[PATCH 6/8] dax: plumb hotplug online_type through dax

[Gregory Price]

There is no way for drivers leveraging dax_kmem to plumb through a
preferred auto-online policy - the system default policy is forced.

Add 'enum mmop' field to DAX device creation path to allow drivers
to specify an auto-online policy when using the kmem driver.

Current callers initialize online_type to mhp_get_default_online_type()
to retain backward compatibility and to make explicit to the drivers
what is actually happening underneath.

No functional changes to existing callers.

Cc:David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
---
 drivers/dax/bus.c         |  3 +++
 drivers/dax/bus.h         |  2 ++
 drivers/dax/cxl.c         |  1 +
 drivers/dax/dax-private.h |  3 +++
 drivers/dax/hmem/hmem.c   |  1 +
 drivers/dax/kmem.c        | 13 +++++++++++--
 6 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index c94c09622516..2c6140dc9382 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
 #include <linux/memremap.h>
+#include <linux/memory_hotplug.h>
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
@@ -395,6 +396,7 @@ static ssize_t create_store(struct device *dev, struct device_attribute *attr,
 			.size = 0,
 			.id = -1,
 			.memmap_on_memory = false,
+			.online_type = mhp_get_default_online_type(),
 		};
 		struct dev_dax *dev_dax = __devm_create_dev_dax(&data);
 
@@ -1494,6 +1496,7 @@ static struct dev_dax *__devm_create_dev_dax(struct dev_dax_data *data)
 	ida_init(&dev_dax->ida);
 
 	dev_dax->memmap_on_memory = data->memmap_on_memory;
+	dev_dax->online_type = data->online_type;
 
 	inode = dax_inode(dax_dev);
 	dev->devt = inode->i_rdev;
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index cbbf64443098..f037cd8a2d51 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -3,6 +3,7 @@
 #ifndef __DAX_BUS_H__
 #define __DAX_BUS_H__
 #include <linux/device.h>
+#include <linux/memory_hotplug.h>
 #include <linux/range.h>
 
 struct dev_dax;
@@ -24,6 +25,7 @@ struct dev_dax_data {
 	resource_size_t size;
 	int id;
 	bool memmap_on_memory;
+	enum mmop online_type;
 };
 
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index 13cd94d32ff7..d6fbec863361 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -27,6 +27,7 @@ static int cxl_dax_region_probe(struct device *dev)
 		.id = -1,
 		.size = range_len(&cxlr_dax->hpa_range),
 		.memmap_on_memory = true,
+		.online_type = mhp_get_default_online_type(),
 	};
 
 	return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index c6ae27c982f4..734fb83f5eb4 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -8,6 +8,7 @@
 #include <linux/device.h>
 #include <linux/cdev.h>
 #include <linux/idr.h>
+#include <linux/memory_hotplug.h>
 
 /* private routines between core files */
 struct dax_device;
@@ -77,6 +78,7 @@ struct dev_dax_range {
  * @dev: device core
  * @pgmap: pgmap for memmap setup / lifetime (driver owned)
  * @memmap_on_memory: allow kmem to put the memmap in the memory
+ * @online_type: MMOP_* online type for memory hotplug
  * @nr_range: size of @ranges
  * @ranges: range tuples of memory used
  */
@@ -91,6 +93,7 @@ struct dev_dax {
 	struct device dev;
 	struct dev_pagemap *pgmap;
 	bool memmap_on_memory;
+	enum mmop online_type;
 	int nr_range;
 	struct dev_dax_range *ranges;
 };
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 1cf7c2a0ee1c..acbc574ced93 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -36,6 +36,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
 		.id = -1,
 		.size = region_idle ? 0 : range_len(&mri->range),
 		.memmap_on_memory = false,
+		.online_type = mhp_get_default_online_type(),
 	};
 
 	return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 798f389df992..d4c34b2e3766 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -16,6 +16,11 @@
 #include "dax-private.h"
 #include "bus.h"
 
+/* Internal function exported only to kmem module */
+extern int __add_memory_driver_managed(int nid, u64 start, u64 size,
+				       const char *resource_name,
+				       mhp_t mhp_flags, enum mmop online_type);
+
 /* Memory resource name used for add_memory_driver_managed(). */
 static const char *kmem_name;
 /* Set if any memory will remain added when the driver will be unloaded. */
@@ -49,6 +54,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 	struct dax_kmem_data *data;
 	struct memory_dev_type *mtype;
 	int i, rc, mapped = 0;
+	enum mmop online_type;
 	mhp_t mhp_flags;
 	int numa_node;
 	int adist = MEMTIER_DEFAULT_LOWTIER_ADISTANCE;
@@ -111,6 +117,8 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		goto err_reg_mgid;
 	data->mgid = rc;
 
+	online_type = dev_dax->online_type;
+
 	for (i = 0; i < dev_dax->nr_range; i++) {
 		struct resource *res;
 		struct range range;
@@ -151,8 +159,9 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		 * Ensure that future kexec'd kernels will not treat
 		 * this as RAM automatically.
 		 */
-		rc = add_memory_driver_managed(data->mgid, range.start,
-				range_len(&range), kmem_name, mhp_flags);
+		rc = __add_memory_driver_managed(data->mgid, range.start,
+				range_len(&range), kmem_name, mhp_flags,
+				online_type);
 
 		if (rc) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
-- 
2.53.0