misc: mic: SCIF fence

This patch implements the fence APIs required to synchronize
DMAs. SCIF provides an interface to return a "mark" for all DMAs
programmed at the instant the API was called. Users can then "wait" on
the mark provided previously by blocking inside the kernel. Upon
receipt of a DMA completion interrupt the waiting thread is woken
up. There is also an interface to signal DMA completion by polling for
a location to be updated via a "signal" cookie to avoid the interrupt
overhead in the mark/wait interface. SCIF allows programming fences on
both the local and the remote node for both the mark/wait or the fence
signal APIs.
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com>
Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mic/scif/scif_fence.c

+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * Intel SCIF driver.
+ *
+ */
+
+#include "scif_main.h"
+
+/**
+ * scif_recv_mark: Handle SCIF_MARK request
+ * @msg:	Interrupt message
+ *
+ * The peer has requested a mark.
+ */
+void scif_recv_mark(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	int mark, err;
+
+	err = _scif_fence_mark(ep, &mark);
+	if (err)
+		msg->uop = SCIF_MARK_NACK;
+	else
+		msg->uop = SCIF_MARK_ACK;
+	msg->payload[0] = ep->remote_ep;
+	msg->payload[2] = mark;
+	scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_mark_resp: Handle SCIF_MARK_(N)ACK messages.
+ * @msg:	Interrupt message
+ *
+ * The peer has responded to a SCIF_MARK message.
+ */
+void scif_recv_mark_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	struct scif_fence_info *fence_req =
+		(struct scif_fence_info *)msg->payload[1];
+
+	mutex_lock(&ep->rma_info.rma_lock);
+	if (msg->uop == SCIF_MARK_ACK) {
+		fence_req->state = OP_COMPLETED;
+		fence_req->dma_mark = (int)msg->payload[2];
+	} else {
+		fence_req->state = OP_FAILED;
+	}
+	mutex_unlock(&ep->rma_info.rma_lock);
+	complete(&fence_req->comp);
+}
+
+/**
+ * scif_recv_wait: Handle SCIF_WAIT request
+ * @msg:	Interrupt message
+ *
+ * The peer has requested waiting on a fence.
+ */
+void scif_recv_wait(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	struct scif_remote_fence_info *fence;
+
+	/*
+	 * Allocate structure for remote fence information and
+	 * send a NACK if the allocation failed. The peer will
+	 * return ENOMEM upon receiving a NACK.
+	 */
+	fence = kmalloc(sizeof(*fence), GFP_KERNEL);
+	if (!fence) {
+		msg->payload[0] = ep->remote_ep;
+		msg->uop = SCIF_WAIT_NACK;
+		scif_nodeqp_send(ep->remote_dev, msg);
+		return;
+	}
+
+	/* Prepare the fence request */
+	memcpy(&fence->msg, msg, sizeof(struct scifmsg));
+	INIT_LIST_HEAD(&fence->list);
+
+	/* Insert to the global remote fence request list */
+	mutex_lock(&scif_info.fencelock);
+	atomic_inc(&ep->rma_info.fence_refcount);
+	list_add_tail(&fence->list, &scif_info.fence);
+	mutex_unlock(&scif_info.fencelock);
+
+	schedule_work(&scif_info.misc_work);
+}
+
+/**
+ * scif_recv_wait_resp: Handle SCIF_WAIT_(N)ACK messages.
+ * @msg:	Interrupt message
+ *
+ * The peer has responded to a SCIF_WAIT message.
+ */
+void scif_recv_wait_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	struct scif_fence_info *fence_req =
+		(struct scif_fence_info *)msg->payload[1];
+
+	mutex_lock(&ep->rma_info.rma_lock);
+	if (msg->uop == SCIF_WAIT_ACK)
+		fence_req->state = OP_COMPLETED;
+	else
+		fence_req->state = OP_FAILED;
+	mutex_unlock(&ep->rma_info.rma_lock);
+	complete(&fence_req->comp);
+}
+
+/**
+ * scif_recv_sig_local: Handle SCIF_SIG_LOCAL request
+ * @msg:	Interrupt message
+ *
+ * The peer has requested a signal on a local offset.
