Merge branch 'dibs-direct-internal-buffer-sharing'

Alexandra Winter says:

====================
dibs - Direct Internal Buffer Sharing

This series introduces a generic abstraction of existing components like:
- the s390 specific ISM device (Internal Shared Memory),
- the SMC-D loopback mechanism (Shared Memory Communication - Direct)
- the client interface of the SMC-D module to the transport devices
This generic shim layer can be extended with more devices, more clients and
more features in the future.

This layer is called 'dibs' for Direct Internal Buffer Sharing based on the
common scheme that these mechanisms enable controlled sharing of memory
buffers within some containing entity such as a hypervisor or a Linux
instance.

Benefits:
- Cleaner separation of ISM and SMC-D functionality
- simpler and less module dependencies
- Clear interface definition.
- Extendable for future devices and clients.

An overview was given at the Netdev 0x19 conference, recordings and slides
are available [1].

Background / Status quo:
------------------------
Currently s390 hardware provides virtual PCI ISM devices (Internal Shared
Memory). Their driver is in drivers/s390/net/ism_drv.c. The main user is
SMC-D (net/smc). The ism driver offers a client interface so other
users/protocols can also use them, but it is still heavily intermingled
with the smc code. Namely, the ism module cannot be used without the smc
module, which feels artificial.

There is ongoing work to extend the ISM concept of shared buffers that can
be accessed directly by another instance on the same hardware: [2] proposed
a loopback interface (ism_lo), that can be used on non-s390 architectures
(e.g. between containers or to test SMC-D). A minimal implementation went
upstream with [3]: ism_lo currently is a part of the smc protocol and
rather hidden.

[4] proposed a virtio definition of ism (ism_virtio) that can be used
between kvm guests.

We will shortly send an RFC for an dibs client that uses dibs as transport
for TTY.

Concept:
--------
Create a shim layer in net/dibs that contains common definitions and code
for all dibs devices and all dibs clients. Any device or client module only
needs to depend on this dibs layer module and any device or client code
only needs to include the definitions in include/linux/dibs.h.

The name dibs was chosen to clearly distinguish it from the existing s390
ism devices. And to emphasize that it is not about sharing whole memory
regions with anybody, but dedicating single buffers for another system.

Implementation:
---------------
The end result of this series is: A dibs shim layer with
- One dibs client: smc-d
- Two dibs device drivers: ism and dibs-loopback
- Everything prepared to add more clients and more device drivers.

Patches 1-2 contain some issues that were found along the way. They make
sense on their own, but also enable a better structured dibs series.

There are three components that exist today:
a) smc module (especially SMC-D functionality, which is an ism client today)
b) ism device driver (supports multiple ism clients today)
c) smc-loopback (integrated with smc today)
In order to preserve existing functionality at each step, these are not
moved to dibs layer by component, instead:
- the dibs layer is established in parallel to existing code [patches 3-6]
- then some service functions are moved to the dibs layer [patches 7-12]
- the actual data movement is moved to the dibs layer [patch 13]
- and last event handling is moved to the dibs layer [patch 14]

Future:
-------
Items that are not part of this patchset but can be added later:
- dynamically add or remove dibs_loopback. That will be allow for simple
testing of add_dev()/del_dev()
- handle_irq(): Call clients without interrupt context. e.g using
threaded interrupts. I left this for a follow-on, because it includes
conceptual changes for the smcd receive code.
- Any improvements of locking scopes. I mainly moved some of the the
existing locks to dibs layer. I have the feeling there is room for
improvements.
- The device drivers should not loop through the client array
- dibs_dev_op.*_dmb() functions reveal unnecessary details of the
internal dmb struct to the clients
- Check whether client calls to dibs_dev_ops should be replaced by
interface functions that provide additional value
- Check whether device driver calls to dibs_client_ops should be replaced
by interface functions that provide additional value.

Link: [1] https://netdevconf.info/0x19/sessions/talk/communication-via-internal-shared-memory-ism-time-to-open-up.html
Link: [2] https://lore.kernel.org/netdev/[e-mail]/
Link: [3] https://lore.kernel.org/linux-kernel//[e-mail]/
Link: [4] https://groups.oasis-open.org/communities/community-home/digestviewer/viewthread?GroupId=3973&MessageKey=c060ecf9-ea1a-49a2-9827-c92f0e6447b2&CommunityKey=2f26be99-3aa1-48f6-93a5-018dce262226&hlmlt=VT
====================

Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

MAINTAINERS

···
 S:	Maintained
 F:	drivers/gpio/gpio-gpio-mm.c
 
+DIBS (DIRECT INTERNAL BUFFER SHARING)
+M:	Alexandra Winter <[e-mail]>
+L:	[e-mail]
+S:	Supported
+F:	drivers/dibs/
+F:	include/linux/dibs.h
+
 DIGITEQ AUTOMOTIVE MGB4 V4L2 DRIVER
 M:	Martin Tuma <[e-mail]>
 L:	[e-mail]
···
 F:	include/linux/hippidevice.h
 F:	include/linux/if_*
 F:	include/linux/inetdevice.h
-F:	include/linux/ism.h
 F:	include/linux/netdev*
 F:	include/linux/platform_data/wiznet.h
 F:	include/uapi/linux/cn_proc.h
···
 L:	[e-mail]
 S:	Supported
 F:	drivers/s390/net/
-F:	include/linux/ism.h
 
 S390 PCI SUBSYSTEM
 M:	Niklas Schnelle <[e-mail]>

arch/s390/configs/debug_defconfig

···
 CONFIG_UNIX_DIAG=m
 CONFIG_XFRM_USER=m
 CONFIG_NET_KEY=m
+CONFIG_DIBS=y
+CONFIG_DIBS_LO=y
+CONFIG_SMC=m
 CONFIG_SMC_DIAG=m
-CONFIG_SMC_LO=y
 CONFIG_INET=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_ADVANCED_ROUTER=y

arch/s390/configs/defconfig

···
 CONFIG_UNIX_DIAG=m
 CONFIG_XFRM_USER=m
 CONFIG_NET_KEY=m
+CONFIG_DIBS=y
+CONFIG_DIBS_LO=y
+CONFIG_SMC=m
 CONFIG_SMC_DIAG=m
-CONFIG_SMC_LO=y
 CONFIG_INET=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_ADVANCED_ROUTER=y

drivers/Makefile

···
 obj-$(CONFIG_CDX_BUS)		+= cdx/
 obj-$(CONFIG_DPLL)		+= dpll/
 
+obj-$(CONFIG_DIBS)		+= dibs/
 obj-$(CONFIG_S390)		+= s390/

drivers/dibs/Kconfig

···
+# 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.
+
+config DIBS_LO
+	bool "intra-OS shortcut with dibs loopback"
+	depends on DIBS
+	default n
+	help
+	  DIBS_LO enables the creation of an software-emulated dibs device
+	  named lo which can be used for transferring data when communication
+	  occurs within the same OS. This helps in convenient testing of
+	  dibs clients, since dibs loopback is independent of architecture or
+	  hardware.

drivers/dibs/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# DIBS class module
+#
+
+dibs-y += dibs_main.o
+obj-$(CONFIG_DIBS) += dibs.o
+dibs-$(CONFIG_DIBS_LO) += dibs_loopback.o

drivers/dibs/dibs_loopback.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Functions for dibs loopback/loopback-ism device.
+ *
+ *  Copyright (c) 2024, Alibaba Inc.
+ *
+ *  Author: Wen Gu <[e-mail]>
+ *          Tony Lu <[e-mail]>
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/dibs.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "dibs_loopback.h"
+
+#define DIBS_LO_SUPPORT_NOCOPY	0x1
+#define DIBS_DMA_ADDR_INVALID	(~(dma_addr_t)0)
+
+static const char dibs_lo_dev_name[] = "lo";
+/* global loopback device */
+static struct dibs_lo_dev *lo_dev;
+
+static u16 dibs_lo_get_fabric_id(struct dibs_dev *dibs)
+{
+	return DIBS_LOOPBACK_FABRIC;
+}
+
+static int dibs_lo_query_rgid(struct dibs_dev *dibs, const uuid_t *rgid,
+			      u32 vid_valid, u32 vid)
+{
+	/* rgid should be the same as lgid */
+	if (!uuid_equal(rgid, &dibs->gid))
+		return -ENETUNREACH;
+	return 0;
+}
+
+static int dibs_lo_max_dmbs(void)
+{
+	return DIBS_LO_MAX_DMBS;
+}
+
+static int dibs_lo_register_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb,
+				struct dibs_client *client)
+{
+	struct dibs_lo_dmb_node *dmb_node, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	unsigned long flags;
+	int sba_idx, rc;
+
+	ldev = dibs->drv_priv;
+	sba_idx = dmb->idx;
+	/* check space for new dmb */
+	for_each_clear_bit(sba_idx, ldev->sba_idx_mask, DIBS_LO_MAX_DMBS) {
+		if (!test_and_set_bit(sba_idx, ldev->sba_idx_mask))
+			break;
+	}
+	if (sba_idx == DIBS_LO_MAX_DMBS)
+		return -ENOSPC;
+
+	dmb_node = kzalloc(sizeof(*dmb_node), GFP_KERNEL);
+	if (!dmb_node) {
+		rc = -ENOMEM;
+		goto err_bit;
+	}
+
+	dmb_node->sba_idx = sba_idx;
+	dmb_node->len = dmb->dmb_len;
+	dmb_node->cpu_addr = kzalloc(dmb_node->len, GFP_KERNEL |
+				     __GFP_NOWARN | __GFP_NORETRY |
+				     __GFP_NOMEMALLOC);
+	if (!dmb_node->cpu_addr) {
+		rc = -ENOMEM;
+		goto err_node;
+	}
+	dmb_node->dma_addr = DIBS_DMA_ADDR_INVALID;
+	refcount_set(&dmb_node->refcnt, 1);
+
+again:
+	/* add new dmb into hash table */
+	get_random_bytes(&dmb_node->token, sizeof(dmb_node->token));
+	write_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_node->token) {
+		if (tmp_node->token == dmb_node->token) {
+			write_unlock_bh(&ldev->dmb_ht_lock);
+			goto again;
+		}
+	}
+	hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
+	write_unlock_bh(&ldev->dmb_ht_lock);
+	atomic_inc(&ldev->dmb_cnt);
+
+	dmb->idx = dmb_node->sba_idx;
+	dmb->dmb_tok = dmb_node->token;
+	dmb->cpu_addr = dmb_node->cpu_addr;
+	dmb->dma_addr = dmb_node->dma_addr;
+	dmb->dmb_len = dmb_node->len;
+
+	spin_lock_irqsave(&dibs->lock, flags);
+	dibs->dmb_clientid_arr[sba_idx] = client->id;
+	spin_unlock_irqrestore(&dibs->lock, flags);
+
+	return 0;
+
+err_node:
+	kfree(dmb_node);
+err_bit:
+	clear_bit(sba_idx, ldev->sba_idx_mask);
+	return rc;
+}
+
+static void __dibs_lo_unregister_dmb(struct dibs_lo_dev *ldev,
+				     struct dibs_lo_dmb_node *dmb_node)
+{
+	/* remove dmb from hash table */
+	write_lock_bh(&ldev->dmb_ht_lock);
+	hash_del(&dmb_node->list);
+	write_unlock_bh(&ldev->dmb_ht_lock);
+
+	clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
+	kfree(dmb_node->cpu_addr);
+	kfree(dmb_node);
+
+	if (atomic_dec_and_test(&ldev->dmb_cnt))
+		wake_up(&ldev->ldev_release);
+}
+
+static int dibs_lo_unregister_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	unsigned long flags;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb from hash table */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+		if (tmp_node->token == dmb->dmb_tok) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+	if (!dmb_node)
+		return -EINVAL;
+
+	if (refcount_dec_and_test(&dmb_node->refcnt)) {
+		spin_lock_irqsave(&dibs->lock, flags);
+		dibs->dmb_clientid_arr[dmb_node->sba_idx] = NO_DIBS_CLIENT;
+		spin_unlock_irqrestore(&dibs->lock, flags);
+
+		__dibs_lo_unregister_dmb(ldev, dmb_node);
+	}
+	return 0;
+}
+
+static int dibs_lo_support_dmb_nocopy(struct dibs_dev *dibs)
+{
+	return DIBS_LO_SUPPORT_NOCOPY;
+}
+
+static int dibs_lo_attach_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb_node according to dmb->dmb_tok */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+		if (tmp_node->token == dmb->dmb_tok) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!dmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (!refcount_inc_not_zero(&dmb_node->refcnt))
+		/* the dmb is being unregistered, but has
+		 * not been removed from the hash table.
+		 */
+		return -EINVAL;
+
+	/* provide dmb information */
+	dmb->idx = dmb_node->sba_idx;
+	dmb->dmb_tok = dmb_node->token;
+	dmb->cpu_addr = dmb_node->cpu_addr;
+	dmb->dma_addr = dmb_node->dma_addr;
+	dmb->dmb_len = dmb_node->len;
+	return 0;
+}
+
+static int dibs_lo_detach_dmb(struct dibs_dev *dibs, u64 token)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb_node according to dmb->dmb_tok */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, token) {
+		if (tmp_node->token == token) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!dmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (refcount_dec_and_test(&dmb_node->refcnt))
+		__dibs_lo_unregister_dmb(ldev, dmb_node);
+	return 0;
+}
+
+static int dibs_lo_move_data(struct dibs_dev *dibs, u64 dmb_tok,
+			     unsigned int idx, bool sf, unsigned int offset,
+			     void *data, unsigned int size)
+{
+	struct dibs_lo_dmb_node *rmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	u16 s_mask;
+	u8 client_id;
+	u32 sba_idx;
+
+	ldev = dibs->drv_priv;
+
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
+		if (tmp_node->token == dmb_tok) {
+			rmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!rmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	memcpy((char *)rmb_node->cpu_addr + offset, data, size);
+	sba_idx = rmb_node->sba_idx;
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (!sf)
+		return 0;
+
+	spin_lock(&dibs->lock);
+	client_id = dibs->dmb_clientid_arr[sba_idx];
+	s_mask = ror16(0x1000, idx);
+	if (likely(client_id != NO_DIBS_CLIENT && dibs->subs[client_id]))
+		dibs->subs[client_id]->ops->handle_irq(dibs, sba_idx, s_mask);
+	spin_unlock(&dibs->lock);
+
+	return 0;
+}
+
+static const struct dibs_dev_ops dibs_lo_ops = {
+	.get_fabric_id = dibs_lo_get_fabric_id,
+	.query_remote_gid = dibs_lo_query_rgid,
+	.max_dmbs = dibs_lo_max_dmbs,
+	.register_dmb = dibs_lo_register_dmb,
+	.unregister_dmb = dibs_lo_unregister_dmb,
+	.move_data = dibs_lo_move_data,
+	.support_mmapped_rdmb = dibs_lo_support_dmb_nocopy,
+	.attach_dmb = dibs_lo_attach_dmb,
+	.detach_dmb = dibs_lo_detach_dmb,
+};
+
+static void dibs_lo_dev_init(struct dibs_lo_dev *ldev)
+{
+	rwlock_init(&ldev->dmb_ht_lock);
+	hash_init(ldev->dmb_ht);
+	atomic_set(&ldev->dmb_cnt, 0);
+	init_waitqueue_head(&ldev->ldev_release);
+}
+
+static void dibs_lo_dev_exit(struct dibs_lo_dev *ldev)
+{
+	if (atomic_read(&ldev->dmb_cnt))
+		wait_event(ldev->ldev_release, !atomic_read(&ldev->dmb_cnt));
+}
+
+static int dibs_lo_dev_probe(void)
+{
+	struct dibs_lo_dev *ldev;
+	struct dibs_dev *dibs;
+	int ret;
+
+	ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
+	if (!ldev)
+		return -ENOMEM;
+
+	dibs = dibs_dev_alloc();
+	if (!dibs) {
+		kfree(ldev);
+		return -ENOMEM;
+	}
+
+	ldev->dibs = dibs;
+	dibs->drv_priv = ldev;
+	dibs_lo_dev_init(ldev);
+	uuid_gen(&dibs->gid);
+	dibs->ops = &dibs_lo_ops;
+
+	dibs->dev.parent = NULL;
+	dev_set_name(&dibs->dev, "%s", dibs_lo_dev_name);
+
+	ret = dibs_dev_add(dibs);
+	if (ret)
+		goto err_reg;
+	lo_dev = ldev;
+	return 0;
+
+err_reg:
+	kfree(dibs->dmb_clientid_arr);
+	/* pairs with dibs_dev_alloc() */
+	put_device(&dibs->dev);
+	kfree(ldev);
+
+	return ret;
+}
+
+static void dibs_lo_dev_remove(void)
+{
+	if (!lo_dev)
+		return;
+
+	dibs_dev_del(lo_dev->dibs);
+	dibs_lo_dev_exit(lo_dev);
+	/* pairs with dibs_dev_alloc() */
+	put_device(&lo_dev->dibs->dev);
+	kfree(lo_dev);
+	lo_dev = NULL;
+}
+
+int dibs_loopback_init(void)
+{
+	return dibs_lo_dev_probe();
+}
+
+void dibs_loopback_exit(void)
+{
+	dibs_lo_dev_remove();
+}

