1 files changed, 115 insertions, 0 deletions
diff --git a/include/uapi/linux/io_uring/zcrx.h b/include/uapi/linux/io_uring/zcrx.h
new file mode 100644
index 000000000000..5ce02c7a6096
--- /dev/null
+++ b/include/uapi/linux/io_uring/zcrx.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT */
+/*
+ * Header file for the io_uring zerocopy receive (zcrx) interface.
+ *
+ * Copyright (C) 2026 Pavel Begunkov
+ * Copyright (C) 2026 David Wei
+ * Copyright (C) Meta Platforms, Inc.
+ */
+#ifndef LINUX_IO_ZCRX_H
+#define LINUX_IO_ZCRX_H
+
+#include <linux/types.h>
+
+/* Zero copy receive refill queue entry */
+struct io_uring_zcrx_rqe {
+	__u64	off;
+	__u32	len;
+	__u32	__pad;
+};
+
+struct io_uring_zcrx_cqe {
+	__u64	off;
+	__u64	__pad;
+};
+
+/* The bit from which area id is encoded into offsets */
+#define IORING_ZCRX_AREA_SHIFT	48
+#define IORING_ZCRX_AREA_MASK	(~(((__u64)1 << IORING_ZCRX_AREA_SHIFT) - 1))
+
+struct io_uring_zcrx_offsets {
+	__u32	head;
+	__u32	tail;
+	__u32	rqes;
+	__u32	__resv2;
+	__u64	__resv[2];
+};
+
+enum io_uring_zcrx_area_flags {
+	IORING_ZCRX_AREA_DMABUF		= 1,
+};
+
+struct io_uring_zcrx_area_reg {
+	__u64	addr;
+	__u64	len;
+	__u64	rq_area_token;
+	__u32	flags;
+	__u32	dmabuf_fd;
+	__u64	__resv2[2];
+};
+
+enum zcrx_reg_flags {
+	ZCRX_REG_IMPORT		= 1,
+
+	/*
+	 * Register a zcrx instance without a net device. All data will be
+	 * copied. The refill queue entries might not be automatically
+	 * consumed and need to be flushed, see ZCRX_CTRL_FLUSH_RQ.
+	 */
+	ZCRX_REG_NODEV		= 2,
+};
+
+enum zcrx_features {
+	/*
+	 * The user can ask for the desired rx page size by passing the
+	 * value in struct io_uring_zcrx_ifq_reg::rx_buf_len.
+	 */
+	ZCRX_FEATURE_RX_PAGE_SIZE	= 1 << 0,
+};
+
+/*
+ * Argument for IORING_REGISTER_ZCRX_IFQ
+ */
+struct io_uring_zcrx_ifq_reg {
+	__u32	if_idx;
+	__u32	if_rxq;
+	__u32	rq_entries;
+	__u32	flags;
+
+	__u64	area_ptr; /* pointer to struct io_uring_zcrx_area_reg */
+	__u64	region_ptr; /* struct io_uring_region_desc * */
+
+	struct io_uring_zcrx_offsets offsets;
+	__u32	zcrx_id;
+	__u32	rx_buf_len;
+	__u64	__resv[3];
+};
+
+enum zcrx_ctrl_op {
+	ZCRX_CTRL_FLUSH_RQ,
+	ZCRX_CTRL_EXPORT,
+
+	__ZCRX_CTRL_LAST,
+};
+
+struct zcrx_ctrl_flush_rq {
+	__u64		__resv[6];
+};
+
+struct zcrx_ctrl_export {
+	__u32		zcrx_fd;
+	__u32 		__resv1[11];
+};
+
+struct zcrx_ctrl {
+	__u32	zcrx_id;
+	__u32	op; /* see enum zcrx_ctrl_op */
+	__u64	__resv[2];
+
+	union {
+		struct zcrx_ctrl_export		zc_export;
+		struct zcrx_ctrl_flush_rq	zc_flush;
+	};
+};
+
+#endif /* LINUX_IO_ZCRX_H */