+ */
+void scif_recv_sig_local(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	int err;
+
+	err = scif_prog_signal(ep, msg->payload[1], msg->payload[2],
+			       SCIF_WINDOW_SELF);
+	if (err)
+		msg->uop = SCIF_SIG_NACK;
+	else
+		msg->uop = SCIF_SIG_ACK;
+	msg->payload[0] = ep->remote_ep;
+	scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_sig_remote: Handle SCIF_SIGNAL_REMOTE request
+ * @msg:	Interrupt message
+ *
+ * The peer has requested a signal on a remote offset.
+ */
+void scif_recv_sig_remote(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	int err;
+
+	err = scif_prog_signal(ep, msg->payload[1], msg->payload[2],
+			       SCIF_WINDOW_PEER);
+	if (err)
+		msg->uop = SCIF_SIG_NACK;
+	else
+		msg->uop = SCIF_SIG_ACK;
+	msg->payload[0] = ep->remote_ep;
+	scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_sig_resp: Handle SCIF_SIG_(N)ACK messages.
+ * @msg:	Interrupt message
+ *
+ * The peer has responded to a signal request.
+ */
+void scif_recv_sig_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+	struct scif_fence_info *fence_req =
+		(struct scif_fence_info *)msg->payload[3];
+
+	mutex_lock(&ep->rma_info.rma_lock);
+	if (msg->uop == SCIF_SIG_ACK)
+		fence_req->state = OP_COMPLETED;
+	else
+		fence_req->state = OP_FAILED;
+	mutex_unlock(&ep->rma_info.rma_lock);
+	complete(&fence_req->comp);
+}
+
+static inline void *scif_get_local_va(off_t off, struct scif_window *window)
+{
+	struct page **pages = window->pinned_pages->pages;
+	int page_nr = (off - window->offset) >> PAGE_SHIFT;
+	off_t page_off = off & ~PAGE_MASK;
+
+	return page_address(pages[page_nr]) + page_off;
+}
+
+static void scif_prog_signal_cb(void *arg)
+{
+	struct scif_status *status = arg;
+
+	dma_pool_free(status->ep->remote_dev->signal_pool, status,
+		      status->src_dma_addr);
+}
+
+static int _scif_prog_signal(scif_epd_t epd, dma_addr_t dst, u64 val)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	struct dma_chan *chan = ep->rma_info.dma_chan;
+	struct dma_device *ddev = chan->device;
+	bool x100 = !is_dma_copy_aligned(chan->device, 1, 1, 1);
+	struct dma_async_tx_descriptor *tx;
+	struct scif_status *status = NULL;
+	dma_addr_t src;
+	dma_cookie_t cookie;
+	int err;
+
+	tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, DMA_PREP_FENCE);
+	if (!tx) {
+		err = -ENOMEM;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto alloc_fail;
+	}
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		err = (int)cookie;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto alloc_fail;
+	}
+	dma_async_issue_pending(chan);
+	if (x100) {
+		/*
+		 * For X100 use the status descriptor to write the value to
+		 * the destination.
+		 */
+		tx = ddev->device_prep_dma_imm_data(chan, dst, val, 0);
+	} else {
+		status = dma_pool_alloc(ep->remote_dev->signal_pool, GFP_KERNEL,
+					&src);
+		if (!status) {
+			err = -ENOMEM;
+			dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+				__func__, __LINE__, err);
+			goto alloc_fail;
+		}
+		status->val = val;
+		status->src_dma_addr = src;
+		status->ep = ep;
+		src += offsetof(struct scif_status, val);
+		tx = ddev->device_prep_dma_memcpy(chan, dst, src, sizeof(val),
+						  DMA_PREP_INTERRUPT);
+	}
+	if (!tx) {
+		err = -ENOMEM;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto dma_fail;
+	}
+	if (!x100) {
+		tx->callback = scif_prog_signal_cb;
+		tx->callback_param = status;
+	}
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		err = -EIO;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto dma_fail;
+	}
+	dma_async_issue_pending(chan);
+	return 0;
+dma_fail:
+	if (!x100)
+		dma_pool_free(ep->remote_dev->signal_pool, status,
+			      status->src_dma_addr);
+alloc_fail:
+	return err;
+}
+
+/*
+ * scif_prog_signal:
+ * @epd - Endpoint Descriptor
+ * @offset - registered address to write @val to
+ * @val - Value to be written at @offset
+ * @type - Type of the window.