drivers/dibs/dibs_loopback.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  dibs loopback (aka loopback-ism) device structure definitions.
+ *
+ *  Copyright (c) 2024, Alibaba Inc.
+ *
+ *  Author: Wen Gu <[e-mail]>
+ *          Tony Lu <[e-mail]>
+ *
+ */
+
+#ifndef _DIBS_LOOPBACK_H
+#define _DIBS_LOOPBACK_H
+
+#include <linux/dibs.h>
+#include <linux/hashtable.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#if IS_ENABLED(CONFIG_DIBS_LO)
+#define DIBS_LO_DMBS_HASH_BITS	12
+#define DIBS_LO_MAX_DMBS	5000
+
+struct dibs_lo_dmb_node {
+	struct hlist_node list;
+	u64 token;
+	u32 len;
+	u32 sba_idx;
+	void *cpu_addr;
+	dma_addr_t dma_addr;
+	refcount_t refcnt;
+};
+
+struct dibs_lo_dev {
+	struct dibs_dev *dibs;
+	atomic_t dmb_cnt;
+	rwlock_t dmb_ht_lock;
+	DECLARE_BITMAP(sba_idx_mask, DIBS_LO_MAX_DMBS);
+	DECLARE_HASHTABLE(dmb_ht, DIBS_LO_DMBS_HASH_BITS);
+	wait_queue_head_t ldev_release;
+};
+
+int dibs_loopback_init(void);
+void dibs_loopback_exit(void);
+#else
+static inline int dibs_loopback_init(void)
+{
+	return 0;
+}
+
+static inline void dibs_loopback_exit(void)
+{
+}
+#endif
+
+#endif /* _DIBS_LOOPBACK_H */

drivers/dibs/dibs_main.c

···
+// 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/slab.h>
+#include <linux/err.h>
+#include <linux/dibs.h>
+
+#include "dibs_loopback.h"
+
+MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
+MODULE_LICENSE("GPL");
+
+static struct class *dibs_class;
+
+/* use an array rather a list for fast mapping: */
+static struct dibs_client *clients[MAX_DIBS_CLIENTS];
+static u8 max_client;
+static DEFINE_MUTEX(clients_lock);
+struct dibs_dev_list {
+	struct list_head list;
+	struct mutex mutex; /* protects dibs device list */
+};
+
+static struct dibs_dev_list dibs_dev_list = {
+	.list = LIST_HEAD_INIT(dibs_dev_list.list),
+	.mutex = __MUTEX_INITIALIZER(dibs_dev_list.mutex),
+};
+
+static void dibs_setup_forwarding(struct dibs_client *client,
+				  struct dibs_dev *dibs)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dibs->lock, flags);
+	dibs->subs[client->id] = client;
+	spin_unlock_irqrestore(&dibs->lock, flags);
+}
+
+int dibs_register_client(struct dibs_client *client)
+{
+	struct dibs_dev *dibs;
+	int i, rc = -ENOSPC;
+
+	mutex_lock(&dibs_dev_list.mutex);
+	mutex_lock(&clients_lock);
+	for (i = 0; i < MAX_DIBS_CLIENTS; ++i) {
+		if (!clients[i]) {
+			clients[i] = client;
+			client->id = i;
+			if (i == max_client)
+				max_client++;
+			rc = 0;
+			break;
+		}
+	}
+	mutex_unlock(&clients_lock);
+
+	if (i < MAX_DIBS_CLIENTS) {
+		/* initialize with all devices that we got so far */
+		list_for_each_entry(dibs, &dibs_dev_list.list, list) {
+			dibs->priv[i] = NULL;
+			client->ops->add_dev(dibs);
+			dibs_setup_forwarding(client, dibs);
+		}
+	}
+	mutex_unlock(&dibs_dev_list.mutex);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(dibs_register_client);
+
+int dibs_unregister_client(struct dibs_client *client)
+{
+	struct dibs_dev *dibs;
+	unsigned long flags;
+	int max_dmbs;
+	int rc = 0;
+
+	mutex_lock(&dibs_dev_list.mutex);
+	list_for_each_entry(dibs, &dibs_dev_list.list, list) {
+		spin_lock_irqsave(&dibs->lock, flags);
+		max_dmbs = dibs->ops->max_dmbs();
+		for (int i = 0; i < max_dmbs; ++i) {
+			if (dibs->dmb_clientid_arr[i] == client->id) {
+				WARN(1, "%s: attempt to unregister '%s' with registered dmb(s)\n",
+				     __func__, client->name);
+				rc = -EBUSY;
+				goto err_reg_dmb;
+			}
+		}
+		/* Stop forwarding IRQs and events */
+		dibs->subs[client->id] = NULL;
+		spin_unlock_irqrestore(&dibs->lock, flags);
+		clients[client->id]->ops->del_dev(dibs);
+		dibs->priv[client->id] = NULL;
+	}
+
+	mutex_lock(&clients_lock);
+	clients[client->id] = NULL;
+	if (client->id + 1 == max_client)
+		max_client--;
+	mutex_unlock(&clients_lock);
+
+	mutex_unlock(&dibs_dev_list.mutex);
+	return rc;
+
+err_reg_dmb:
+	spin_unlock_irqrestore(&dibs->lock, flags);
+	mutex_unlock(&dibs_dev_list.mutex);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(dibs_unregister_client);
+
+static void dibs_dev_release(struct device *dev)
+{
+	struct dibs_dev *dibs;
+
+	dibs = container_of(dev, struct dibs_dev, dev);
+
+	kfree(dibs);
+}
+
+struct dibs_dev *dibs_dev_alloc(void)
+{
+	struct dibs_dev *dibs;
+
+	dibs = kzalloc(sizeof(*dibs), GFP_KERNEL);
+	if (!dibs)
+		return dibs;
+	dibs->dev.release = dibs_dev_release;
+	dibs->dev.class = dibs_class;
+	device_initialize(&dibs->dev);
+
+	return dibs;
+}
+EXPORT_SYMBOL_GPL(dibs_dev_alloc);
+
+static ssize_t gid_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct dibs_dev *dibs;
+
+	dibs = container_of(dev, struct dibs_dev, dev);
+
+	return sysfs_emit(buf, "%pUb\n", &dibs->gid);
+}
+static DEVICE_ATTR_RO(gid);
+
+static ssize_t fabric_id_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct dibs_dev *dibs;
+	u16 fabric_id;
+
+	dibs = container_of(dev, struct dibs_dev, dev);
+	fabric_id = dibs->ops->get_fabric_id(dibs);
+
+	return sysfs_emit(buf, "0x%04x\n", fabric_id);
+}
+static DEVICE_ATTR_RO(fabric_id);
+
+static struct attribute *dibs_dev_attrs[] = {
+	&dev_attr_gid.attr,
+	&dev_attr_fabric_id.attr,
+	NULL,
+};
+
+static const struct attribute_group dibs_dev_attr_group = {
+	.attrs = dibs_dev_attrs,
+};
+
+int dibs_dev_add(struct dibs_dev *dibs)
+{
+	int max_dmbs;
+	int i, ret;
+
+	max_dmbs = dibs->ops->max_dmbs();
+	spin_lock_init(&dibs->lock);
+	dibs->dmb_clientid_arr = kzalloc(max_dmbs, GFP_KERNEL);
+	if (!dibs->dmb_clientid_arr)
+		return -ENOMEM;
+	memset(dibs->dmb_clientid_arr, NO_DIBS_CLIENT, max_dmbs);
+
+	ret = device_add(&dibs->dev);
+	if (ret)
+		goto free_client_arr;
+
+	ret = sysfs_create_group(&dibs->dev.kobj, &dibs_dev_attr_group);
+	if (ret) {
+		dev_err(&dibs->dev, "sysfs_create_group failed for dibs_dev\n");
+		goto err_device_del;
+	}
+	mutex_lock(&dibs_dev_list.mutex);
+	mutex_lock(&clients_lock);
+	for (i = 0; i < max_client; ++i) {
+		if (clients[i]) {
+			clients[i]->ops->add_dev(dibs);
+			dibs_setup_forwarding(clients[i], dibs);
+		}
+	}
+	mutex_unlock(&clients_lock);
+	list_add(&dibs->list, &dibs_dev_list.list);
+	mutex_unlock(&dibs_dev_list.mutex);
+
+	return 0;
+
+err_device_del:
+	device_del(&dibs->dev);
+free_client_arr:
+	kfree(dibs->dmb_clientid_arr);
+	return ret;
+
+}
+EXPORT_SYMBOL_GPL(dibs_dev_add);
+
+void dibs_dev_del(struct dibs_dev *dibs)
+{
+	unsigned long flags;
+	int i;
+
+	sysfs_remove_group(&dibs->dev.kobj, &dibs_dev_attr_group);
+
+	spin_lock_irqsave(&dibs->lock, flags);
+	for (i = 0; i < MAX_DIBS_CLIENTS; ++i)
+		dibs->subs[i] = NULL;
+	spin_unlock_irqrestore(&dibs->lock, flags);
+
+	mutex_lock(&dibs_dev_list.mutex);
+	mutex_lock(&clients_lock);
+	for (i = 0; i < max_client; ++i) {
+		if (clients[i])
+			clients[i]->ops->del_dev(dibs);
+	}
+	mutex_unlock(&clients_lock);
+	list_del_init(&dibs->list);
+	mutex_unlock(&dibs_dev_list.mutex);
+
+	device_del(&dibs->dev);
+	kfree(dibs->dmb_clientid_arr);
+}
+EXPORT_SYMBOL_GPL(dibs_dev_del);
+
+static int __init dibs_init(void)
+{
+	int rc;
+
+	memset(clients, 0, sizeof(clients));
+	max_client = 0;
+
+	dibs_class = class_create("dibs");
+	if (IS_ERR(&dibs_class))
+		return PTR_ERR(&dibs_class);
+
+	rc = dibs_loopback_init();
+	if (rc)
+		pr_err("%s fails with %d\n", __func__, rc);
+
+	return rc;
+}
+
+static void __exit dibs_exit(void)
+{
+	dibs_loopback_exit();
+	class_destroy(dibs_class);
+}
+
+module_init(dibs_init);
+module_exit(dibs_exit);

drivers/s390/net/Kconfig

···
 
 config ISM
 	tristate "Support for ISM vPCI Adapter"
-	depends on PCI
-	imply SMC
+	depends on PCI && DIBS
 	default n
 	help
 	  Select this option if you want to use the Internal Shared Memory

drivers/s390/net/ism.h

···
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/pci.h>
-#include <linux/ism.h>
-#include <net/smc.h>
+#include <linux/dibs.h>
 #include <asm/pci_insn.h>
 
 #define UTIL_STR_LEN	16
+#define ISM_ERROR	0xFFFF
+
+#define ISM_NR_DMBS	1920
 
 /*
  * Do not use the first word of the DMB bits to ensure 8 byte aligned access.
···
 #define ISM_SIGNAL_IEQ	0xE
 #define ISM_UNREG_SBA	0x11
 #define ISM_UNREG_IEQ	0x12
+
+enum ism_event_type {
+	ISM_EVENT_BUF = 0x00,
+	ISM_EVENT_DEV = 0x01,
+	ISM_EVENT_SWR = 0x02
+};
+
+enum ism_event_code {
+	ISM_BUF_DMB_UNREGISTERED = 0x04,
+	ISM_BUF_USING_ISM_DEV_DISABLED = 0x08,
+	ISM_BUF_OWNING_ISM_DEV_IN_ERR_STATE = 0x02,
+	ISM_BUF_USING_ISM_DEV_IN_ERR_STATE = 0x03,
+	ISM_BUF_VLAN_MISMATCH_WITH_OWNER = 0x05,
+	ISM_BUF_VLAN_MISMATCH_WITH_USER = 0x06,
+	ISM_DEV_GID_DISABLED = 0x07,
+	ISM_DEV_GID_ERR_STATE = 0x01
+};
 
 struct ism_req_hdr {
 	u32 cmd;
···
 	} response;
 } __aligned(16);
 
+/* ISM-vPCI devices provide 64 Bit GIDs
+ * Map them to ISM UUID GIDs like this:
+ *  _________________________________________
+ * | 64 Bit ISM-vPCI GID | 00000000_00000000 |
+ *  -----------------------------------------
+ * This will be interpreted as a UIID variant, that is reserved
+ * for NCS backward compatibility. So it will not collide with
+ * proper UUIDs.
+ */
 union ism_read_gid {
 	struct {
 		struct ism_req_hdr hdr;
···
 	u64 : 64;
 };
 
+struct ism_event {
+	u32 type;
+	u32 code;
+	u64 tok;
+	u64 time;
+	u64 info;
+};
+
 struct ism_eq {
 	struct ism_eq_header header;
 	struct ism_event entry[15];
···
 	u32 dmb_bits[ISM_NR_DMBS / 32];
 	u32 reserved[3];
 	u16 dmbe_mask[ISM_NR_DMBS];
+};
+
+struct ism_dev {
+	spinlock_t cmd_lock; /* serializes cmds */
+	struct dibs_dev *dibs;
+	struct pci_dev *pdev;
+	struct ism_sba *sba;
+	dma_addr_t sba_dma_addr;
+	DECLARE_BITMAP(sba_bitmap, ISM_NR_DMBS);
+
+	struct ism_eq *ieq;
+	dma_addr_t ieq_dma_addr;
+	int ieq_idx;
 };
 
 #define ISM_CREATE_REQ(dmb, idx, sf, offset)		\

drivers/s390/net/ism_drv.c

···
 
 static debug_info_t *ism_debug_info;
 
-#define NO_CLIENT		0xff		/* must be >= MAX_CLIENTS */
-static struct ism_client *clients[MAX_CLIENTS];	/* use an array rather than */
-						/* a list for fast mapping  */
-static u8 max_client;
-static DEFINE_MUTEX(clients_lock);
-static bool ism_v2_capable;
-struct ism_dev_list {
-	struct list_head list;
-	struct mutex mutex; /* protects ism device list */
-};
-
-static struct ism_dev_list ism_dev_list = {
-	.list = LIST_HEAD_INIT(ism_dev_list.list),
-	.mutex = __MUTEX_INITIALIZER(ism_dev_list.mutex),
-};
-
-static void ism_setup_forwarding(struct ism_client *client, struct ism_dev *ism)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&ism->lock, flags);
-	ism->subs[client->id] = client;
-	spin_unlock_irqrestore(&ism->lock, flags);
-}
-
-int ism_register_client(struct ism_client *client)
-{
-	struct ism_dev *ism;
-	int i, rc = -ENOSPC;
-
-	mutex_lock(&ism_dev_list.mutex);
-	mutex_lock(&clients_lock);
-	for (i = 0; i < MAX_CLIENTS; ++i) {
-		if (!clients[i]) {
-			clients[i] = client;
-			client->id = i;
-			if (i == max_client)
-				max_client++;
-			rc = 0;
-			break;
-		}
-	}
-	mutex_unlock(&clients_lock);
-
-	if (i < MAX_CLIENTS) {
-		/* initialize with all devices that we got so far */
-		list_for_each_entry(ism, &ism_dev_list.list, list) {
-			ism->priv[i] = NULL;
-			client->add(ism);
-			ism_setup_forwarding(client, ism);
-		}
-	}
-	mutex_unlock(&ism_dev_list.mutex);
-
-	return rc;
-}
-EXPORT_SYMBOL_GPL(ism_register_client);
-
-int ism_unregister_client(struct ism_client *client)
-{
-	struct ism_dev *ism;
-	unsigned long flags;
-	int rc = 0;
-
-	mutex_lock(&ism_dev_list.mutex);
-	list_for_each_entry(ism, &ism_dev_list.list, list) {
-		spin_lock_irqsave(&ism->lock, flags);
-		/* Stop forwarding IRQs and events */
-		ism->subs[client->id] = NULL;
-		for (int i = 0; i < ISM_NR_DMBS; ++i) {
-			if (ism->sba_client_arr[i] == client->id) {
-				WARN(1, "%s: attempt to unregister '%s' with registered dmb(s)\n",
-				     __func__, client->name);
-				rc = -EBUSY;
-				goto err_reg_dmb;
-			}
-		}
-		spin_unlock_irqrestore(&ism->lock, flags);
-	}
-	mutex_unlock(&ism_dev_list.mutex);
-
-	mutex_lock(&clients_lock);
-	clients[client->id] = NULL;
-	if (client->id + 1 == max_client)
-		max_client--;
-	mutex_unlock(&clients_lock);
-	return rc;
-
-err_reg_dmb:
-	spin_unlock_irqrestore(&ism->lock, flags);
-	mutex_unlock(&ism_dev_list.mutex);
-	return rc;
-}
-EXPORT_SYMBOL_GPL(ism_unregister_client);
-
 static int ism_cmd(struct ism_dev *ism, void *cmd)
 {
 	struct ism_req_hdr *req = cmd;
···
 	return 0;
 }
 
