From: Pavel Begunkov <asml.silence@gmail.com>

Introduce IORING_REGISTER_ZCRX_CTRL and add some boilerplate code
forwarding it to zcrx. There are no actual users in this patch, it'll be
used for refill queue flushing and other features.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 include/uapi/linux/io_uring.h | 13 +++++++++++++
 io_uring/register.c           |  3 +++
 io_uring/zcrx.c               | 21 ++++++++++++++++++++-
 io_uring/zcrx.h               |  7 +++----
 4 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e96080db3e4d..8b4935b983e7 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -697,6 +697,9 @@ enum io_uring_register_op {
 	/* query various aspects of io_uring, see linux/io_uring/query.h */
 	IORING_REGISTER_QUERY			= 35,
 
+	/* auxiliary zcrx configuration, see enum zcrx_ctrl_op */
+	IORING_REGISTER_ZCRX_CTRL		= 36,
+
 	/* this goes last */
 	IORING_REGISTER_LAST,
 
@@ -1078,6 +1081,16 @@ struct io_uring_zcrx_ifq_reg {
 	__u64	__resv[3];
 };
 
+enum zcrx_ctrl_op {
+	__ZCRX_CTRL_LAST,
+};
+
+struct zcrx_ctrl {
+	__u32	zcrx_id;
+	__u32	op; /* see enum zcrx_ctrl_op */
+	__u64	resv[8];
+};
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/io_uring/register.c b/io_uring/register.c
index d8ce1b5cc3a2..38b20a7a34db 100644
--- a/io_uring/register.c
+++ b/io_uring/register.c
@@ -826,6 +826,9 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 	case IORING_REGISTER_QUERY:
 		ret = io_query(ctx, arg, nr_args);
 		break;
+	case IORING_REGISTER_ZCRX_CTRL:
+		ret = io_zcrx_ctrl(ctx, arg, nr_args);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index b694fa582d29..3e9d8333a301 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -541,6 +541,25 @@ struct io_mapped_region *io_zcrx_get_region(struct io_ring_ctx *ctx,
 	return ifq ? &ifq->region : NULL;
 }
 
+int io_zcrx_ctrl(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args)
+{
+	struct zcrx_ctrl ctrl;
+	struct io_zcrx_ifq *ifq;
+
+	if (nr_args)
+		return -EINVAL;
+	if (copy_from_user(&ctrl, arg, sizeof(ctrl)))
+		return -EFAULT;
+	if (ctrl.op >= __ZCRX_CTRL_LAST)
+		return -EOPNOTSUPP;
+
+	ifq = xa_load(&ctx->zcrx_ctxs, ctrl.zcrx_id);
+	if (!ifq)
+		return -ENXIO;
+
+	return -EINVAL;
+}
+
 int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 			  struct io_uring_zcrx_ifq_reg __user *arg)
 {
@@ -966,7 +985,7 @@ static void io_return_buffers(struct io_zcrx_ifq *ifq,
 }
 
 __maybe_unused
-int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
+static int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
 			void __user *arg, unsigned nr_arg)
 {
 	struct io_uring_zcrx_rqe rqes[IO_ZCRX_SYS_REFILL_BATCH];
diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h
index 33ef61503092..d7bef619e8ad 100644
--- a/io_uring/zcrx.h
+++ b/io_uring/zcrx.h
@@ -63,8 +63,7 @@ struct io_zcrx_ifq {
 };
 
 #if defined(CONFIG_IO_URING_ZCRX)
-int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
-			void __user *arg, unsigned nr_arg);
+int io_zcrx_ctrl(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_arg);
 int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 			 struct io_uring_zcrx_ifq_reg __user *arg);
 void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx);
@@ -97,8 +96,8 @@ static inline struct io_mapped_region *io_zcrx_get_region(struct io_ring_ctx *ct
 {
 	return NULL;
 }
-static inline int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
-				      void __user *arg, unsigned nr_arg)
+static inline int io_zcrx_ctrl(struct io_ring_ctx *ctx,
+			       void __user *arg, unsigned nr_arg)
 {
 	return -EOPNOTSUPP;
 }
-- 
2.47.3