+ *
+ * Arrange to write a value to the registered offset after ensuring that the
+ * offset provided is indeed valid.
+ */
+int scif_prog_signal(scif_epd_t epd, off_t offset, u64 val,
+		     enum scif_window_type type)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	struct scif_window *window = NULL;
+	struct scif_rma_req req;
+	dma_addr_t dst_dma_addr;
+	int err;
+
+	mutex_lock(&ep->rma_info.rma_lock);
+	req.out_window = &window;
+	req.offset = offset;
+	req.nr_bytes = sizeof(u64);
+	req.prot = SCIF_PROT_WRITE;
+	req.type = SCIF_WINDOW_SINGLE;
+	if (type == SCIF_WINDOW_SELF)
+		req.head = &ep->rma_info.reg_list;
+	else
+		req.head = &ep->rma_info.remote_reg_list;
+	/* Does a valid window exist? */
+	err = scif_query_window(&req);
+	if (err) {
+		dev_err(scif_info.mdev.this_device,
+			"%s %d err %d\n", __func__, __LINE__, err);
+		goto unlock_ret;
+	}
+
+	if (scif_is_mgmt_node() && scifdev_self(ep->remote_dev)) {
+		u64 *dst_virt;
+
+		if (type == SCIF_WINDOW_SELF)
+			dst_virt = scif_get_local_va(offset, window);
+		else
+			dst_virt =
+			scif_get_local_va(offset, (struct scif_window *)
+					  window->peer_window);
+		*dst_virt = val;
+	} else {
+		dst_dma_addr = __scif_off_to_dma_addr(window, offset);
+		err = _scif_prog_signal(epd, dst_dma_addr, val);
+	}
+unlock_ret:
+	mutex_unlock(&ep->rma_info.rma_lock);
+	return err;
+}
+
+static int _scif_fence_wait(scif_epd_t epd, int mark)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	dma_cookie_t cookie = mark & ~SCIF_REMOTE_FENCE;
+	int err;
+
+	/* Wait for DMA callback in scif_fence_mark_cb(..) */
+	err = wait_event_interruptible_timeout(ep->rma_info.markwq,
+					       dma_async_is_tx_complete(
+					       ep->rma_info.dma_chan,
+					       cookie, NULL, NULL) ==
+					       DMA_COMPLETE,
+					       SCIF_NODE_ALIVE_TIMEOUT);
+	if (!err)
+		err = -ETIMEDOUT;
+	else if (err > 0)
+		err = 0;
+	return err;
+}
+
+/**
+ * scif_rma_handle_remote_fences:
+ *
+ * This routine services remote fence requests.
+ */
+void scif_rma_handle_remote_fences(void)
+{
+	struct list_head *item, *tmp;
+	struct scif_remote_fence_info *fence;
+	struct scif_endpt *ep;
+	int mark, err;
+
+	might_sleep();
+	mutex_lock(&scif_info.fencelock);
+	list_for_each_safe(item, tmp, &scif_info.fence) {
+		fence = list_entry(item, struct scif_remote_fence_info,
+				   list);
+		/* Remove fence from global list */
+		list_del(&fence->list);
+
+		/* Initiate the fence operation */
+		ep = (struct scif_endpt *)fence->msg.payload[0];
+		mark = fence->msg.payload[2];
+		err = _scif_fence_wait(ep, mark);
+		if (err)
+			fence->msg.uop = SCIF_WAIT_NACK;
+		else
+			fence->msg.uop = SCIF_WAIT_ACK;
+		fence->msg.payload[0] = ep->remote_ep;
+		scif_nodeqp_send(ep->remote_dev, &fence->msg);
+		kfree(fence);
+		if (!atomic_sub_return(1, &ep->rma_info.fence_refcount))
+			schedule_work(&scif_info.misc_work);
+	}
+	mutex_unlock(&scif_info.fencelock);
+}
+
+static int _scif_send_fence(scif_epd_t epd, int uop, int mark, int *out_mark)
+{
+	int err;
+	struct scifmsg msg;
+	struct scif_fence_info *fence_req;
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+
+	fence_req = kmalloc(sizeof(*fence_req), GFP_KERNEL);
+	if (!fence_req) {