-static int ism_read_local_gid(struct ism_dev *ism)
+static int ism_read_local_gid(struct dibs_dev *dibs)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	union ism_read_gid cmd;
 	int ret;
 
···
 	if (ret)
 		goto out;
 
-	ism->local_gid = cmd.response.gid;
+	memset(&dibs->gid, 0, sizeof(dibs->gid));
+	memcpy(&dibs->gid, &cmd.response.gid, sizeof(cmd.response.gid));
 out:
 	return ret;
 }
 
-static void ism_free_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
+static int ism_query_rgid(struct dibs_dev *dibs, const uuid_t *rgid,
+			  u32 vid_valid, u32 vid)
 {
-	clear_bit(dmb->sba_idx, ism->sba_bitmap);
+	struct ism_dev *ism = dibs->drv_priv;
+	union ism_query_rgid cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.request.hdr.cmd = ISM_QUERY_RGID;
+	cmd.request.hdr.len = sizeof(cmd.request);
+
+	memcpy(&cmd.request.rgid, rgid, sizeof(cmd.request.rgid));
+	cmd.request.vlan_valid = vid_valid;
+	cmd.request.vlan_id = vid;
+
+	return ism_cmd(ism, &cmd);
+}
+
+static int ism_max_dmbs(void)
+{
+	return ISM_NR_DMBS;
+}
+
+static void ism_free_dmb(struct ism_dev *ism, struct dibs_dmb *dmb)
+{
+	clear_bit(dmb->idx, ism->sba_bitmap);
 	dma_unmap_page(&ism->pdev->dev, dmb->dma_addr, dmb->dmb_len,
 		       DMA_FROM_DEVICE);
 	folio_put(virt_to_folio(dmb->cpu_addr));
 }
 
-static int ism_alloc_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
+static int ism_alloc_dmb(struct ism_dev *ism, struct dibs_dmb *dmb)
 {
 	struct folio *folio;
 	unsigned long bit;
···
 	if (PAGE_ALIGN(dmb->dmb_len) > dma_get_max_seg_size(&ism->pdev->dev))
 		return -EINVAL;
 
-	if (!dmb->sba_idx) {
+	if (!dmb->idx) {
 		bit = find_next_zero_bit(ism->sba_bitmap, ISM_NR_DMBS,
 					 ISM_DMB_BIT_OFFSET);
 		if (bit == ISM_NR_DMBS)
 			return -ENOSPC;
 
-		dmb->sba_idx = bit;
+		dmb->idx = bit;
 	}
-	if (dmb->sba_idx < ISM_DMB_BIT_OFFSET ||
-	    test_and_set_bit(dmb->sba_idx, ism->sba_bitmap))
+	if (dmb->idx < ISM_DMB_BIT_OFFSET ||
+	    test_and_set_bit(dmb->idx, ism->sba_bitmap))
 		return -EINVAL;
 
 	folio = folio_alloc(GFP_KERNEL | __GFP_NOWARN | __GFP_NOMEMALLOC |
···
 out_free:
 	kfree(dmb->cpu_addr);
 out_bit:
-	clear_bit(dmb->sba_idx, ism->sba_bitmap);
+	clear_bit(dmb->idx, ism->sba_bitmap);
 	return rc;
 }
 
-int ism_register_dmb(struct ism_dev *ism, struct ism_dmb *dmb,
-		     struct ism_client *client)
+static int ism_register_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb,
+			    struct dibs_client *client)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	union ism_reg_dmb cmd;
 	unsigned long flags;
 	int ret;
···
 
 	cmd.request.dmb = dmb->dma_addr;
 	cmd.request.dmb_len = dmb->dmb_len;
-	cmd.request.sba_idx = dmb->sba_idx;
+	cmd.request.sba_idx = dmb->idx;
 	cmd.request.vlan_valid = dmb->vlan_valid;
 	cmd.request.vlan_id = dmb->vlan_id;
-	cmd.request.rgid = dmb->rgid;
+	memcpy(&cmd.request.rgid, &dmb->rgid, sizeof(u64));
 
 	ret = ism_cmd(ism, &cmd);
 	if (ret) {
···
 		goto out;
 	}
 	dmb->dmb_tok = cmd.response.dmb_tok;
-	spin_lock_irqsave(&ism->lock, flags);
-	ism->sba_client_arr[dmb->sba_idx - ISM_DMB_BIT_OFFSET] = client->id;
-	spin_unlock_irqrestore(&ism->lock, flags);
+	spin_lock_irqsave(&dibs->lock, flags);
+	dibs->dmb_clientid_arr[dmb->idx - ISM_DMB_BIT_OFFSET] = client->id;
+	spin_unlock_irqrestore(&dibs->lock, flags);
 out:
 	return ret;
 }
-EXPORT_SYMBOL_GPL(ism_register_dmb);
 
-int ism_unregister_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
+static int ism_unregister_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	union ism_unreg_dmb cmd;
 	unsigned long flags;
 	int ret;
···
 
 	cmd.request.dmb_tok = dmb->dmb_tok;
 
-	spin_lock_irqsave(&ism->lock, flags);
-	ism->sba_client_arr[dmb->sba_idx - ISM_DMB_BIT_OFFSET] = NO_CLIENT;
-	spin_unlock_irqrestore(&ism->lock, flags);
+	spin_lock_irqsave(&dibs->lock, flags);
+	dibs->dmb_clientid_arr[dmb->idx - ISM_DMB_BIT_OFFSET] = NO_DIBS_CLIENT;
+	spin_unlock_irqrestore(&dibs->lock, flags);
 
 	ret = ism_cmd(ism, &cmd);
 	if (ret && ret != ISM_ERROR)
···
 out:
 	return ret;
 }
-EXPORT_SYMBOL_GPL(ism_unregister_dmb);
 
-static int ism_add_vlan_id(struct ism_dev *ism, u64 vlan_id)
+static int ism_add_vlan_id(struct dibs_dev *dibs, u64 vlan_id)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	union ism_set_vlan_id cmd;
 
 	memset(&cmd, 0, sizeof(cmd));
···
 	return ism_cmd(ism, &cmd);
 }
 
-static int ism_del_vlan_id(struct ism_dev *ism, u64 vlan_id)
+static int ism_del_vlan_id(struct dibs_dev *dibs, u64 vlan_id)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	union ism_set_vlan_id cmd;
 
 	memset(&cmd, 0, sizeof(cmd));
···
 	return ism_cmd(ism, &cmd);
 }
 
+static int ism_signal_ieq(struct dibs_dev *dibs, const uuid_t *rgid,
+			  u32 trigger_irq, u32 event_code, u64 info)
+{
+	struct ism_dev *ism = dibs->drv_priv;
+	union ism_sig_ieq cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.request.hdr.cmd = ISM_SIGNAL_IEQ;
+	cmd.request.hdr.len = sizeof(cmd.request);
+
+	memcpy(&cmd.request.rgid, rgid, sizeof(cmd.request.rgid));
+	cmd.request.trigger_irq = trigger_irq;
+	cmd.request.event_code = event_code;
+	cmd.request.info = info;
+
+	return ism_cmd(ism, &cmd);
+}
+
 static unsigned int max_bytes(unsigned int start, unsigned int len,
 			      unsigned int boundary)
 {
 	return min(boundary - (start & (boundary - 1)), len);
 }
 
-int ism_move(struct ism_dev *ism, u64 dmb_tok, unsigned int idx, bool sf,
-	     unsigned int offset, void *data, unsigned int size)
+static int ism_move(struct dibs_dev *dibs, u64 dmb_tok, unsigned int idx,
+		    bool sf, unsigned int offset, void *data,
+		    unsigned int size)
 {
+	struct ism_dev *ism = dibs->drv_priv;
 	unsigned int bytes;
 	u64 dmb_req;
 	int ret;
···
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(ism_move);
+
+static u16 ism_get_chid(struct dibs_dev *dibs)
+{
+	struct ism_dev *ism = dibs->drv_priv;
+
+	if (!ism || !ism->pdev)
+		return 0;
+
+	return to_zpci(ism->pdev)->pchid;
+}
+
+static int ism_match_event_type(u32 s390_event_type)
+{
+	switch (s390_event_type) {
+	case ISM_EVENT_BUF:
+		return DIBS_BUF_EVENT;
+	case ISM_EVENT_DEV:
+		return DIBS_DEV_EVENT;
+	case ISM_EVENT_SWR:
+		return DIBS_SW_EVENT;
+	default:
+		return DIBS_OTHER_TYPE;
+	}
+}
+
+static int ism_match_event_subtype(u32 s390_event_subtype)
+{
+	switch (s390_event_subtype) {
+	case ISM_BUF_DMB_UNREGISTERED:
+		return DIBS_BUF_UNREGISTERED;
+	case ISM_DEV_GID_DISABLED:
+		return DIBS_DEV_DISABLED;
+	case ISM_DEV_GID_ERR_STATE:
+		return DIBS_DEV_ERR_STATE;
+	default:
+		return DIBS_OTHER_SUBTYPE;
+	}
+}
 
 static void ism_handle_event(struct ism_dev *ism)
 {
+	struct dibs_dev *dibs = ism->dibs;
+	struct dibs_event event;
 	struct ism_event *entry;
-	struct ism_client *clt;
+	struct dibs_client *clt;
 	int i;
 
 	while ((ism->ieq_idx + 1) != READ_ONCE(ism->ieq->header.idx)) {
-		if (++(ism->ieq_idx) == ARRAY_SIZE(ism->ieq->entry))
+		if (++ism->ieq_idx == ARRAY_SIZE(ism->ieq->entry))
 			ism->ieq_idx = 0;
 
 		entry = &ism->ieq->entry[ism->ieq_idx];
 		debug_event(ism_debug_info, 2, entry, sizeof(*entry));
-		for (i = 0; i < max_client; ++i) {
-			clt = ism->subs[i];
+		__memset(&event, 0, sizeof(event));
+		event.type = ism_match_event_type(entry->type);
+		if (event.type == DIBS_SW_EVENT)
+			event.subtype = entry->code;
+		else
+			event.subtype = ism_match_event_subtype(entry->code);
+		event.time = entry->time;
+		event.data = entry->info;
+		switch (event.type) {
+		case DIBS_BUF_EVENT:
+			event.buffer_tok = entry->tok;
+			break;
+		case DIBS_DEV_EVENT:
+		case DIBS_SW_EVENT:
+			memcpy(&event.gid, &entry->tok, sizeof(u64));
+		}
+		for (i = 0; i < MAX_DIBS_CLIENTS; ++i) {
+			clt = dibs->subs[i];
 			if (clt)
-				clt->handle_event(ism, entry);
+				clt->ops->handle_event(dibs, &event);
 		}
 	}
 }
···
 {
 	struct ism_dev *ism = data;
 	unsigned long bit, end;
+	struct dibs_dev *dibs;
 	unsigned long *bv;
 	u16 dmbemask;
 	u8 client_id;
 
+	dibs = ism->dibs;
+
 	bv = (void *) &ism->sba->dmb_bits[ISM_DMB_WORD_OFFSET];
 	end = sizeof(ism->sba->dmb_bits) * BITS_PER_BYTE - ISM_DMB_BIT_OFFSET;
 
-	spin_lock(&ism->lock);
+	spin_lock(&dibs->lock);
 	ism->sba->s = 0;
 	barrier();
 	for (bit = 0;;) {
···
 		dmbemask = ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET];
 		ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0;
 		barrier();
-		client_id = ism->sba_client_arr[bit];
-		if (unlikely(client_id == NO_CLIENT || !ism->subs[client_id]))
+		client_id = dibs->dmb_clientid_arr[bit];
+		if (unlikely(client_id == NO_DIBS_CLIENT ||
+			     !dibs->subs[client_id]))
 			continue;
-		ism->subs[client_id]->handle_irq(ism, bit + ISM_DMB_BIT_OFFSET, dmbemask);
+		dibs->subs[client_id]->ops->handle_irq(dibs,
+						       bit + ISM_DMB_BIT_OFFSET,
+						       dmbemask);
 	}
 
 	if (ism->sba->e) {
···
 		barrier();
 		ism_handle_event(ism);
 	}
-	spin_unlock(&ism->lock);
+	spin_unlock(&dibs->lock);
 	return IRQ_HANDLED;
 }
+
+static const struct dibs_dev_ops ism_ops = {
+	.get_fabric_id = ism_get_chid,
+	.query_remote_gid = ism_query_rgid,
+	.max_dmbs = ism_max_dmbs,
+	.register_dmb = ism_register_dmb,
+	.unregister_dmb = ism_unregister_dmb,
+	.move_data = ism_move,
+	.add_vlan_id = ism_add_vlan_id,
+	.del_vlan_id = ism_del_vlan_id,
+	.signal_event = ism_signal_ieq,
+};
 
 static int ism_dev_init(struct ism_dev *ism)
 {
 	struct pci_dev *pdev = ism->pdev;
-	int i, ret;
+	int ret;
 
 	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
 	if (ret <= 0)
 		goto out;
 
-	ism->sba_client_arr = kzalloc(ISM_NR_DMBS, GFP_KERNEL);
-	if (!ism->sba_client_arr)
-		goto free_vectors;
-	memset(ism->sba_client_arr, NO_CLIENT, ISM_NR_DMBS);
-
 	ret = request_irq(pci_irq_vector(pdev, 0), ism_handle_irq, 0,
 			  pci_name(pdev), ism);
 	if (ret)
-		goto free_client_arr;
+		goto free_vectors;
 
 	ret = register_sba(ism);
 	if (ret)
···
 	if (ret)
 		goto unreg_sba;
 
-	ret = ism_read_local_gid(ism);
-	if (ret)
-		goto unreg_ieq;
-
-	if (!ism_add_vlan_id(ism, ISM_RESERVED_VLANID))
-		/* hardware is V2 capable */
-		ism_v2_capable = true;
-	else
-		ism_v2_capable = false;
-
-	mutex_lock(&ism_dev_list.mutex);
-	mutex_lock(&clients_lock);
-	for (i = 0; i < max_client; ++i) {
-		if (clients[i]) {
-			clients[i]->add(ism);
-			ism_setup_forwarding(clients[i], ism);
-		}
-	}
-	mutex_unlock(&clients_lock);
-
-	list_add(&ism->list, &ism_dev_list.list);
-	mutex_unlock(&ism_dev_list.mutex);
-
 	query_info(ism);
 	return 0;
 
-unreg_ieq:
-	unregister_ieq(ism);
 unreg_sba:
 	unregister_sba(ism);
 free_irq:
 	free_irq(pci_irq_vector(pdev, 0), ism);
-free_client_arr:
-	kfree(ism->sba_client_arr);
 free_vectors:
 	pci_free_irq_vectors(pdev);
 out:
 	return ret;
 }
 
