[PATCH net-next 03/14] net/dibs: Create net/dibs

Alexandra Winter
2025-09-05T14:54:44Z

Create an 'DIBS' shim layer that will provide generic functionality and
declarations for dibs device drivers and dibs clients.

Following patches will add functionality.

Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
---
MAINTAINERS | 7 +++++++
include/linux/dibs.h | 42 ++++++++++++++++++++++++++++++++++++++++++
net/Kconfig | 1 +
net/Makefile | 1 +
net/dibs/Kconfig | 12 ++++++++++++
net/dibs/Makefile | 7 +++++++
net/dibs/dibs_main.c | 37 +++++++++++++++++++++++++++++++++++++
7 files changed, 107 insertions(+)
create mode 100644 include/linux/dibs.h
create mode 100644 net/dibs/Kconfig
create mode 100644 net/dibs/Makefile
create mode 100644 net/dibs/dibs_main.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b81595e9ea95..c621ed92eb0e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13047,6 +13047,13 @@ F: Documentation/devicetree/bindings/hwmon/renesas,isl28022.yaml
F: Documentation/hwmon/isl28022.rst
F: drivers/hwmon/isl28022.c

+DIBS (DIRECT INTERNAL BUFFER SHARING)
+M: Alexandra Winter <wintera@linux.ibm.com>
+L: netdev@vger.kernel.org
+S: Supported
+F: include/linux/dibs.h
+F: net/dibs/
+
ISOFS FILESYSTEM
M: Jan Kara <jack@suse.cz>
L: linux-fsdevel@vger.kernel.org
diff --git a/include/linux/dibs.h b/include/linux/dibs.h
new file mode 100644
index 000000000000..3f4175aaa732
--- /dev/null
+++ b/include/linux/dibs.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Direct Internal Buffer Sharing
+ *
+ * Definitions for the DIBS module
+ *
+ * Copyright IBM Corp. 2025
+ */
+#ifndef _DIBS_H
+#define _DIBS_H
+
+/* DIBS - Direct Internal Buffer Sharing - concept
+ * -----------------------------------------------
+ * In the case of multiple system sharing the same hardware, dibs fabrics can
+ * provide dibs devices to these systems. The systems use dibs devices of the
+ * same fabric to communicate via dmbs (Direct Memory Buffers). Each dmb has
+ * exactly one owning local dibs device and one remote using dibs device, that
+ * is authorized to write into this dmb. This access control is provided by the
+ * dibs fabric.
+ *
+ * Because the access to the dmb is based on access to physical memory, it is
+ * lossless and synchronous. The remote devices can directly access any offset
+ * of the dmb.
+ *
+ * Dibs fabrics, dibs devices and dmbs are identified by tokens and ids.
+ * Dibs fabric id is unique within the same hardware (with the exception of the
+ * dibs loopback fabric), dmb token is unique within the same fabric, dibs
+ * device gids are guaranteed to be unique within the same fabric and
+ * statistically likely to be globally unique. The exchange of these tokens and
+ * ids between the systems is not part of the dibs concept.
+ *
+ * The dibs layer provides an abstraction between dibs device drivers and dibs
+ * clients.
+ */
+
+#define MAX_DIBS_CLIENTS 8
+
+struct dibs_client {
+ const char *name;
+};
+
+#endif /* _DIBS_H */
diff --git a/net/Kconfig b/net/Kconfig
index d5865cf19799..5410226f314b 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -87,6 +87,7 @@ source "net/tls/Kconfig"
source "net/xfrm/Kconfig"
source "net/iucv/Kconfig"
source "net/smc/Kconfig"
+source "net/dibs/Kconfig"
source "net/xdp/Kconfig"

config NET_HANDSHAKE
diff --git a/net/Makefile b/net/Makefile
index aac960c41db6..3e4771cfe48e 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_TIPC) += tipc/
obj-$(CONFIG_NETLABEL) += netlabel/
obj-$(CONFIG_IUCV) += iucv/
obj-$(CONFIG_SMC) += smc/
+obj-$(CONFIG_DIBS) += dibs/
obj-$(CONFIG_RFKILL) += rfkill/
obj-$(CONFIG_NET_9P) += 9p/
obj-$(CONFIG_CAIF) += caif/
diff --git a/net/dibs/Kconfig b/net/dibs/Kconfig
new file mode 100644
index 000000000000..09c12f6838ad
--- /dev/null
+++ b/net/dibs/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+config DIBS
+ tristate "DIBS support"
+ default n
+ help
+ Direct Internal Buffer Sharing (DIBS)
+ A communication method that uses common physical (internal) memory
+ for synchronous direct access into a remote buffer.
+
+ Select this option to provide the abstraction layer between
+ dibs devices and dibs clients like the SMC protocol.
+ The module name is dibs.
diff --git a/net/dibs/Makefile b/net/dibs/Makefile
new file mode 100644
index 000000000000..825dec431bfc
--- /dev/null
+++ b/net/dibs/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# DIBS class module
+#
+
+dibs-y += dibs_main.o
+obj-$(CONFIG_DIBS) += dibs.o
diff --git a/net/dibs/dibs_main.c b/net/dibs/dibs_main.c
new file mode 100644
index 000000000000..68e189932fcf
--- /dev/null
+++ b/net/dibs/dibs_main.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DIBS - Direct Internal Buffer Sharing
+ *
+ * Implementation of the DIBS class module
+ *
+ * Copyright IBM Corp. 2025
+ */
+#define KMSG_COMPONENT "dibs"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/dibs.h>
+
+MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
+MODULE_LICENSE("GPL");
+
+/* use an array rather a list for fast mapping: */
+static struct dibs_client *clients[MAX_DIBS_CLIENTS];
+static u8 max_client;
+
+static int __init dibs_init(void)
+{
+ memset(clients, 0, sizeof(clients));
+ max_client = 0;
+
+ return 0;
+}
+
+static void __exit dibs_exit(void)
+{
+}
+
+module_init(dibs_init);
+module_exit(dibs_exit);
--
2.48.1