+		err = -ENOMEM;
+		goto error;
+	}
+
+	fence_req->state = OP_IN_PROGRESS;
+	init_completion(&fence_req->comp);
+
+	msg.src = ep->port;
+	msg.uop = uop;
+	msg.payload[0] = ep->remote_ep;
+	msg.payload[1] = (u64)fence_req;
+	if (uop == SCIF_WAIT)
+		msg.payload[2] = mark;
+	spin_lock(&ep->lock);
+	if (ep->state == SCIFEP_CONNECTED)
+		err = scif_nodeqp_send(ep->remote_dev, &msg);
+	else
+		err = -ENOTCONN;
+	spin_unlock(&ep->lock);
+	if (err)
+		goto error_free;
+retry:
+	/* Wait for a SCIF_WAIT_(N)ACK message */
+	err = wait_for_completion_timeout(&fence_req->comp,
+					  SCIF_NODE_ALIVE_TIMEOUT);
+	if (!err && scifdev_alive(ep))
+		goto retry;
+	if (!err)
+		err = -ENODEV;
+	if (err > 0)
+		err = 0;
+	mutex_lock(&ep->rma_info.rma_lock);
+	if (err < 0) {
+		if (fence_req->state == OP_IN_PROGRESS)
+			fence_req->state = OP_FAILED;
+	}
+	if (fence_req->state == OP_FAILED && !err)
+		err = -ENOMEM;
+	if (uop == SCIF_MARK && fence_req->state == OP_COMPLETED)
+		*out_mark = SCIF_REMOTE_FENCE | fence_req->dma_mark;
+	mutex_unlock(&ep->rma_info.rma_lock);
+error_free:
+	kfree(fence_req);
+error:
+	return err;
+}
+
+/**
+ * scif_send_fence_mark:
+ * @epd: end point descriptor.
+ * @out_mark: Output DMA mark reported by peer.
+ *
+ * Send a remote fence mark request.
+ */
+static int scif_send_fence_mark(scif_epd_t epd, int *out_mark)
+{
+	return _scif_send_fence(epd, SCIF_MARK, 0, out_mark);
+}
+
+/**
+ * scif_send_fence_wait:
+ * @epd: end point descriptor.
+ * @mark: DMA mark to wait for.
+ *
+ * Send a remote fence wait request.
+ */
+static int scif_send_fence_wait(scif_epd_t epd, int mark)
+{
+	return _scif_send_fence(epd, SCIF_WAIT, mark, NULL);
+}
+
+static int _scif_send_fence_signal_wait(struct scif_endpt *ep,
+					struct scif_fence_info *fence_req)
+{
+	int err;
+
+retry:
+	/* Wait for a SCIF_SIG_(N)ACK message */
+	err = wait_for_completion_timeout(&fence_req->comp,
+					  SCIF_NODE_ALIVE_TIMEOUT);
+	if (!err && scifdev_alive(ep))
+		goto retry;
+	if (!err)
+		err = -ENODEV;
+	if (err > 0)
+		err = 0;
+	if (err < 0) {
+		mutex_lock(&ep->rma_info.rma_lock);
+		if (fence_req->state == OP_IN_PROGRESS)
+			fence_req->state = OP_FAILED;
+		mutex_unlock(&ep->rma_info.rma_lock);
+	}
+	if (fence_req->state == OP_FAILED && !err)
+		err = -ENXIO;
+	return err;
+}
+
+/**
+ * scif_send_fence_signal:
+ * @epd - endpoint descriptor
+ * @loff - local offset
+ * @lval - local value to write to loffset
+ * @roff - remote offset
+ * @rval - remote value to write to roffset
+ * @flags - flags
+ *
+ * Sends a remote fence signal request
+ */
+static int scif_send_fence_signal(scif_epd_t epd, off_t roff, u64 rval,
+				  off_t loff, u64 lval, int flags)
+{
+	int err = 0;
+	struct scifmsg msg;
+	struct scif_fence_info *fence_req;
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+
+	fence_req = kmalloc(sizeof(*fence_req), GFP_KERNEL);
+	if (!fence_req) {
+		err = -ENOMEM;
+		goto error;
+	}
+
+	fence_req->state = OP_IN_PROGRESS;
+	init_completion(&fence_req->comp);
+	msg.src = ep->port;
+	if (flags & SCIF_SIGNAL_LOCAL) {
+		msg.uop = SCIF_SIG_LOCAL;
+		msg.payload[0] = ep->remote_ep;
+		msg.payload[1] = roff;
+		msg.payload[2] = rval;
+		msg.payload[3] = (u64)fence_req;