-static void ism_dev_release(struct device *dev)
+static void ism_dev_exit(struct ism_dev *ism)
 {
-	struct ism_dev *ism;
+	struct pci_dev *pdev = ism->pdev;
 
-	ism = container_of(dev, struct ism_dev, dev);
-
-	kfree(ism);
+	unregister_ieq(ism);
+	unregister_sba(ism);
+	free_irq(pci_irq_vector(pdev, 0), ism);
+	pci_free_irq_vectors(pdev);
 }
 
 static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
+	struct dibs_dev *dibs;
+	struct zpci_dev *zdev;
 	struct ism_dev *ism;
 	int ret;
 
···
 	if (!ism)
 		return -ENOMEM;
 
-	spin_lock_init(&ism->lock);
 	spin_lock_init(&ism->cmd_lock);
 	dev_set_drvdata(&pdev->dev, ism);
 	ism->pdev = pdev;
-	ism->dev.parent = &pdev->dev;
-	ism->dev.release = ism_dev_release;
-	device_initialize(&ism->dev);
-	dev_set_name(&ism->dev, "%s", dev_name(&pdev->dev));
-	ret = device_add(&ism->dev);
-	if (ret)
-		goto err_dev;
 
 	ret = pci_enable_device_mem(pdev);
 	if (ret)
-		goto err;
+		goto err_dev;
 
 	ret = pci_request_mem_regions(pdev, DRV_NAME);
 	if (ret)
···
 	dma_set_max_seg_size(&pdev->dev, SZ_1M);
 	pci_set_master(pdev);
 
+	dibs = dibs_dev_alloc();
+	if (!dibs) {
+		ret = -ENOMEM;
+		goto err_resource;
+	}
+	/* set this up before we enable interrupts */
+	ism->dibs = dibs;
+	dibs->drv_priv = ism;
+	dibs->ops = &ism_ops;
+
+	/* enable ism device, but any interrupts and events will be ignored
+	 * before dibs_dev_add() adds it to any clients.
+	 */
 	ret = ism_dev_init(ism);
 	if (ret)
-		goto err_resource;
+		goto err_dibs;
+
+	/* after ism_dev_init() we can call ism function to set gid */
+	ret = ism_read_local_gid(dibs);
+	if (ret)
+		goto err_ism;
+
+	dibs->dev.parent = &pdev->dev;
+
+	zdev = to_zpci(pdev);
+	dev_set_name(&dibs->dev, "ism%x", zdev->uid ? zdev->uid : zdev->fid);
+
+	ret = dibs_dev_add(dibs);
+	if (ret)
+		goto err_ism;
 
 	return 0;
 
+err_ism:
+	ism_dev_exit(ism);
+err_dibs:
+	/* pairs with dibs_dev_alloc() */
+	put_device(&dibs->dev);
 err_resource:
 	pci_release_mem_regions(pdev);
 err_disable:
 	pci_disable_device(pdev);
-err:
-	device_del(&ism->dev);
 err_dev:
 	dev_set_drvdata(&pdev->dev, NULL);
-	put_device(&ism->dev);
+	kfree(ism);
 
 	return ret;
-}
-
-static void ism_dev_exit(struct ism_dev *ism)
-{
-	struct pci_dev *pdev = ism->pdev;
-	unsigned long flags;
-	int i;
-
-	spin_lock_irqsave(&ism->lock, flags);
-	for (i = 0; i < max_client; ++i)
-		ism->subs[i] = NULL;
-	spin_unlock_irqrestore(&ism->lock, flags);
-
-	mutex_lock(&ism_dev_list.mutex);
-	mutex_lock(&clients_lock);
-	for (i = 0; i < max_client; ++i) {
-		if (clients[i])
-			clients[i]->remove(ism);
-	}
-	mutex_unlock(&clients_lock);
-
-	if (ism_v2_capable)
-		ism_del_vlan_id(ism, ISM_RESERVED_VLANID);
-	unregister_ieq(ism);
-	unregister_sba(ism);
-	free_irq(pci_irq_vector(pdev, 0), ism);
-	kfree(ism->sba_client_arr);
-	pci_free_irq_vectors(pdev);
-	list_del_init(&ism->list);
-	mutex_unlock(&ism_dev_list.mutex);
 }
 
 static void ism_remove(struct pci_dev *pdev)
 {
 	struct ism_dev *ism = dev_get_drvdata(&pdev->dev);
+	struct dibs_dev *dibs = ism->dibs;
 
+	dibs_dev_del(dibs);
 	ism_dev_exit(ism);
+	/* pairs with dibs_dev_alloc() */
+	put_device(&dibs->dev);
 
 	pci_release_mem_regions(pdev);
 	pci_disable_device(pdev);
-	device_del(&ism->dev);
 	dev_set_drvdata(&pdev->dev, NULL);
-	put_device(&ism->dev);
+	kfree(ism);
 }
 
 static struct pci_driver ism_driver = {
···
 	if (!ism_debug_info)
 		return -ENODEV;
 
-	memset(clients, 0, sizeof(clients));
-	max_client = 0;
 	debug_register_view(ism_debug_info, &debug_hex_ascii_view);
 	ret = pci_register_driver(&ism_driver);
 	if (ret)
···
 
 module_init(ism_init);
 module_exit(ism_exit);
-
-/*************************** SMC-D Implementation *****************************/
-
-#if IS_ENABLED(CONFIG_SMC)
-static int ism_query_rgid(struct ism_dev *ism, u64 rgid, u32 vid_valid,
-			  u32 vid)
-{
-	union ism_query_rgid cmd;
-
-	memset(&cmd, 0, sizeof(cmd));
-	cmd.request.hdr.cmd = ISM_QUERY_RGID;
-	cmd.request.hdr.len = sizeof(cmd.request);
-
-	cmd.request.rgid = rgid;
-	cmd.request.vlan_valid = vid_valid;
-	cmd.request.vlan_id = vid;
-
-	return ism_cmd(ism, &cmd);
-}
-
-static int smcd_query_rgid(struct smcd_dev *smcd, struct smcd_gid *rgid,
-			   u32 vid_valid, u32 vid)
-{
-	return ism_query_rgid(smcd->priv, rgid->gid, vid_valid, vid);
-}
-
-static int smcd_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
-			     void *client)
-{
-	return ism_register_dmb(smcd->priv, (struct ism_dmb *)dmb, client);
-}
-
-static int smcd_unregister_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
-{
-	return ism_unregister_dmb(smcd->priv, (struct ism_dmb *)dmb);
-}
-
-static int smcd_add_vlan_id(struct smcd_dev *smcd, u64 vlan_id)
-{
-	return ism_add_vlan_id(smcd->priv, vlan_id);
-}
-
-static int smcd_del_vlan_id(struct smcd_dev *smcd, u64 vlan_id)
-{
-	return ism_del_vlan_id(smcd->priv, vlan_id);
-}
-
-static int smcd_set_vlan_required(struct smcd_dev *smcd)
-{
-	return ism_cmd_simple(smcd->priv, ISM_SET_VLAN);
-}
-
-static int smcd_reset_vlan_required(struct smcd_dev *smcd)
-{
-	return ism_cmd_simple(smcd->priv, ISM_RESET_VLAN);
-}
-
-static int ism_signal_ieq(struct ism_dev *ism, u64 rgid, u32 trigger_irq,
-			  u32 event_code, u64 info)
-{
-	union ism_sig_ieq cmd;
-
-	memset(&cmd, 0, sizeof(cmd));
-	cmd.request.hdr.cmd = ISM_SIGNAL_IEQ;
-	cmd.request.hdr.len = sizeof(cmd.request);
-
-	cmd.request.rgid = rgid;
-	cmd.request.trigger_irq = trigger_irq;
-	cmd.request.event_code = event_code;
-	cmd.request.info = info;
-
-	return ism_cmd(ism, &cmd);
-}
-
-static int smcd_signal_ieq(struct smcd_dev *smcd, struct smcd_gid *rgid,
-			   u32 trigger_irq, u32 event_code, u64 info)
-{
-	return ism_signal_ieq(smcd->priv, rgid->gid,
-			      trigger_irq, event_code, info);
-}
-
-static int smcd_move(struct smcd_dev *smcd, u64 dmb_tok, unsigned int idx,
-		     bool sf, unsigned int offset, void *data,
-		     unsigned int size)
-{
-	return ism_move(smcd->priv, dmb_tok, idx, sf, offset, data, size);
-}
-
-static int smcd_supports_v2(void)
-{
-	return ism_v2_capable;
-}
-
-static u64 ism_get_local_gid(struct ism_dev *ism)
-{
-	return ism->local_gid;
-}
-
-static void smcd_get_local_gid(struct smcd_dev *smcd,
-			       struct smcd_gid *smcd_gid)
-{
-	smcd_gid->gid = ism_get_local_gid(smcd->priv);
-	smcd_gid->gid_ext = 0;
-}
-
-static u16 ism_get_chid(struct ism_dev *ism)
-{
-	if (!ism || !ism->pdev)
-		return 0;
-
-	return to_zpci(ism->pdev)->pchid;
-}
-
-static u16 smcd_get_chid(struct smcd_dev *smcd)
-{
-	return ism_get_chid(smcd->priv);
-}
-
-static inline struct device *smcd_get_dev(struct smcd_dev *dev)
-{
-	struct ism_dev *ism = dev->priv;
-
-	return &ism->dev;
-}
-
-static const struct smcd_ops ism_ops = {
-	.query_remote_gid = smcd_query_rgid,
-	.register_dmb = smcd_register_dmb,
-	.unregister_dmb = smcd_unregister_dmb,
-	.add_vlan_id = smcd_add_vlan_id,
-	.del_vlan_id = smcd_del_vlan_id,
-	.set_vlan_required = smcd_set_vlan_required,
-	.reset_vlan_required = smcd_reset_vlan_required,
-	.signal_event = smcd_signal_ieq,
-	.move_data = smcd_move,
-	.supports_v2 = smcd_supports_v2,
-	.get_local_gid = smcd_get_local_gid,
-	.get_chid = smcd_get_chid,
-	.get_dev = smcd_get_dev,
-};
-
-const struct smcd_ops *ism_get_smcd_ops(void)
-{
-	return &ism_ops;
-}
-EXPORT_SYMBOL_GPL(ism_get_smcd_ops);
-#endif

