
+	depends on IO_URING && BPF
+	help
+	  This option enables bpf extension for the io_uring interface, so
+	  application can define its own io_uring operation by bpf program.
+
 config GCOV_PROFILE_URING
 	bool "Enable GCOV profiling on the io_uring subsystem"
 	depends on IO_URING && GCOV_KERNEL
diff --git a/io_uring/Makefile b/io_uring/Makefile
index c54e328d1410..f540ba5d777e 100644
--- a/io_uring/Makefile
+++ b/io_uring/Makefile
@@ -26,3 +26,4 @@ obj-$(CONFIG_PROC_FS) += fdinfo.o
 obj-$(CONFIG_IO_URING_MOCK_FILE) += mock_file.o
 obj-$(CONFIG_IO_URING_BPF) += bpf_filter.o
 obj-$(CONFIG_IO_URING_BPF_OPS) += bpf-ops.o
+obj-$(CONFIG_IO_URING_BPF_EXT)	+= bpf_ext.o
diff --git a/io_uring/bpf_ext.c b/io_uring/bpf_ext.c
new file mode 100644
index 000000000000..146f70054c0a
--- /dev/null
+++ b/io_uring/bpf_ext.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Red Hat */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <uapi/linux/io_uring.h>
+#include "io_uring.h"
+#include "bpf_ext.h"
+
+int io_uring_bpf_issue(struct io_kiocb *req, unsigned int issue_flags)
+{
+	return -EOPNOTSUPP;
+}
+
+int io_uring_bpf_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return -EOPNOTSUPP;
+}
+
+void io_uring_bpf_fail(struct io_kiocb *req)
+{
+}
+
+void io_uring_bpf_cleanup(struct io_kiocb *req)
+{
+}
diff --git a/io_uring/bpf_ext.h b/io_uring/bpf_ext.h
new file mode 100644
index 000000000000..179530ce865b
--- /dev/null
+++ b/io_uring/bpf_ext.h
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef IOU_BPF_OP_H
+#define IOU_BPF_OP_H
+
+struct io_kiocb;
+struct io_uring_sqe;
+
+#ifdef CONFIG_IO_URING_BPF_EXT
+int io_uring_bpf_issue(struct io_kiocb *req, unsigned int issue_flags);
+int io_uring_bpf_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_uring_bpf_fail(struct io_kiocb *req);
+void io_uring_bpf_cleanup(struct io_kiocb *req);
+#endif
+
+#endif
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index c3ef52b70811..451500c61917 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -38,6 +38,7 @@
 #include "futex.h"
 #include "truncate.h"
 #include "zcrx.h"
+#include "bpf_ext.h"
 
 static int io_no_issue(struct io_kiocb *req, unsigned int issue_flags)
 {
@@ -589,6 +590,14 @@ const struct io_issue_def io_issue_defs[] = {
 		.prep			= io_uring_cmd_prep,
 		.issue			= io_uring_cmd,
 	},
+	[IORING_OP_BPF] = {
+#if defined(CONFIG_IO_URING_BPF_EXT)
+		.prep			= io_uring_bpf_prep,
+		.issue			= io_uring_bpf_issue,
+#else
+		.prep			= io_eopnotsupp_prep,
+#endif
+	},
 };
 
 const struct io_cold_def io_cold_defs[] = {
@@ -847,6 +856,13 @@ const struct io_cold_def io_cold_defs[] = {
 		.sqe_copy		= io_uring_cmd_sqe_copy,
 		.cleanup		= io_uring_cmd_cleanup,
 	},
+	[IORING_OP_BPF] = {
+		.name			= "BPF",
+#if defined(CONFIG_IO_URING_BPF_EXT)
+		.cleanup		= io_uring_bpf_cleanup,
+		.fail			= io_uring_bpf_fail,
+#endif
+	},
 };
 
 const char *io_uring_get_opcode(u8 opcode)
-- 
2.53.0