+		spin_lock(&ep->lock);
+		if (ep->state == SCIFEP_CONNECTED)
+			err = scif_nodeqp_send(ep->remote_dev, &msg);
+		else
+			err = -ENOTCONN;
+		spin_unlock(&ep->lock);
+		if (err)
+			goto error_free;
+		err = _scif_send_fence_signal_wait(ep, fence_req);
+		if (err)
+			goto error_free;
+	}
+	fence_req->state = OP_IN_PROGRESS;
+
+	if (flags & SCIF_SIGNAL_REMOTE) {
+		msg.uop = SCIF_SIG_REMOTE;
+		msg.payload[0] = ep->remote_ep;
+		msg.payload[1] = loff;
+		msg.payload[2] = lval;
+		msg.payload[3] = (u64)fence_req;
+		spin_lock(&ep->lock);
+		if (ep->state == SCIFEP_CONNECTED)
+			err = scif_nodeqp_send(ep->remote_dev, &msg);
+		else
+			err = -ENOTCONN;
+		spin_unlock(&ep->lock);
+		if (err)
+			goto error_free;
+		err = _scif_send_fence_signal_wait(ep, fence_req);
+	}
+error_free:
+	kfree(fence_req);
+error:
+	return err;
+}
+
+static void scif_fence_mark_cb(void *arg)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)arg;
+
+	wake_up_interruptible(&ep->rma_info.markwq);
+	atomic_dec(&ep->rma_info.fence_refcount);
+}
+
+/*
+ * _scif_fence_mark:
+ *
+ * @epd - endpoint descriptor
+ * Set up a mark for this endpoint and return the value of the mark.
+ */
+int _scif_fence_mark(scif_epd_t epd, int *mark)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	struct dma_chan *chan = ep->rma_info.dma_chan;
+	struct dma_device *ddev = chan->device;
+	struct dma_async_tx_descriptor *tx;
+	dma_cookie_t cookie;
+	int err;
+
+	tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, DMA_PREP_FENCE);
+	if (!tx) {
+		err = -ENOMEM;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		return err;
+	}
+	cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		err = (int)cookie;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		return err;
+	}
+	dma_async_issue_pending(chan);
+	tx = ddev->device_prep_dma_interrupt(chan, DMA_PREP_INTERRUPT);
+	if (!tx) {
+		err = -ENOMEM;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		return err;
+	}
+	tx->callback = scif_fence_mark_cb;
+	tx->callback_param = ep;
+	*mark = cookie = tx->tx_submit(tx);
+	if (dma_submit_error(cookie)) {
+		err = (int)cookie;
+		dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+			__func__, __LINE__, err);
+		return err;
+	}
+	atomic_inc(&ep->rma_info.fence_refcount);
+	dma_async_issue_pending(chan);
+	return 0;
+}
+
+#define SCIF_LOOPB_MAGIC_MARK 0xdead
+
+int scif_fence_mark(scif_epd_t epd, int flags, int *mark)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	int err = 0;
+
+	dev_dbg(scif_info.mdev.this_device,
+		"SCIFAPI fence_mark: ep %p flags 0x%x mark 0x%x\n",
+		ep, flags, *mark);
+	err = scif_verify_epd(ep);
+	if (err)
+		return err;
+
+	/* Invalid flags? */
+	if (flags & ~(SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER))
+		return -EINVAL;
+
+	/* At least one of init self or peer RMA should be set */
+	if (!(flags & (SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER)))
+		return -EINVAL;
+
+	/* Exactly one of init self or peer RMA should be set but not both */
+	if ((flags & SCIF_FENCE_INIT_SELF) && (flags & SCIF_FENCE_INIT_PEER))
+		return -EINVAL;
+
+	/*
+	 * Management node loopback does not need to use DMA.
+	 * Return a valid mark to be symmetric.