include/linux/dibs.h

···
+/* 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
+
+#include <linux/device.h>
+#include <linux/uuid.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.
+ */
+
+/* DMB - Direct Memory Buffer
+ * --------------------------
+ * A dibs client provides a dmb as input buffer for a local receiving
+ * dibs device for exactly one (remote) sending dibs device. Only this
+ * sending device can send data into this dmb using move_data(). Sender
+ * and receiver can be the same device. A dmb belongs to exactly one client.
+ */
+struct dibs_dmb {
+	/* tok - Token for this dmb
+	 * Used by remote and local devices and clients to address this dmb.
+	 * Provided by dibs fabric. Unique per dibs fabric.
+	 */
+	u64 dmb_tok;
+	/* rgid - GID of designated remote sending device */
+	uuid_t rgid;
+	/* cpu_addr - buffer address */
+	void *cpu_addr;
+	/* len - buffer length */
+	u32 dmb_len;
+	/* idx - Index of this DMB on this receiving device */
+	u32 idx;
+	/* VLAN support (deprecated)
+	 * In order to write into a vlan-tagged dmb, the remote device needs
+	 * to belong to the this vlan
+	 */
+	u32 vlan_valid;
+	u32 vlan_id;
+	/* optional, used by device driver */
+	dma_addr_t dma_addr;
+};
+
+/* DIBS events
+ * -----------
+ * Dibs devices can optionally notify dibs clients about events that happened
+ * in the fabric or at the remote device or remote dmb.
+ */
+enum dibs_event_type {
+	/* Buffer event, e.g. a remote dmb was unregistered */
+	DIBS_BUF_EVENT,
+	/* Device event, e.g. a remote dibs device was disabled */
+	DIBS_DEV_EVENT,
+	/* Software event, a dibs client can send an event signal to a
+	 * remote dibs device.
+	 */
+	DIBS_SW_EVENT,
+	DIBS_OTHER_TYPE };
+
+enum dibs_event_subtype {
+	DIBS_BUF_UNREGISTERED,
+	DIBS_DEV_DISABLED,
+	DIBS_DEV_ERR_STATE,
+	DIBS_OTHER_SUBTYPE
+};
+
+struct dibs_event {
+	u32 type;
+	u32 subtype;
+	/* uuid_null if invalid */
+	uuid_t gid;
+	/* zero if invalid */
+	u64 buffer_tok;
+	u64 time;
+	/* additional data or zero */
+	u64 data;
+};
+
+struct dibs_dev;
+
+/* DIBS client
+ * -----------
+ */
+#define MAX_DIBS_CLIENTS	8
+#define NO_DIBS_CLIENT		0xff
+/* All dibs clients have access to all dibs devices.
+ * A dibs client provides the following functions to be called by dibs layer or
+ * dibs device drivers:
+ */
+struct dibs_client_ops {
+	/**
+	 *  add_dev() - add a dibs device
+	 *  @dev: device that was added
+	 *
+	 * Will be called during dibs_register_client() for all existing
+	 * dibs devices and whenever a new dibs device is registered.
+	 * dev is usable until dibs_client.remove() is called.
+	 * *dev is protected by device refcounting.
+	 */
+	void (*add_dev)(struct dibs_dev *dev);
+	/**
+	 * del_dev() - remove a dibs device
+	 * @dev: device to be removed
+	 *
+	 * Will be called whenever a dibs device is removed.
+	 * Will be called during dibs_unregister_client() for all existing
+	 * dibs devices and whenever a dibs device is unregistered.
+	 * The device has already stopped initiative for this client:
+	 * No new handlers will be started.
+	 * The device is no longer usable by this client after this call.
+	 */
+	void (*del_dev)(struct dibs_dev *dev);
+	/**
+	 * handle_irq() - Handle signaling for a DMB
+	 * @dev: device that owns the dmb
+	 * @idx: Index of the dmb that got signalled
+	 * @dmbemask: signaling mask of the dmb
+	 *
+	 * Handle signaling for a dmb that was registered by this client
+	 * for this device.
+	 * The dibs device can coalesce multiple signaling triggers into a
+	 * single call of handle_irq(). dmbemask can be used to indicate
+	 * different kinds of triggers.
+	 *
+	 * Context: Called in IRQ context by dibs device driver
+	 */
+	void (*handle_irq)(struct dibs_dev *dev, unsigned int idx,
+			   u16 dmbemask);
+	/**
+	 * handle_event() - Handle control information sent by device
+	 * @dev: device reporting the event
+	 * @event: ism event structure
+	 *
+	 * * Context: Called in IRQ context by dibs device driver
+	 */
+	void (*handle_event)(struct dibs_dev *dev,
+			     const struct dibs_event *event);
+};
+
+struct dibs_client {
+	/* client name for logging and debugging purposes */
+	const char *name;
+	const struct dibs_client_ops *ops;
+	/* client index - provided and used by dibs layer */
+	u8 id;
+};
+
+/* Functions to be called by dibs clients:
+ */
+/**
+ * dibs_register_client() - register a client with dibs layer
+ * @client: this client
+ *
+ * Will call client->ops->add_dev() for all existing dibs devices.
+ * Return: zero on success.
+ */
+int dibs_register_client(struct dibs_client *client);
+/**
+ * dibs_unregister_client() - unregister a client with dibs layer
+ * @client: this client
+ *
+ * Will call client->ops->del_dev() for all existing dibs devices.
+ * Return: zero on success.
+ */
+int dibs_unregister_client(struct dibs_client *client);
+
+/* dibs clients can call dibs device ops. */
+
+/* DIBS devices
+ * ------------
+ */
+
+/* Defined fabric id / CHID for all loopback devices:
+ * All dibs loopback devices report this fabric id. In this case devices with
+ * the same fabric id can NOT communicate via dibs. Only loopback devices with
+ * the same dibs device gid can communicate (=same device with itself).
+ */
+#define DIBS_LOOPBACK_FABRIC	0xFFFF
+
+/* A dibs device provides the following functions to be called by dibs clients.
+ * They are mandatory, unless marked 'optional'.
+ */
+struct dibs_dev_ops {
+	/**
+	 * get_fabric_id()
+	 * @dev: local dibs device
+	 *
+	 * Only devices on the same dibs fabric can communicate. Fabric_id is
+	 * unique inside the same HW system. Use fabric_id for fast negative
+	 * checks, but only query_remote_gid() can give a reliable positive
+	 * answer:
+	 * Different fabric_id: dibs is not possible
+	 * Same fabric_id: dibs may be possible or not
+	 *		   (e.g. different HW systems)
+	 * EXCEPTION: DIBS_LOOPBACK_FABRIC denotes an ism_loopback device
+	 *	      that can only communicate with itself. Use dibs_dev.gid
+	 *	      or query_remote_gid()to determine whether sender and
+	 *	      receiver use the same ism_loopback device.
+	 * Return: 2 byte dibs fabric id
+	 */
+	u16 (*get_fabric_id)(struct dibs_dev *dev);
+	/**
+	 * query_remote_gid()
+	 * @dev: local dibs device
+	 * @rgid: gid of remote dibs device
+	 * @vid_valid: if zero, vid will be ignored;
+	 *	       deprecated, ignored if device does not support vlan
+	 * @vid: VLAN id; deprecated, ignored if device does not support vlan
+	 *
+	 * Query whether a remote dibs device is reachable via this local device
+	 * and this vlan id.
+	 * Return: 0 if remote gid is reachable.
+	 */
+	int (*query_remote_gid)(struct dibs_dev *dev, const uuid_t *rgid,
+				u32 vid_valid, u32 vid);
+	/**
+	 * max_dmbs()
+	 * Return: Max number of DMBs that can be registered for this kind of
+	 *	   dibs_dev
+	 */
+	int (*max_dmbs)(void);
+	/**
+	 * register_dmb() - allocate and register a dmb
+	 * @dev: dibs device
+	 * @dmb: dmb struct to be registered
+	 * @client: dibs client
+	 * @vid: VLAN id; deprecated, ignored if device does not support vlan
+	 *
+	 * The following fields of dmb must provide valid input:
+	 *	@rgid: gid of remote user device
+	 *	@dmb_len: buffer length
+	 *	@idx: Optionally:requested idx (if non-zero)
+	 *	@vlan_valid: if zero, vlan_id will be ignored;
+	 *		     deprecated, ignored if device does not support vlan
+	 *	@vlan_id: deprecated, ignored if device does not support vlan
+	 * Upon return in addition the following fields will be valid:
+	 *	@dmb_tok: for usage by remote and local devices and clients
+	 *	@cpu_addr: allocated buffer
+	 *	@idx: dmb index, unique per dibs device
+	 *	@dma_addr: to be used by device driver,if applicable
+	 *
+	 * Allocate a dmb buffer and register it with this device and for this
+	 * client.
+	 * Return: zero on success
+	 */
+	int (*register_dmb)(struct dibs_dev *dev, struct dibs_dmb *dmb,
+			    struct dibs_client *client);
+	/**
+	 * unregister_dmb() - unregister and free a dmb
+	 * @dev: dibs device
+	 * @dmb: dmb struct to be unregistered
+	 * The following fields of dmb must provide valid input:
+	 *	@dmb_tok
+	 *	@cpu_addr
+	 *	@idx
+	 *
+	 * Free dmb.cpu_addr and unregister the dmb from this device.
+	 * Return: zero on success
+	 */
+	int (*unregister_dmb)(struct dibs_dev *dev, struct dibs_dmb *dmb);
+	/**
+	 * move_data() - write into a remote dmb
+	 * @dev: Local sending dibs device
+	 * @dmb_tok: Token of the remote dmb
+	 * @idx: signaling index in dmbemask
+	 * @sf: signaling flag;
+	 *      if true, idx will be turned on at target dmbemask mask
+	 *      and target device will be signaled.
+	 * @offset: offset within target dmb
+	 * @data: pointer to data to be sent
+	 * @size: length of data to be sent, can be zero.
+	 *
+	 * Use dev to write data of size at offset into a remote dmb
+	 * identified by dmb_tok. Data is moved synchronously, *data can
+	 * be freed when this function returns.
+	 *
+	 * If signaling flag (sf) is true, bit number idx bit will be turned
+	 * on in the dmbemask mask when handle_irq() is called at the remote
+	 * dibs client that owns the target dmb. The target device may chose
+	 * to coalesce the signaling triggers of multiple move_data() calls
+	 * to the same target dmb into a single handle_irq() call.
+	 * Return: zero on success
+	 */
+	int (*move_data)(struct dibs_dev *dev, u64 dmb_tok, unsigned int idx,
+			 bool sf, unsigned int offset, void *data,
+			 unsigned int size);
+	/**
+	 * add_vlan_id() - add dibs device to vlan (optional, deprecated)
+	 * @dev: dibs device
+	 * @vlan_id: vlan id
+	 *
+	 * In order to write into a vlan-tagged dmb, the remote device needs
+	 * to belong to the this vlan. A device can belong to more than 1 vlan.
+	 * Any device can access an untagged dmb.
+	 * Deprecated, only supported for backwards compatibility.
+	 * Return: zero on success
+	 */
+	int (*add_vlan_id)(struct dibs_dev *dev, u64 vlan_id);
+	/**
+	 * del_vlan_id() - remove dibs device from vlan (optional, deprecated)
+	 * @dev: dibs device
+	 * @vlan_id: vlan id
+	 * Return: zero on success
+	 */
+	int (*del_vlan_id)(struct dibs_dev *dev, u64 vlan_id);
+	/**
+	 * signal_event() - trigger an event at a remote dibs device (optional)
+	 * @dev: local dibs device
+	 * @rgid: gid of remote dibs device
+	 * trigger_irq: zero: notification may be coalesced with other events
+	 *		non-zero: notify immediately
+	 * @subtype: 4 byte event code, meaning is defined by dibs client
+	 * @data: 8 bytes of additional information,
+	 *	  meaning is defined by dibs client
+	 *
+	 * dibs devices can offer support for sending a control event of type
+	 * EVENT_SWR to a remote dibs device.
+	 * NOTE: handle_event() will be called for all registered dibs clients
+	 * at the remote device.
+	 * Return: zero on success
+	 */
+	int (*signal_event)(struct dibs_dev *dev, const uuid_t *rgid,
+			    u32 trigger_irq, u32 event_code, u64 info);
+	/**
+	 * support_mmapped_rdmb() - can this device provide memory mapped
+	 *			    remote dmbs? (optional)
+	 * @dev: dibs device
+	 *
+	 * A dibs device can provide a kernel address + length, that represent
+	 * a remote target dmb (like MMIO). Alternatively to calling
+	 * move_data(), a dibs client can write into such a ghost-send-buffer
+	 * (= to this kernel address) and the data will automatically
+	 * immediately appear in the target dmb, even without calling
+	 * move_data().
+	 *
+	 * Either all 3 function pointers for support_dmb_nocopy(),
+	 * attach_dmb() and detach_dmb() are defined, or all of them must
+	 * be NULL.
+	 *
+	 * Return: non-zero, if memory mapped remote dmbs are supported.
+	 */
+	int (*support_mmapped_rdmb)(struct dibs_dev *dev);
+	/**
+	 * attach_dmb() - attach local memory to a remote dmb
+	 * @dev: Local sending ism device
+	 * @dmb: all other parameters are passed in the form of a
+	 *	 dmb struct
+	 *	 TODO: (THIS IS CONFUSING, should be changed)
+	 *  dmb_tok: (in) Token of the remote dmb, we want to attach to
+	 *  cpu_addr: (out) MMIO address
+	 *  dma_addr: (out) MMIO address (if applicable, invalid otherwise)
+	 *  dmb_len: (out) length of local MMIO region,
+	 *           equal to length of remote DMB.
+	 *  sba_idx: (out) index of remote dmb (NOT HELPFUL, should be removed)
+	 *
+	 * Provides a memory address to the sender that can be used to
+	 * directly write into the remote dmb.
+	 * Memory is available until detach_dmb is called
+	 *
+	 * Return: Zero upon success, Error code otherwise
+	 */
+	int (*attach_dmb)(struct dibs_dev *dev, struct dibs_dmb *dmb);
+	/**
+	 * detach_dmb() - Detach the ghost buffer from a remote dmb
+	 * @dev: ism device
+	 * @token: dmb token of the remote dmb
+	 *
+	 * No need to free cpu_addr.
+	 *
+	 * Return: Zero upon success, Error code otherwise
+	 */
+	int (*detach_dmb)(struct dibs_dev *dev, u64 token);
+};
+
+struct dibs_dev {
+	struct list_head list;
+	struct device dev;
+	/* To be filled by device driver, before calling dibs_dev_add(): */
+	const struct dibs_dev_ops *ops;
+	uuid_t gid;
+	/* priv pointer for device driver */
+	void *drv_priv;
+
+	/* priv pointer per client; for client usage only */
+	void *priv[MAX_DIBS_CLIENTS];
+
+	/* get this lock before accessing any of the fields below */
+	spinlock_t lock;
+	/* array of client ids indexed by dmb idx;
+	 * can be used as indices into priv and subs arrays
+	 */
+	u8 *dmb_clientid_arr;
+	/* Sparse array of all ISM clients */
+	struct dibs_client *subs[MAX_DIBS_CLIENTS];
+};
+
+static inline void dibs_set_priv(struct dibs_dev *dev,
+				 struct dibs_client *client, void *priv)
+{
+	dev->priv[client->id] = priv;
+}
+
+static inline void *dibs_get_priv(struct dibs_dev *dev,
+				  struct dibs_client *client)
+{
+	return dev->priv[client->id];
+}
+
+/* ------- End of client-only functions ----------- */
+
+/* Functions to be called by dibs device drivers:
+ */
+/**
+ * dibs_dev_alloc() - allocate and reference device structure
+ *
+ * The following fields will be valid upon successful return: dev
+ * NOTE: Use put_device(dibs_get_dev(@dibs)) to give up your reference instead
+ * of freeing @dibs @dev directly once you have successfully called this
+ * function.
+ * Return: Pointer to dibs device structure
+ */
+struct dibs_dev *dibs_dev_alloc(void);
+/**
+ * dibs_dev_add() - register with dibs layer and all clients
+ * @dibs: dibs device
+ *
+ * The following fields must be valid upon entry: dev, ops, drv_priv
+ * All fields will be valid upon successful return.
+ * Return: zero on success
+ */
+int dibs_dev_add(struct dibs_dev *dibs);
+/**
+ * dibs_dev_del() - unregister from dibs layer and all clients
+ * @dibs: dibs device
+ */
+void dibs_dev_del(struct dibs_dev *dibs);
+
+#endif	/* _DIBS_H */

include/linux/ism.h

···
 
 #include <linux/workqueue.h>
 
-struct ism_dmb {
-	u64 dmb_tok;
-	u64 rgid;
-	u32 dmb_len;
-	u32 sba_idx;
-	u32 vlan_valid;
-	u32 vlan_id;
-	void *cpu_addr;
-	dma_addr_t dma_addr;
-};
-
 /* Unless we gain unexpected popularity, this limit should hold for a while */
 #define MAX_CLIENTS		8
 #define ISM_NR_DMBS		1920
···
 	spinlock_t lock; /* protects the ism device */
 	spinlock_t cmd_lock; /* serializes cmds */
 	struct list_head list;
+	struct dibs_dev *dibs;
 	struct pci_dev *pdev;
 
 	struct ism_sba *sba;
 	dma_addr_t sba_dma_addr;
 	DECLARE_BITMAP(sba_bitmap, ISM_NR_DMBS);
-	u8 *sba_client_arr;	/* entries are indices into 'clients' array */
 	void *priv[MAX_CLIENTS];
 
 	struct ism_eq *ieq;
 	dma_addr_t ieq_dma_addr;
 
-	struct device dev;
-	u64 local_gid;
 	int ieq_idx;
 
 	struct ism_client *subs[MAX_CLIENTS];
···
 
 struct ism_client {
 	const char *name;
-	void (*add)(struct ism_dev *dev);
-	void (*remove)(struct ism_dev *dev);
 	void (*handle_event)(struct ism_dev *dev, struct ism_event *event);
-	/* Parameter dmbemask contains a bit vector with updated DMBEs, if sent
-	 * via ism_move_data(). Callback function must handle all active bits
-	 * indicated by dmbemask.
-	 */
-	void (*handle_irq)(struct ism_dev *dev, unsigned int bit, u16 dmbemask);
 	/* Private area - don't touch! */
 	u8 id;
 };
···
 				void *priv) {
 	dev->priv[client->id] = priv;
 }
-
-int  ism_register_dmb(struct ism_dev *dev, struct ism_dmb *dmb,
-		      struct ism_client *client);
-int  ism_unregister_dmb(struct ism_dev *dev, struct ism_dmb *dmb);
-int  ism_move(struct ism_dev *dev, u64 dmb_tok, unsigned int idx, bool sf,
-	      unsigned int offset, void *data, unsigned int size);
 
 const struct smcd_ops *ism_get_smcd_ops(void);
 

include/net/smc.h

···
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/wait.h>
-#include "linux/ism.h"
+#include <linux/dibs.h>
 
 struct sock;
 
···
 };
 
 /* SMCD/ISM device driver interface */
-struct smcd_dmb {
-	u64 dmb_tok;
-	u64 rgid;
-	u32 dmb_len;
-	u32 sba_idx;
-	u32 vlan_valid;
-	u32 vlan_id;
-	void *cpu_addr;
-	dma_addr_t dma_addr;
-};
-
-#define ISM_EVENT_DMB	0
-#define ISM_EVENT_GID	1
-#define ISM_EVENT_SWR	2
-
 #define ISM_RESERVED_VLANID	0x1FFF
-
-#define ISM_ERROR	0xFFFF
-
-struct smcd_dev;
 
 struct smcd_gid {
 	u64	gid;
 	u64	gid_ext;
 };
 
-struct smcd_ops {
-	int (*query_remote_gid)(struct smcd_dev *dev, struct smcd_gid *rgid,
-				u32 vid_valid, u32 vid);
-	int (*register_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb,
-			    void *client);
-	int (*unregister_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
-	int (*move_data)(struct smcd_dev *dev, u64 dmb_tok, unsigned int idx,
-			 bool sf, unsigned int offset, void *data,
-			 unsigned int size);
-	int (*supports_v2)(void);
-	void (*get_local_gid)(struct smcd_dev *dev, struct smcd_gid *gid);
-	u16 (*get_chid)(struct smcd_dev *dev);
-	struct device* (*get_dev)(struct smcd_dev *dev);
-
-	/* optional operations */
-	int (*add_vlan_id)(struct smcd_dev *dev, u64 vlan_id);
-	int (*del_vlan_id)(struct smcd_dev *dev, u64 vlan_id);
-	int (*set_vlan_required)(struct smcd_dev *dev);
-	int (*reset_vlan_required)(struct smcd_dev *dev);
-	int (*signal_event)(struct smcd_dev *dev, struct smcd_gid *rgid,
-			    u32 trigger_irq, u32 event_code, u64 info);
-	int (*support_dmb_nocopy)(struct smcd_dev *dev);
-	int (*attach_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
-	int (*detach_dmb)(struct smcd_dev *dev, u64 token);
-};
-
 struct smcd_dev {
-	const struct smcd_ops *ops;
-	void *priv;
-	void *client;
+	struct dibs_dev *dibs;
 	struct list_head list;
 	spinlock_t lock;
 	struct smc_connection **conn;

net/Kconfig

···
 source "net/xfrm/Kconfig"
 source "net/iucv/Kconfig"
 source "net/smc/Kconfig"
+source "drivers/dibs/Kconfig"
 source "net/xdp/Kconfig"
 
 config NET_HANDSHAKE

net/smc/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
 config SMC
 	tristate "SMC socket protocol family"
-	depends on INET && INFINIBAND
-	depends on m || ISM != m
+	depends on INET && INFINIBAND && DIBS
 	help
 	  SMC-R provides a "sockets over RDMA" solution making use of
 	  RDMA over Converged Ethernet (RoCE) technology to upgrade
···
 	  smcss.
 
