Soft RoCE driver

Soft RoCE (RXE) - The software RoCE driver

ib_rxe implements the RDMA transport and registers to the RDMA core
device as a kernel verbs provider. It also implements the packet IO
layer. On the other hand ib_rxe registers to the Linux netdev stack
as a udp encapsulating protocol, in that case RDMA, for sending and
receiving packets over any Ethernet device.  This yields a RDMA
transport over the UDP/Ethernet network layer forming a RoCEv2
compatible device.

The configuration procedure of the Soft RoCE drivers requires
binding to any existing Ethernet network device. This is done with
/sys interface.

A userspace Soft RoCE library (librxe) provides user applications
the ability to run with Soft RoCE devices.  The use of rxe verbs ins
user space requires the inclusion of librxe as a device specifics
plug-in to libibverbs. librxe is packaged separately.

Architecture:

     +-----------------------------------------------------------+
     |                          Application                      |
     +-----------------------------------------------------------+
                            +-----------------------------------+
                            |             libibverbs            |
User                        +-----------------------------------+
                            +----------------+ +----------------+
                            | librxe         | | HW RoCE lib    |
                            +----------------+ +----------------+
+---------------------------------------------------------------+
     +--------------+                           +------------+
     | Sockets      |                           | RDMA ULP   |
     +--------------+                           +------------+
     +--------------+                  +---------------------+
     | TCP/IP       |                  | ib_core             |
     +--------------+                  +---------------------+
                             +------------+ +----------------+
Kernel                       | ib_rxe     | | HW RoCE driver |
                             +------------+ +----------------+
     +------------------------------------+
     | NIC driver                         |
     +------------------------------------+

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     +-----------------------------------------------------------+
     |                          Application                      |
     +-----------------------------------------------------------+
                            +-----------------------------------+
                            |             libibverbs            |
User                        +-----------------------------------+
                            +----------------+ +----------------+
                            | librxe         | | HW RoCE lib    |
                            +----------------+ +----------------+
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     +--------------+                           +------------+
     | Sockets      |                           | RDMA ULP   |
     +--------------+                           +------------+
     +--------------+                  +---------------------+
     | TCP/IP       |                  | ib_core             |
     +--------------+                  +---------------------+
                             +------------+ +----------------+
Kernel                       | ib_rxe     | | HW RoCE driver |
                             +------------+ +----------------+
     +------------------------------------+
     | NIC driver                         |
     +------------------------------------+
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Soft RoCE resources:

[1[ https://github.com/SoftRoCE/librxe-dev librxe - source code in
Github
[2] https://github.com/SoftRoCE/rxe-dev/wiki/rxe-dev:-Home - Soft RoCE
Wiki page
[3] https://github.com/SoftRoCE/librxe-dev - Soft RoCE userspace library

Signed-off-by: Kamal Heib <kamalh@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: Moni Shoua <monis@mellanox.com>
Reviewed-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 154 insertions, 0 deletions

diff --git a/drivers/infiniband/sw/rxe/rxe_task.c b/drivers/infiniband/sw/rxe/rxe_task.c
new file mode 100644
index 000000000000..1e19bf828a6e
--- /dev/null
+++ b/drivers/infiniband/sw/rxe/rxe_task.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
+ * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *	   Redistribution and use in source and binary forms, with or
+ *	   without modification, are permitted provided that the following
+ *	   conditions are met:
+ *
+ *	- Redistributions of source code must retain the above
+ *	  copyright notice, this list of conditions and the following
+ *	  disclaimer.
+ *
+ *	- Redistributions in binary form must reproduce the above
+ *	  copyright notice, this list of conditions and the following
+ *	  disclaimer in the documentation and/or other materials
+ *	  provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/hardirq.h>
+
+#include "rxe_task.h"
+
+int __rxe_do_task(struct rxe_task *task)
+
+{
+	int ret;
+
+	while ((ret = task->func(task->arg)) == 0)
+		;
+
+	task->ret = ret;
+
+	return ret;
+}
+
+/*
+ * this locking is due to a potential race where
+ * a second caller finds the task already running
+ * but looks just after the last call to func
+ */
+void rxe_do_task(unsigned long data)
+{
+	int cont;
+	int ret;
+	unsigned long flags;
+	struct rxe_task *task = (struct rxe_task *)data;
+
+	spin_lock_irqsave(&task->state_lock, flags);
+	switch (task->state) {
+	case TASK_STATE_START:
+		task->state = TASK_STATE_BUSY;
+		spin_unlock_irqrestore(&task->state_lock, flags);
+		break;
+
+	case TASK_STATE_BUSY:
+		task->state = TASK_STATE_ARMED;
+		/* fall through to */
+	case TASK_STATE_ARMED:
+		spin_unlock_irqrestore(&task->state_lock, flags);
+		return;
+
+	default:
+		spin_unlock_irqrestore(&task->state_lock, flags);
+		pr_warn("bad state = %d in rxe_do_task\n", task->state);
+		return;
+	}
+
+	do {
+		cont = 0;
+		ret = task->func(task->arg);
+
+		spin_lock_irqsave(&task->state_lock, flags);
+		switch (task->state) {
+		case TASK_STATE_BUSY:
+			if (ret)
+				task->state = TASK_STATE_START;
+			else
+				cont = 1;
+			break;
+
+		/* soneone tried to run the task since the last time we called
+		 * func, so we will call one more time regardless of the
+		 * return value
+		 */
+		case TASK_STATE_ARMED:
+			task->state = TASK_STATE_BUSY;
+			cont = 1;
+			break;
+
+		default:
+			pr_warn("bad state = %d in rxe_do_task\n",
+				task->state);
+		}
+		spin_unlock_irqrestore(&task->state_lock, flags);
+	} while (cont);
+
+	task->ret = ret;
+}
+
+int rxe_init_task(void *obj, struct rxe_task *task,
+		  void *arg, int (*func)(void *), char *name)
+{
+	task->obj	= obj;
+	task->arg	= arg;
+	task->func	= func;
+	snprintf(task->name, sizeof(task->name), "%s", name);
+
+	tasklet_init(&task->tasklet, rxe_do_task, (unsigned long)task);
+
+	task->state = TASK_STATE_START;
+	spin_lock_init(&task->state_lock);
+
+	return 0;
+}
+
+void rxe_cleanup_task(struct rxe_task *task)
+{
+	tasklet_kill(&task->tasklet);
+}
+
+void rxe_run_task(struct rxe_task *task, int sched)
+{
+	if (sched)
+		tasklet_schedule(&task->tasklet);
+	else
+		rxe_do_task((unsigned long)task);
+}
+
+void rxe_disable_task(struct rxe_task *task)
+{
+	tasklet_disable(&task->tasklet);
+}
+
+void rxe_enable_task(struct rxe_task *task)
+{
+	tasklet_enable(&task->tasklet);
+}