+	 */
+	if (scifdev_self(ep->remote_dev) && scif_is_mgmt_node()) {
+		*mark = SCIF_LOOPB_MAGIC_MARK;
+		return 0;
+	}
+
+	if (flags & SCIF_FENCE_INIT_SELF)
+		err = _scif_fence_mark(epd, mark);
+	else
+		err = scif_send_fence_mark(ep, mark);
+
+	if (err)
+		dev_err(scif_info.mdev.this_device,
+			"%s %d err %d\n", __func__, __LINE__, err);
+	dev_dbg(scif_info.mdev.this_device,
+		"SCIFAPI fence_mark: ep %p flags 0x%x mark 0x%x err %d\n",
+		ep, flags, *mark, err);
+	return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_mark);
+
+int scif_fence_wait(scif_epd_t epd, int mark)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	int err = 0;
+
+	dev_dbg(scif_info.mdev.this_device,
+		"SCIFAPI fence_wait: ep %p mark 0x%x\n",
+		ep, mark);
+	err = scif_verify_epd(ep);
+	if (err)
+		return err;
+	/*
+	 * Management node loopback does not need to use DMA.
+	 * The only valid mark provided is 0 so simply
+	 * return success if the mark is valid.
+	 */
+	if (scifdev_self(ep->remote_dev) && scif_is_mgmt_node()) {
+		if (mark == SCIF_LOOPB_MAGIC_MARK)
+			return 0;
+		else
+			return -EINVAL;
+	}
+	if (mark & SCIF_REMOTE_FENCE)
+		err = scif_send_fence_wait(epd, mark);
+	else
+		err = _scif_fence_wait(epd, mark);
+	if (err < 0)
+		dev_err(scif_info.mdev.this_device,
+			"%s %d err %d\n", __func__, __LINE__, err);
+	return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_wait);
+
+int scif_fence_signal(scif_epd_t epd, off_t loff, u64 lval,
+		      off_t roff, u64 rval, int flags)
+{
+	struct scif_endpt *ep = (struct scif_endpt *)epd;
+	int err = 0;
+
+	dev_dbg(scif_info.mdev.this_device,
+		"SCIFAPI fence_signal: ep %p loff 0x%lx lval 0x%llx roff 0x%lx rval 0x%llx flags 0x%x\n",
+		ep, loff, lval, roff, rval, flags);
+	err = scif_verify_epd(ep);
+	if (err)
+		return err;
+
+	/* Invalid flags? */
+	if (flags & ~(SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER |
+			SCIF_SIGNAL_LOCAL | SCIF_SIGNAL_REMOTE))
+		return -EINVAL;
+
+	/* At least one of init self or peer RMA should be set */
+	if (!(flags & (SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER)))
+		return -EINVAL;
+
+	/* Exactly one of init self or peer RMA should be set but not both */
+	if ((flags & SCIF_FENCE_INIT_SELF) && (flags & SCIF_FENCE_INIT_PEER))
+		return -EINVAL;
+
+	/* At least one of SCIF_SIGNAL_LOCAL or SCIF_SIGNAL_REMOTE required */
+	if (!(flags & (SCIF_SIGNAL_LOCAL | SCIF_SIGNAL_REMOTE)))
+		return -EINVAL;
+
+	/* Only Dword offsets allowed */
+	if ((flags & SCIF_SIGNAL_LOCAL) && (loff & (sizeof(u32) - 1)))
+		return -EINVAL;
+
+	/* Only Dword aligned offsets allowed */
+	if ((flags & SCIF_SIGNAL_REMOTE) && (roff & (sizeof(u32) - 1)))
+		return -EINVAL;
+
+	if (flags & SCIF_FENCE_INIT_PEER) {
+		err = scif_send_fence_signal(epd, roff, rval, loff,
+					     lval, flags);
+	} else {
+		/* Local Signal in Local RAS */
+		if (flags & SCIF_SIGNAL_LOCAL) {
+			err = scif_prog_signal(epd, loff, lval,
+					       SCIF_WINDOW_SELF);
+			if (err)
+				goto error_ret;
+		}
+
+		/* Signal in Remote RAS */
+		if (flags & SCIF_SIGNAL_REMOTE)
+			err = scif_prog_signal(epd, roff,
+					       rval, SCIF_WINDOW_PEER);
+	}
+error_ret:
+	if (err)
+		dev_err(scif_info.mdev.this_device,
+			"%s %d err %d\n", __func__, __LINE__, err);
+	return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_signal);