 	  if unsure, say Y.
-
-config SMC_LO
-	bool "SMC intra-OS shortcut with loopback-ism"
-	depends on SMC
-	default n
-	help
-	  SMC_LO enables the creation of an Emulated-ISM device named
-	  loopback-ism in SMC and makes use of it for transferring data
-	  when communication occurs within the same OS. This helps in
-	  convenient testing of SMC-D since loopback-ism is independent
-	  of architecture or hardware.
-
-	  if unsure, say N.

net/smc/Makefile

···
 smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
 smc-y += smc_tracepoint.o smc_inet.o
 smc-$(CONFIG_SYSCTL) += smc_sysctl.o
-smc-$(CONFIG_SMC_LO) += smc_loopback.o

net/smc/af_smc.c

···
 #include "smc_stats.h"
 #include "smc_tracepoint.h"
 #include "smc_sysctl.h"
-#include "smc_loopback.h"
 #include "smc_inet.h"
 
 static DEFINE_MUTEX(smc_server_lgr_pending);	/* serialize link group
···
 		goto out_sock;
 	}
 
-	rc = smc_loopback_init();
-	if (rc) {
-		pr_err("%s: smc_loopback_init fails with %d\n", __func__, rc);
-		goto out_ib;
-	}
-
 	rc = tcp_register_ulp(&smc_ulp_ops);
 	if (rc) {
 		pr_err("%s: tcp_ulp_register fails with %d\n", __func__, rc);
-		goto out_lo;
+		goto out_ib;
 	}
 	rc = smc_inet_init();
 	if (rc) {
···
 	return 0;
 out_ulp:
 	tcp_unregister_ulp(&smc_ulp_ops);
-out_lo:
-	smc_loopback_exit();
 out_ib:
 	smc_ib_unregister_client();
 out_sock:
···
 	tcp_unregister_ulp(&smc_ulp_ops);
 	sock_unregister(PF_SMC);
 	smc_core_exit();
-	smc_loopback_exit();
 	smc_ib_unregister_client();
 	smc_ism_exit();
 	destroy_workqueue(smc_close_wq);

net/smc/smc_clc.c

···
 		/* add SMC-D specifics */
 		if (ini->ism_dev[0]) {
 			smcd = ini->ism_dev[0];
-			smcd->ops->get_local_gid(smcd, &smcd_gid);
+			copy_to_smcdgid(&smcd_gid, &smcd->dibs->gid);
 			pclc_smcd->ism.gid = htonll(smcd_gid.gid);
 			pclc_smcd->ism.chid =
 				htons(smc_ism_get_chid(ini->ism_dev[0]));
···
 		if (ini->ism_offered_cnt) {
 			for (i = 1; i <= ini->ism_offered_cnt; i++) {
 				smcd = ini->ism_dev[i];
-				smcd->ops->get_local_gid(smcd, &smcd_gid);
+				copy_to_smcdgid(&smcd_gid, &smcd->dibs->gid);
 				gidchids[entry].chid =
 					htons(smc_ism_get_chid(ini->ism_dev[i]));
 				gidchids[entry].gid = htonll(smcd_gid.gid);
···
 	/* SMC-D specific settings */
 	memcpy(clc->hdr.eyecatcher, SMCD_EYECATCHER,
 	       sizeof(SMCD_EYECATCHER));
-	smcd->ops->get_local_gid(smcd, &smcd_gid);
+	copy_to_smcdgid(&smcd_gid, &smcd->dibs->gid);
 	clc->hdr.typev1 = SMC_TYPE_D;
 	clc->d0.gid = htonll(smcd_gid.gid);
 	clc->d0.token = htonll(conn->rmb_desc->token);

net/smc/smc_core.c

···
 
 	if (nla_put_u32(skb, SMC_NLA_LGR_D_ID, *((u32 *)&lgr->id)))
 		goto errattr;
-	smcd->ops->get_local_gid(smcd, &smcd_gid);
+	copy_to_smcdgid(&smcd_gid, &smcd->dibs->gid);
 	if (nla_put_u64_64bit(skb, SMC_NLA_LGR_D_GID,
 			      smcd_gid.gid, SMC_NLA_LGR_D_PAD))
 		goto errattr;
···
 	if (ini->is_smcd) {
 		/* SMC-D specific settings */
 		smcd = ini->ism_dev[ini->ism_selected];
-		get_device(smcd->ops->get_dev(smcd));
+		get_device(&smcd->dibs->dev);
 		lgr->peer_gid.gid =
 			ini->ism_peer_gid[ini->ism_selected].gid;
 		lgr->peer_gid.gid_ext =
···
 	destroy_workqueue(lgr->tx_wq);
 	if (lgr->is_smcd) {
 		smc_ism_put_vlan(lgr->smcd, lgr->vlan_id);
-		put_device(lgr->smcd->ops->get_dev(lgr->smcd));
+		put_device(&lgr->smcd->dibs->dev);
 	}
 	smc_lgr_put(lgr); /* theoretically last lgr_put */
 }

net/smc/smc_core.h

···
 #define _SMC_CORE_H
 
 #include <linux/atomic.h>
+#include <linux/types.h>
 #include <linux/smc.h>
 #include <linux/pci.h>
 #include <rdma/ib_verbs.h>
···
 					/* virtually contiguous */
 		};
 		struct { /* SMC-D */
+			/* SMC-D tx buffer */
+			bool		is_attached;
+					/* no need for explicit writes */
+			 /* SMC-D rx buffer: */
 			unsigned short	sba_idx;
 					/* SBA index number */
 			u64		token;

net/smc/smc_diag.c

···
 		dinfo.linkid = *((u32 *)conn->lgr->id);
 		dinfo.peer_gid = conn->lgr->peer_gid.gid;
 		dinfo.peer_gid_ext = conn->lgr->peer_gid.gid_ext;
-		smcd->ops->get_local_gid(smcd, &smcd_gid);
+		copy_to_smcdgid(&smcd_gid, &smcd->dibs->gid);
 		dinfo.my_gid = smcd_gid.gid;
 		dinfo.my_gid_ext = smcd_gid.gid_ext;
 		dinfo.token = conn->rmb_desc->token;

net/smc/smc_ism.c

···
 #include "smc_ism.h"
 #include "smc_pnet.h"
 #include "smc_netlink.h"
-#include "linux/ism.h"
+#include "linux/dibs.h"
 
 struct smcd_dev_list smcd_dev_list = {
 	.list = LIST_HEAD_INIT(smcd_dev_list.list),
···
 static bool smc_ism_v2_capable;
 static u8 smc_ism_v2_system_eid[SMC_MAX_EID_LEN];
 
-#if IS_ENABLED(CONFIG_ISM)
-static void smcd_register_dev(struct ism_dev *ism);
-static void smcd_unregister_dev(struct ism_dev *ism);
-static void smcd_handle_event(struct ism_dev *ism, struct ism_event *event);
-static void smcd_handle_irq(struct ism_dev *ism, unsigned int dmbno,
+static void smcd_register_dev(struct dibs_dev *dibs);
+static void smcd_unregister_dev(struct dibs_dev *dibs);
+static void smcd_handle_event(struct dibs_dev *dibs,
+			      const struct dibs_event *event);
+static void smcd_handle_irq(struct dibs_dev *dibs, unsigned int dmbno,
 			    u16 dmbemask);
 
-static struct ism_client smc_ism_client = {
-	.name = "SMC-D",
-	.add = smcd_register_dev,
-	.remove = smcd_unregister_dev,
+static struct dibs_client_ops smc_client_ops = {
+	.add_dev = smcd_register_dev,
+	.del_dev = smcd_unregister_dev,
 	.handle_event = smcd_handle_event,
 	.handle_irq = smcd_handle_irq,
 };
-#endif
+
+static struct dibs_client smc_dibs_client = {
+	.name = "SMC-D",
+	.ops = &smc_client_ops,
+};
 
 static void smc_ism_create_system_eid(void)
 {
···
 int smc_ism_cantalk(struct smcd_gid *peer_gid, unsigned short vlan_id,
 		    struct smcd_dev *smcd)
 {
-	return smcd->ops->query_remote_gid(smcd, peer_gid, vlan_id ? 1 : 0,
-					   vlan_id);
+	struct dibs_dev *dibs = smcd->dibs;
+	uuid_t ism_rgid;
+
+	copy_to_dibsgid(&ism_rgid, peer_gid);
+	return dibs->ops->query_remote_gid(dibs, &ism_rgid, vlan_id ? 1 : 0,
+					  vlan_id);
 }
 
 void smc_ism_get_system_eid(u8 **eid)
···
 
 u16 smc_ism_get_chid(struct smcd_dev *smcd)
 {
-	return smcd->ops->get_chid(smcd);
+	return smcd->dibs->ops->get_fabric_id(smcd->dibs);
 }
 
 /* HW supports ISM V2 and thus System EID is defined */
···
 
 	if (!vlanid)			/* No valid vlan id */
 		return -EINVAL;
-	if (!smcd->ops->add_vlan_id)
+	if (!smcd->dibs->ops->add_vlan_id)
 		return -EOPNOTSUPP;
 
 	/* create new vlan entry, in case we need it */
···
 	/* no existing entry found.
 	 * add new entry to device; might fail, e.g., if HW limit reached
 	 */
-	if (smcd->ops->add_vlan_id(smcd, vlanid)) {
+	if (smcd->dibs->ops->add_vlan_id(smcd->dibs, vlanid)) {
 		kfree(new_vlan);
 		rc = -EIO;
 		goto out;
···
 
 	if (!vlanid)			/* No valid vlan id */
 		return -EINVAL;
-	if (!smcd->ops->del_vlan_id)
+	if (!smcd->dibs->ops->del_vlan_id)
 		return -EOPNOTSUPP;
 
 	spin_lock_irqsave(&smcd->lock, flags);
···
 	}
 
 	/* Found and the last reference just gone */
-	if (smcd->ops->del_vlan_id(smcd, vlanid))
+	if (smcd->dibs->ops->del_vlan_id(smcd->dibs, vlanid))
 		rc = -EIO;
 	list_del(&vlan->list);
 	kfree(vlan);
···
 	return rc;
 }
 
-int smc_ism_unregister_dmb(struct smcd_dev *smcd, struct smc_buf_desc *dmb_desc)
+void smc_ism_unregister_dmb(struct smcd_dev *smcd,
+			    struct smc_buf_desc *dmb_desc)
 {
-	struct smcd_dmb dmb;
-	int rc = 0;
+	struct dibs_dmb dmb;
 
 	if (!dmb_desc->dma_addr)
-		return rc;
+		return;
 
 	memset(&dmb, 0, sizeof(dmb));
 	dmb.dmb_tok = dmb_desc->token;
-	dmb.sba_idx = dmb_desc->sba_idx;
+	dmb.idx = dmb_desc->sba_idx;
 	dmb.cpu_addr = dmb_desc->cpu_addr;
 	dmb.dma_addr = dmb_desc->dma_addr;
 	dmb.dmb_len = dmb_desc->len;
-	rc = smcd->ops->unregister_dmb(smcd, &dmb);
-	if (!rc || rc == ISM_ERROR) {
-		dmb_desc->cpu_addr = NULL;
-		dmb_desc->dma_addr = 0;
-	}
 
-	return rc;
+	smcd->dibs->ops->unregister_dmb(smcd->dibs, &dmb);
+
+	return;
 }
 
 int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
 			 struct smc_buf_desc *dmb_desc)
 {
-	struct smcd_dmb dmb;
+	struct dibs_dev *dibs;
+	struct dibs_dmb dmb;
 	int rc;
 
 	memset(&dmb, 0, sizeof(dmb));
 	dmb.dmb_len = dmb_len;
-	dmb.sba_idx = dmb_desc->sba_idx;
+	dmb.idx = dmb_desc->sba_idx;
 	dmb.vlan_id = lgr->vlan_id;
-	dmb.rgid = lgr->peer_gid.gid;
-	rc = lgr->smcd->ops->register_dmb(lgr->smcd, &dmb, lgr->smcd->client);
+	copy_to_dibsgid(&dmb.rgid, &lgr->peer_gid);
+
+	dibs = lgr->smcd->dibs;
+	rc = dibs->ops->register_dmb(dibs, &dmb, &smc_dibs_client);
 	if (!rc) {
-		dmb_desc->sba_idx = dmb.sba_idx;
+		dmb_desc->sba_idx = dmb.idx;
 		dmb_desc->token = dmb.dmb_tok;
 		dmb_desc->cpu_addr = dmb.cpu_addr;
 		dmb_desc->dma_addr = dmb.dma_addr;
···
 	 * merging sndbuf with peer DMB to avoid
 	 * data copies between them.
 	 */
-	return (smcd->ops->support_dmb_nocopy &&
-		smcd->ops->support_dmb_nocopy(smcd));
+	return (smcd->dibs->ops->support_mmapped_rdmb &&
+		smcd->dibs->ops->support_mmapped_rdmb(smcd->dibs));
 }
 
 int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
 		       struct smc_buf_desc *dmb_desc)
 {
-	struct smcd_dmb dmb;
+	struct dibs_dmb dmb;
 	int rc = 0;
 
-	if (!dev->ops->attach_dmb)
+	if (!dev->dibs->ops->attach_dmb)
 		return -EINVAL;
 
 	memset(&dmb, 0, sizeof(dmb));
 	dmb.dmb_tok = token;
-	rc = dev->ops->attach_dmb(dev, &dmb);
+	rc = dev->dibs->ops->attach_dmb(dev->dibs, &dmb);
 	if (!rc) {
-		dmb_desc->sba_idx = dmb.sba_idx;
+		dmb_desc->sba_idx = dmb.idx;
 		dmb_desc->token = dmb.dmb_tok;
 		dmb_desc->cpu_addr = dmb.cpu_addr;
 		dmb_desc->dma_addr = dmb.dma_addr;
 		dmb_desc->len = dmb.dmb_len;
+		dmb_desc->is_attached = true;
 	}
 	return rc;
 }
 
 int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token)
 {
-	if (!dev->ops->detach_dmb)
+	if (!dev->dibs->ops->detach_dmb)
 		return -EINVAL;
 
-	return dev->ops->detach_dmb(dev, token);
+	return dev->dibs->ops->detach_dmb(dev->dibs, token);
 }
 
 static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
···
 	char smc_pnet[SMC_MAX_PNETID_LEN + 1];
 	struct smc_pci_dev smc_pci_dev;
 	struct nlattr *port_attrs;
+	struct dibs_dev *dibs;
 	struct nlattr *attrs;
-	struct ism_dev *ism;
 	int use_cnt = 0;
 	void *nlh;
 
-	ism = smcd->priv;
+	dibs = smcd->dibs;
 	nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 			  &smc_gen_nl_family, NLM_F_MULTI,
 			  SMC_NETLINK_GET_DEV_SMCD);
···
 	if (nla_put_u8(skb, SMC_NLA_DEV_IS_CRIT, use_cnt > 0))
 		goto errattr;
 	memset(&smc_pci_dev, 0, sizeof(smc_pci_dev));
-	smc_set_pci_values(to_pci_dev(ism->dev.parent), &smc_pci_dev);
+	smc_set_pci_values(to_pci_dev(dibs->dev.parent), &smc_pci_dev);
 	if (nla_put_u32(skb, SMC_NLA_DEV_PCI_FID, smc_pci_dev.pci_fid))
 		goto errattr;
 	if (nla_put_u16(skb, SMC_NLA_DEV_PCI_CHID, smc_pci_dev.pci_pchid))
···
 	list_for_each_entry(smcd, &dev_list->list, list) {
 		if (num < snum)
 			goto next;
-		if (smc_ism_is_loopback(smcd))
+		if (smc_ism_is_loopback(smcd->dibs))
 			goto next;
 		if (smc_nl_handle_smcd_dev(smcd, skb, cb))
 			goto errout;
···
 	return skb->len;
 }
 
-#if IS_ENABLED(CONFIG_ISM)
 struct smc_ism_event_work {
 	struct work_struct work;
 	struct smcd_dev *smcd;
-	struct ism_event event;
+	struct dibs_event event;
 };
 
 #define ISM_EVENT_REQUEST		0x0001
···
 
 static void smcd_handle_sw_event(struct smc_ism_event_work *wrk)
 {
-	struct smcd_gid peer_gid = { .gid = wrk->event.tok,
-				     .gid_ext = 0 };
+	struct dibs_dev *dibs = wrk->smcd->dibs;
 	union smcd_sw_event_info ev_info;
+	struct smcd_gid peer_gid;
+	uuid_t ism_rgid;
 
-	ev_info.info = wrk->event.info;
-	switch (wrk->event.code) {
+	copy_to_smcdgid(&peer_gid, &wrk->event.gid);
+	ev_info.info = wrk->event.data;
+	switch (wrk->event.subtype) {
 	case ISM_EVENT_CODE_SHUTDOWN:	/* Peer shut down DMBs */
 		smc_smcd_terminate(wrk->smcd, &peer_gid, ev_info.vlan_id);
 		break;
 	case ISM_EVENT_CODE_TESTLINK:	/* Activity timer */
 		if (ev_info.code == ISM_EVENT_REQUEST &&
-		    wrk->smcd->ops->signal_event) {
+		    dibs->ops->signal_event) {
 			ev_info.code = ISM_EVENT_RESPONSE;
-			wrk->smcd->ops->signal_event(wrk->smcd,
-						     &peer_gid,
-						     ISM_EVENT_REQUEST_IR,
-						     ISM_EVENT_CODE_TESTLINK,
-						     ev_info.info);
-			}
+			copy_to_dibsgid(&ism_rgid, &peer_gid);
+			dibs->ops->signal_event(dibs, &ism_rgid,
+					       ISM_EVENT_REQUEST_IR,
+					       ISM_EVENT_CODE_TESTLINK,
+					       ev_info.info);
+		}
 		break;
 	}
 }
···
 {
 	struct smc_ism_event_work *wrk =
 		container_of(work, struct smc_ism_event_work, work);
-	struct smcd_gid smcd_gid = { .gid = wrk->event.tok,
-				     .gid_ext = 0 };
+	struct smcd_gid smcd_gid;
+
+	copy_to_smcdgid(&smcd_gid, &wrk->event.gid);
 
 	switch (wrk->event.type) {
-	case ISM_EVENT_GID:	/* GID event, token is peer GID */
+	case DIBS_DEV_EVENT: /* GID event, token is peer GID */
 		smc_smcd_terminate(wrk->smcd, &smcd_gid, VLAN_VID_MASK);
 		break;
-	case ISM_EVENT_DMB:
+	case DIBS_BUF_EVENT:
 		break;
-	case ISM_EVENT_SWR:	/* Software defined event */
+	case DIBS_SW_EVENT: /* Software defined event */
 		smcd_handle_sw_event(wrk);
 		break;
 	}
 	kfree(wrk);
 }
 
-static struct smcd_dev *smcd_alloc_dev(struct device *parent, const char *name,
-				       const struct smcd_ops *ops, int max_dmbs)
+static struct smcd_dev *smcd_alloc_dev(const char *name, int max_dmbs)
 {
 	struct smcd_dev *smcd;
 
-	smcd = devm_kzalloc(parent, sizeof(*smcd), GFP_KERNEL);
+	smcd = kzalloc(sizeof(*smcd), GFP_KERNEL);
 	if (!smcd)
 		return NULL;
-	smcd->conn = devm_kcalloc(parent, max_dmbs,
-				  sizeof(struct smc_connection *), GFP_KERNEL);
+	smcd->conn = kcalloc(max_dmbs, sizeof(struct smc_connection *),
+			     GFP_KERNEL);
 	if (!smcd->conn)
-		return NULL;
+		goto free_smcd;
 
 	smcd->event_wq = alloc_ordered_workqueue("ism_evt_wq-%s)",
 						 WQ_MEM_RECLAIM, name);
 	if (!smcd->event_wq)
-		return NULL;
-
-	smcd->ops = ops;
+		goto free_conn;
 
 	spin_lock_init(&smcd->lock);
 	spin_lock_init(&smcd->lgr_lock);
···
 	INIT_LIST_HEAD(&smcd->lgr_list);
 	init_waitqueue_head(&smcd->lgrs_deleted);
 	return smcd;
+
+free_conn:
+	kfree(smcd->conn);
+free_smcd:
+	kfree(smcd);
+	return NULL;
 }
 
-static void smcd_register_dev(struct ism_dev *ism)
+static void smcd_register_dev(struct dibs_dev *dibs)
 {
-	const struct smcd_ops *ops = ism_get_smcd_ops();
 	struct smcd_dev *smcd, *fentry;
+	int max_dmbs;
 
-	if (!ops)
-		return;
+	max_dmbs = dibs->ops->max_dmbs();
 
-	smcd = smcd_alloc_dev(&ism->pdev->dev, dev_name(&ism->pdev->dev), ops,
-			      ISM_NR_DMBS);
+	smcd = smcd_alloc_dev(dev_name(&dibs->dev), max_dmbs);
 	if (!smcd)
 		return;
-	smcd->priv = ism;
-	smcd->client = &smc_ism_client;
-	ism_set_priv(ism, &smc_ism_client, smcd);
-	if (smc_pnetid_by_dev_port(&ism->pdev->dev, 0, smcd->pnetid))
+
+	smcd->dibs = dibs;
+	dibs_set_priv(dibs, &smc_dibs_client, smcd);
+
+	if (smc_pnetid_by_dev_port(dibs->dev.parent, 0, smcd->pnetid))
 		smc_pnetid_by_table_smcd(smcd);
 
-	if (smcd->ops->supports_v2())
+	if (smc_ism_is_loopback(dibs) ||
+	    (dibs->ops->add_vlan_id &&
+	     !dibs->ops->add_vlan_id(dibs, ISM_RESERVED_VLANID))) {
 		smc_ism_set_v2_capable();
+	}
+
 	mutex_lock(&smcd_dev_list.mutex);
 	/* sort list:
 	 * - devices without pnetid before devices with pnetid;
···
 	if (!smcd->pnetid[0]) {
 		fentry = list_first_entry_or_null(&smcd_dev_list.list,
 						  struct smcd_dev, list);
-		if (fentry && smc_ism_is_loopback(fentry))
+		if (fentry && smc_ism_is_loopback(fentry->dibs))
 			list_add(&smcd->list, &fentry->list);
 		else
 			list_add(&smcd->list, &smcd_dev_list.list);
···
 
 	if (smc_pnet_is_pnetid_set(smcd->pnetid))
 		pr_warn_ratelimited("smc: adding smcd device %s with pnetid %.16s%s\n",
-				    dev_name(&ism->dev), smcd->pnetid,
+				    dev_name(&dibs->dev), smcd->pnetid,
 				    smcd->pnetid_by_user ?
 					" (user defined)" :
 					"");
 	else
 		pr_warn_ratelimited("smc: adding smcd device %s without pnetid\n",
-				    dev_name(&ism->dev));
+				    dev_name(&dibs->dev));
 	return;
 }
 
-static void smcd_unregister_dev(struct ism_dev *ism)
+static void smcd_unregister_dev(struct dibs_dev *dibs)
 {
-	struct smcd_dev *smcd = ism_get_priv(ism, &smc_ism_client);
+	struct smcd_dev *smcd = dibs_get_priv(dibs, &smc_dibs_client);
 
 	pr_warn_ratelimited("smc: removing smcd device %s\n",
-			    dev_name(&ism->dev));
+			    dev_name(&dibs->dev));
 	smcd->going_away = 1;
 	smc_smcd_terminate_all(smcd);
 	mutex_lock(&smcd_dev_list.mutex);
 	list_del_init(&smcd->list);
 	mutex_unlock(&smcd_dev_list.mutex);
 	destroy_workqueue(smcd->event_wq);
+	kfree(smcd->conn);
+	kfree(smcd);
 }
 
 /* SMCD Device event handler. Called from ISM device interrupt handler.
···
  * Context:
  * - Function called in IRQ context from ISM device driver event handler.
  */
-static void smcd_handle_event(struct ism_dev *ism, struct ism_event *event)
+static void smcd_handle_event(struct dibs_dev *dibs,
+			      const struct dibs_event *event)
 {
-	struct smcd_dev *smcd = ism_get_priv(ism, &smc_ism_client);
+	struct smcd_dev *smcd = dibs_get_priv(dibs, &smc_dibs_client);
 	struct smc_ism_event_work *wrk;
 
 	if (smcd->going_away)
···
  * Context:
  * - Function called in IRQ context from ISM device driver IRQ handler.
  */
-static void smcd_handle_irq(struct ism_dev *ism, unsigned int dmbno,
+static void smcd_handle_irq(struct dibs_dev *dibs, unsigned int dmbno,
 			    u16 dmbemask)
 {
-	struct smcd_dev *smcd = ism_get_priv(ism, &smc_ism_client);
+	struct smcd_dev *smcd = dibs_get_priv(dibs, &smc_dibs_client);
 	struct smc_connection *conn = NULL;
 	unsigned long flags;
 
···
 		tasklet_schedule(&conn->rx_tsklet);
 	spin_unlock_irqrestore(&smcd->lock, flags);
 }
-#endif
 
 int smc_ism_signal_shutdown(struct smc_link_group *lgr)
 {
 	int rc = 0;
-#if IS_ENABLED(CONFIG_ISM)
 	union smcd_sw_event_info ev_info;
+	uuid_t ism_rgid;
 
 	if (lgr->peer_shutdown)
 		return 0;
-	if (!lgr->smcd->ops->signal_event)
+	if (!lgr->smcd->dibs->ops->signal_event)
 		return 0;
 
 	memcpy(ev_info.uid, lgr->id, SMC_LGR_ID_SIZE);
 	ev_info.vlan_id = lgr->vlan_id;
 	ev_info.code = ISM_EVENT_REQUEST;
-	rc = lgr->smcd->ops->signal_event(lgr->smcd, &lgr->peer_gid,
+	copy_to_dibsgid(&ism_rgid, &lgr->peer_gid);
+	rc = lgr->smcd->dibs->ops->signal_event(lgr->smcd->dibs, &ism_rgid,
 					  ISM_EVENT_REQUEST_IR,
 					  ISM_EVENT_CODE_SHUTDOWN,
 					  ev_info.info);
-#endif
 	return rc;
 }
 
···
 	smc_ism_v2_capable = false;
 	smc_ism_create_system_eid();
 
-#if IS_ENABLED(CONFIG_ISM)
-	rc = ism_register_client(&smc_ism_client);
-#endif
+	rc = dibs_register_client(&smc_dibs_client);
 	return rc;
 }
 
 void smc_ism_exit(void)
 {
-#if IS_ENABLED(CONFIG_ISM)
-	ism_unregister_client(&smc_ism_client);
-#endif
+	dibs_unregister_client(&smc_dibs_client);
 }

net/smc/smc_ism.h

···
 #include <linux/uio.h>
 #include <linux/types.h>
 #include <linux/mutex.h>
+#include <linux/dibs.h>
 
 #include "smc.h"
 
···
 int smc_ism_put_vlan(struct smcd_dev *dev, unsigned short vlan_id);
 int smc_ism_register_dmb(struct smc_link_group *lgr, int buf_size,
 			 struct smc_buf_desc *dmb_desc);
-int smc_ism_unregister_dmb(struct smcd_dev *dev, struct smc_buf_desc *dmb_desc);
+void smc_ism_unregister_dmb(struct smcd_dev *dev,
+			    struct smc_buf_desc *dmb_desc);
 bool smc_ism_support_dmb_nocopy(struct smcd_dev *smcd);
 int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
 		       struct smc_buf_desc *dmb_desc);
···
 {
 	int rc;
 
-	rc = smcd->ops->move_data(smcd, dmb_tok, idx, sf, offset, data, len);
+	rc = smcd->dibs->ops->move_data(smcd->dibs, dmb_tok, idx, sf, offset,
+				       data, len);
+
 	return rc < 0 ? rc : 0;
 }
 
···
 
 static inline bool smc_ism_is_emulated(struct smcd_dev *smcd)
 {
-	u16 chid = smcd->ops->get_chid(smcd);
+	u16 chid = smcd->dibs->ops->get_fabric_id(smcd->dibs);
 
 	return __smc_ism_is_emulated(chid);
 }
 
-static inline bool smc_ism_is_loopback(struct smcd_dev *smcd)
+static inline bool smc_ism_is_loopback(struct dibs_dev *dibs)
 {
-	return (smcd->ops->get_chid(smcd) == 0xFFFF);
+	return (dibs->ops->get_fabric_id(dibs) == DIBS_LOOPBACK_FABRIC);
+}
+
+static inline void copy_to_smcdgid(struct smcd_gid *sgid, uuid_t *dibs_gid)
+{
+	__be64 temp;
+
+	memcpy(&temp, dibs_gid, sizeof(sgid->gid));
+	sgid->gid = ntohll(temp);
+	memcpy(&temp, (uint8_t *)dibs_gid + sizeof(sgid->gid),
+	       sizeof(sgid->gid_ext));
+	sgid->gid_ext = ntohll(temp);
+}
+
+static inline void copy_to_dibsgid(uuid_t *dibs_gid, struct smcd_gid *sgid)
+{
+	__be64 temp;
+
+	temp = htonll(sgid->gid);
+	memcpy(dibs_gid, &temp, sizeof(sgid->gid));
+	temp = htonll(sgid->gid_ext);
+	memcpy((uint8_t *)dibs_gid + sizeof(sgid->gid), &temp,
+	       sizeof(sgid->gid_ext));
 }
 
 #endif

net/smc/smc_loopback.c

···
-// SPDX-License-Identifier: GPL-2.0
-/*
- *  Shared Memory Communications Direct over loopback-ism device.
- *
- *  Functions for loopback-ism device.
- *
- *  Copyright (c) 2024, Alibaba Inc.
- *
- *  Author: Wen Gu <[e-mail]>
- *          Tony Lu <[e-mail]>
- *
- */
-
-#include <linux/device.h>
-#include <linux/types.h>
-#include <net/smc.h>
-
-#include "smc_cdc.h"
-#include "smc_ism.h"
-#include "smc_loopback.h"
-
-#define SMC_LO_V2_CAPABLE	0x1 /* loopback-ism acts as ISMv2 */
-#define SMC_LO_SUPPORT_NOCOPY	0x1
-#define SMC_DMA_ADDR_INVALID	(~(dma_addr_t)0)
-
-static const char smc_lo_dev_name[] = "loopback-ism";
-static struct smc_lo_dev *lo_dev;
-
-static void smc_lo_generate_ids(struct smc_lo_dev *ldev)
-{
-	struct smcd_gid *lgid = &ldev->local_gid;
-	uuid_t uuid;
-
-	uuid_gen(&uuid);
-	memcpy(&lgid->gid, &uuid, sizeof(lgid->gid));
-	memcpy(&lgid->gid_ext, (u8 *)&uuid + sizeof(lgid->gid),
-	       sizeof(lgid->gid_ext));
-
-	ldev->chid = SMC_LO_RESERVED_CHID;
-}
-
-static int smc_lo_query_rgid(struct smcd_dev *smcd, struct smcd_gid *rgid,
-			     u32 vid_valid, u32 vid)
-{
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	/* rgid should be the same as lgid */
-	if (!ldev || rgid->gid != ldev->local_gid.gid ||
-	    rgid->gid_ext != ldev->local_gid.gid_ext)
-		return -ENETUNREACH;
-	return 0;
-}
-
-static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
-			       void *client_priv)
-{
-	struct smc_lo_dmb_node *dmb_node, *tmp_node;
-	struct smc_lo_dev *ldev = smcd->priv;
-	int sba_idx, rc;
-
-	/* check space for new dmb */
-	for_each_clear_bit(sba_idx, ldev->sba_idx_mask, SMC_LO_MAX_DMBS) {
-		if (!test_and_set_bit(sba_idx, ldev->sba_idx_mask))
-			break;
-	}
-	if (sba_idx == SMC_LO_MAX_DMBS)
-		return -ENOSPC;
-
-	dmb_node = kzalloc(sizeof(*dmb_node), GFP_KERNEL);
-	if (!dmb_node) {
-		rc = -ENOMEM;
-		goto err_bit;
-	}
-
-	dmb_node->sba_idx = sba_idx;
-	dmb_node->len = dmb->dmb_len;
-	dmb_node->cpu_addr = kzalloc(dmb_node->len, GFP_KERNEL |
-				     __GFP_NOWARN | __GFP_NORETRY |
-				     __GFP_NOMEMALLOC);
-	if (!dmb_node->cpu_addr) {
-		rc = -ENOMEM;
-		goto err_node;
-	}
-	dmb_node->dma_addr = SMC_DMA_ADDR_INVALID;
-	refcount_set(&dmb_node->refcnt, 1);
-
-again:
-	/* add new dmb into hash table */
-	get_random_bytes(&dmb_node->token, sizeof(dmb_node->token));
-	write_lock_bh(&ldev->dmb_ht_lock);
-	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_node->token) {
-		if (tmp_node->token == dmb_node->token) {
-			write_unlock_bh(&ldev->dmb_ht_lock);
-			goto again;
-		}
-	}
-	hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
-	write_unlock_bh(&ldev->dmb_ht_lock);
-	atomic_inc(&ldev->dmb_cnt);
-
-	dmb->sba_idx = dmb_node->sba_idx;
-	dmb->dmb_tok = dmb_node->token;
-	dmb->cpu_addr = dmb_node->cpu_addr;
-	dmb->dma_addr = dmb_node->dma_addr;
-	dmb->dmb_len = dmb_node->len;
-
-	return 0;
-
-err_node:
-	kfree(dmb_node);
-err_bit:
-	clear_bit(sba_idx, ldev->sba_idx_mask);
-	return rc;
-}
-
-static void __smc_lo_unregister_dmb(struct smc_lo_dev *ldev,
-				    struct smc_lo_dmb_node *dmb_node)
-{
-	/* remove dmb from hash table */
-	write_lock_bh(&ldev->dmb_ht_lock);
-	hash_del(&dmb_node->list);
-	write_unlock_bh(&ldev->dmb_ht_lock);
-
-	clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
-	kvfree(dmb_node->cpu_addr);
-	kfree(dmb_node);
-
-	if (atomic_dec_and_test(&ldev->dmb_cnt))
-		wake_up(&ldev->ldev_release);
-}
-
-static int smc_lo_unregister_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
-{
-	struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	/* find dmb from hash table */
-	read_lock_bh(&ldev->dmb_ht_lock);
-	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
-		if (tmp_node->token == dmb->dmb_tok) {
-			dmb_node = tmp_node;
-			break;
-		}
-	}
-	if (!dmb_node) {
-		read_unlock_bh(&ldev->dmb_ht_lock);
-		return -EINVAL;
-	}
-	read_unlock_bh(&ldev->dmb_ht_lock);
-
-	if (refcount_dec_and_test(&dmb_node->refcnt))
-		__smc_lo_unregister_dmb(ldev, dmb_node);
-	return 0;
-}
-
-static int smc_lo_support_dmb_nocopy(struct smcd_dev *smcd)
-{
-	return SMC_LO_SUPPORT_NOCOPY;
-}
-
-static int smc_lo_attach_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
-{
-	struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	/* find dmb_node according to dmb->dmb_tok */
-	read_lock_bh(&ldev->dmb_ht_lock);
-	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
-		if (tmp_node->token == dmb->dmb_tok) {
-			dmb_node = tmp_node;
-			break;
-		}
-	}
-	if (!dmb_node) {
-		read_unlock_bh(&ldev->dmb_ht_lock);
-		return -EINVAL;
-	}
-	read_unlock_bh(&ldev->dmb_ht_lock);
-
-	if (!refcount_inc_not_zero(&dmb_node->refcnt))
-		/* the dmb is being unregistered, but has
-		 * not been removed from the hash table.
-		 */
-		return -EINVAL;
-
-	/* provide dmb information */
-	dmb->sba_idx = dmb_node->sba_idx;
-	dmb->dmb_tok = dmb_node->token;
-	dmb->cpu_addr = dmb_node->cpu_addr;
-	dmb->dma_addr = dmb_node->dma_addr;
-	dmb->dmb_len = dmb_node->len;
-	return 0;
-}
-
-static int smc_lo_detach_dmb(struct smcd_dev *smcd, u64 token)
-{
-	struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	/* find dmb_node according to dmb->dmb_tok */
-	read_lock_bh(&ldev->dmb_ht_lock);
-	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, token) {
-		if (tmp_node->token == token) {
-			dmb_node = tmp_node;
-			break;
-		}
-	}
-	if (!dmb_node) {
-		read_unlock_bh(&ldev->dmb_ht_lock);
-		return -EINVAL;
-	}
-	read_unlock_bh(&ldev->dmb_ht_lock);
-
-	if (refcount_dec_and_test(&dmb_node->refcnt))
-		__smc_lo_unregister_dmb(ldev, dmb_node);
-	return 0;
-}
-
-static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
-			    unsigned int idx, bool sf, unsigned int offset,
-			    void *data, unsigned int size)
-{
-	struct smc_lo_dmb_node *rmb_node = NULL, *tmp_node;
-	struct smc_lo_dev *ldev = smcd->priv;
-	struct smc_connection *conn;
-
-	if (!sf)
-		/* since sndbuf is merged with peer DMB, there is
-		 * no need to copy data from sndbuf to peer DMB.
-		 */
-		return 0;
-
-	read_lock_bh(&ldev->dmb_ht_lock);
-	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
-		if (tmp_node->token == dmb_tok) {
-			rmb_node = tmp_node;
-			break;
-		}
-	}
-	if (!rmb_node) {
-		read_unlock_bh(&ldev->dmb_ht_lock);
-		return -EINVAL;
-	}
-	memcpy((char *)rmb_node->cpu_addr + offset, data, size);
-	read_unlock_bh(&ldev->dmb_ht_lock);
-
-	conn = smcd->conn[rmb_node->sba_idx];
-	if (!conn || conn->killed)
-		return -EPIPE;
-	tasklet_schedule(&conn->rx_tsklet);
-	return 0;
-}
-
-static void smc_lo_get_local_gid(struct smcd_dev *smcd,
-				 struct smcd_gid *smcd_gid)
-{
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	smcd_gid->gid = ldev->local_gid.gid;
-	smcd_gid->gid_ext = ldev->local_gid.gid_ext;
-}
-
-static u16 smc_lo_get_chid(struct smcd_dev *smcd)
-{
-	return ((struct smc_lo_dev *)smcd->priv)->chid;
-}
-
-static struct device *smc_lo_get_dev(struct smcd_dev *smcd)
-{
-	return &((struct smc_lo_dev *)smcd->priv)->dev;
-}
-
-static const struct smcd_ops lo_ops = {
-	.query_remote_gid = smc_lo_query_rgid,
-	.register_dmb = smc_lo_register_dmb,
-	.unregister_dmb = smc_lo_unregister_dmb,
-	.support_dmb_nocopy = smc_lo_support_dmb_nocopy,
-	.attach_dmb = smc_lo_attach_dmb,
-	.detach_dmb = smc_lo_detach_dmb,
-	.add_vlan_id		= NULL,
-	.del_vlan_id		= NULL,
-	.set_vlan_required	= NULL,
-	.reset_vlan_required	= NULL,
-	.signal_event		= NULL,
-	.move_data = smc_lo_move_data,
-	.get_local_gid = smc_lo_get_local_gid,
-	.get_chid = smc_lo_get_chid,
-	.get_dev = smc_lo_get_dev,
-};
-
-static struct smcd_dev *smcd_lo_alloc_dev(const struct smcd_ops *ops,
-					  int max_dmbs)
-{
-	struct smcd_dev *smcd;
-
-	smcd = kzalloc(sizeof(*smcd), GFP_KERNEL);
-	if (!smcd)
-		return NULL;
-
-	smcd->conn = kcalloc(max_dmbs, sizeof(struct smc_connection *),
-			     GFP_KERNEL);
-	if (!smcd->conn)
-		goto out_smcd;
-
-	smcd->ops = ops;
-
-	spin_lock_init(&smcd->lock);
-	spin_lock_init(&smcd->lgr_lock);
-	INIT_LIST_HEAD(&smcd->vlan);
-	INIT_LIST_HEAD(&smcd->lgr_list);
-	init_waitqueue_head(&smcd->lgrs_deleted);
-	return smcd;
-
-out_smcd:
-	kfree(smcd);
-	return NULL;
-}
-
-static int smcd_lo_register_dev(struct smc_lo_dev *ldev)
-{
-	struct smcd_dev *smcd;
-
-	smcd = smcd_lo_alloc_dev(&lo_ops, SMC_LO_MAX_DMBS);
-	if (!smcd)
-		return -ENOMEM;
-	ldev->smcd = smcd;
-	smcd->priv = ldev;
-	smc_ism_set_v2_capable();
-	mutex_lock(&smcd_dev_list.mutex);
-	list_add(&smcd->list, &smcd_dev_list.list);
-	mutex_unlock(&smcd_dev_list.mutex);
-	pr_warn_ratelimited("smc: adding smcd device %s\n",
-			    dev_name(&ldev->dev));
-	return 0;
-}
-
-static void smcd_lo_unregister_dev(struct smc_lo_dev *ldev)
-{
-	struct smcd_dev *smcd = ldev->smcd;
-
-	pr_warn_ratelimited("smc: removing smcd device %s\n",
-			    dev_name(&ldev->dev));
-	smcd->going_away = 1;
-	smc_smcd_terminate_all(smcd);
-	mutex_lock(&smcd_dev_list.mutex);
-	list_del_init(&smcd->list);
-	mutex_unlock(&smcd_dev_list.mutex);
-	kfree(smcd->conn);
-	kfree(smcd);
-}
-
-static int smc_lo_dev_init(struct smc_lo_dev *ldev)
-{
-	smc_lo_generate_ids(ldev);
-	rwlock_init(&ldev->dmb_ht_lock);
-	hash_init(ldev->dmb_ht);
-	atomic_set(&ldev->dmb_cnt, 0);
-	init_waitqueue_head(&ldev->ldev_release);
-
-	return smcd_lo_register_dev(ldev);
-}
-
-static void smc_lo_dev_exit(struct smc_lo_dev *ldev)
-{
-	smcd_lo_unregister_dev(ldev);
-	if (atomic_read(&ldev->dmb_cnt))
-		wait_event(ldev->ldev_release, !atomic_read(&ldev->dmb_cnt));
-}
-
-static void smc_lo_dev_release(struct device *dev)
-{
-	struct smc_lo_dev *ldev =
-		container_of(dev, struct smc_lo_dev, dev);
-
-	kfree(ldev);
-}
-
-static int smc_lo_dev_probe(void)
-{
-	struct smc_lo_dev *ldev;
-	int ret;
-
-	ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
-	if (!ldev)
-		return -ENOMEM;
-
-	ldev->dev.parent = NULL;
-	ldev->dev.release = smc_lo_dev_release;
-	device_initialize(&ldev->dev);
-	dev_set_name(&ldev->dev, smc_lo_dev_name);
-
-	ret = smc_lo_dev_init(ldev);
-	if (ret)
-		goto free_dev;
-
-	lo_dev = ldev; /* global loopback device */
-	return 0;
-
-free_dev:
-	put_device(&ldev->dev);
-	return ret;
-}
-
-static void smc_lo_dev_remove(void)
-{
-	if (!lo_dev)
-		return;
-
-	smc_lo_dev_exit(lo_dev);
-	put_device(&lo_dev->dev); /* device_initialize in smc_lo_dev_probe */
-}
-
-int smc_loopback_init(void)
-{
-	return smc_lo_dev_probe();
-}
-
-void smc_loopback_exit(void)
-{
-	smc_lo_dev_remove();
-}

net/smc/smc_loopback.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- *  Shared Memory Communications Direct over loopback-ism device.
- *
- *  SMC-D loopback-ism device structure definitions.
- *
- *  Copyright (c) 2024, Alibaba Inc.
- *
- *  Author: Wen Gu <[e-mail]>
- *          Tony Lu <[e-mail]>
- *
- */
-
-#ifndef _SMC_LOOPBACK_H
-#define _SMC_LOOPBACK_H
-
-#include <linux/device.h>
-#include <net/smc.h>
-
-#if IS_ENABLED(CONFIG_SMC_LO)
-#define SMC_LO_MAX_DMBS		5000
-#define SMC_LO_DMBS_HASH_BITS	12
-#define SMC_LO_RESERVED_CHID	0xFFFF
-
-struct smc_lo_dmb_node {
-	struct hlist_node list;
-	u64 token;
-	u32 len;
-	u32 sba_idx;
-	void *cpu_addr;
-	dma_addr_t dma_addr;
-	refcount_t refcnt;
-};
-
-struct smc_lo_dev {
-	struct smcd_dev *smcd;
-	struct device dev;
-	u16 chid;
-	struct smcd_gid local_gid;
-	atomic_t dmb_cnt;
-	rwlock_t dmb_ht_lock;
-	DECLARE_BITMAP(sba_idx_mask, SMC_LO_MAX_DMBS);
-	DECLARE_HASHTABLE(dmb_ht, SMC_LO_DMBS_HASH_BITS);
-	wait_queue_head_t ldev_release;
-};
-
-int smc_loopback_init(void);
-void smc_loopback_exit(void);
-#else
-static inline int smc_loopback_init(void)
-{
-	return 0;
-}
-
-static inline void smc_loopback_exit(void)
-{
-}
-#endif
-
-#endif /* _SMC_LOOPBACK_H */

net/smc/smc_pnet.c

···
 			pr_warn_ratelimited("smc: smcd device %s "
 					    "erased user defined pnetid "
 					    "%.16s\n",
-					    dev_name(smcd->ops->get_dev(smcd)),
+					    dev_name(&smcd->dibs->dev),
 					    smcd->pnetid);
 			memset(smcd->pnetid, 0, SMC_MAX_PNETID_LEN);
 			smcd->pnetid_by_user = false;
···
 
 	mutex_lock(&smcd_dev_list.mutex);
 	list_for_each_entry(smcd_dev, &smcd_dev_list.list, list) {
-		if (!strncmp(dev_name(smcd_dev->ops->get_dev(smcd_dev)),
-			     smcd_name, IB_DEVICE_NAME_MAX - 1))
+		if (!strncmp(dev_name(&smcd_dev->dibs->dev), smcd_name,
+			     IB_DEVICE_NAME_MAX - 1) ||
+		    (smcd_dev->dibs->dev.parent &&
+		     !strncmp(dev_name(smcd_dev->dibs->dev.parent), smcd_name,
+			      IB_DEVICE_NAME_MAX - 1)))
 			goto out;
 	}
 	smcd_dev = NULL;
···
 	bool smcddev_applied = true;
 	bool ibdev_applied = true;
 	struct smcd_dev *smcd;
-	struct device *dev;
 	bool new_ibdev;
 
 	/* try to apply the pnetid to active devices */
···
 	if (smcd) {
 		smcddev_applied = smc_pnet_apply_smcd(smcd, pnet_name);
 		if (smcddev_applied) {
-			dev = smcd->ops->get_dev(smcd);
-			pr_warn_ratelimited("smc: smcd device %s "
-					    "applied user defined pnetid "
-					    "%.16s\n", dev_name(dev),
+			pr_warn_ratelimited("smc: smcd device %s applied user defined pnetid %.16s\n",
+					    dev_name(&smcd->dibs->dev),
 					    smcd->pnetid);
 		}
 	}
···
  */
 int smc_pnetid_by_table_smcd(struct smcd_dev *smcddev)
 {
-	const char *ib_name = dev_name(smcddev->ops->get_dev(smcddev));
 	struct smc_pnettable *pnettable;
 	struct smc_pnetentry *tmp_pe;
 	struct smc_net *sn;
···
 	mutex_lock(&pnettable->lock);
 	list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
 		if (tmp_pe->type == SMC_PNET_IB &&
-		    !strncmp(tmp_pe->ib_name, ib_name, IB_DEVICE_NAME_MAX)) {
+		    (!strncmp(tmp_pe->ib_name,
+			       dev_name(&smcddev->dibs->dev),
+			       sizeof(tmp_pe->ib_name)) ||
+		     (smcddev->dibs->dev.parent &&
+		      !strncmp(tmp_pe->ib_name,
+			       dev_name(smcddev->dibs->dev.parent),
+			       sizeof(tmp_pe->ib_name))))) {
 			smc_pnet_apply_smcd(smcddev, tmp_pe->pnet_name);
 			rc = 0;
 			break;

net/smc/smc_tx.c

···
 	int srcchunk, dstchunk;
 	int rc;
 
+	if (conn->sndbuf_desc->is_attached)
+		return 0;
+
 	for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 		for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 			void *data = conn->sndbuf_desc->cpu_addr + src_off;