Merge tag 'cxl-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl

Pull Compute Express Link (CXL) updates from Dan Williams:
 "To date Linux has been dependent on platform-firmware to map CXL RAM
  regions and handle events / errors from devices. With this update we
  can now parse / update the CXL memory layout, and report events /
  errors from devices. This is a precursor for the CXL subsystem to
  handle the end-to-end "RAS" flow for CXL memory. i.e. the flow that
  for DDR-attached-DRAM is handled by the EDAC driver where it maps
  system physical address events to a field-replaceable-unit (FRU /
  endpoint device). In general, CXL has the potential to standardize
  what has historically been a pile of memory-controller-specific error
  handling logic.

  Another change of note is the default policy for handling RAM-backed
  device-dax instances. Previously the default access mode was "device",
  mmap(2) a device special file to access memory. The new default is
  "kmem" where the address range is assigned to the core-mm via
  add_memory_driver_managed(). This saves typical users from wondering
  why their platform memory is not visible via free(1) and stuck behind
  a device-file. At the same time it allows expert users to deploy
  policy to, for example, get dedicated access to high performance
  memory, or hide low performance memory from general purpose kernel
  allocations. This affects not only CXL, but also systems with
  high-bandwidth-memory that platform-firmware tags with the
  EFI_MEMORY_SP (special purpose) designation.

  Summary:

   - CXL RAM region enumeration: instantiate 'struct cxl_region' objects
     for platform firmware created memory regions

   - CXL RAM region provisioning: complement the existing PMEM region
     creation support with RAM region support

   - "Soft Reservation" policy change: Online (memory hot-add)
     soft-reserved memory (EFI_MEMORY_SP) by default, but still allow
     for setting aside such memory for dedicated access via device-dax.

   - CXL Events and Interrupts: Takeover CXL event handling from
     platform-firmware (ACPI calls this CXL Memory Error Reporting) and
     export CXL Events via Linux Trace Events.

   - Convey CXL _OSC results to drivers: Similar to PCI, let the CXL
     subsystem interrogate the result of CXL _OSC negotiation.

   - Emulate CXL DVSEC Range Registers as "decoders": Allow for
     first-generation devices that pre-date the definition of the CXL
     HDM Decoder Capability to translate the CXL DVSEC Range Registers
     into 'struct cxl_decoder' objects.

   - Set timestamp: Per spec, set the device timestamp in case of
     hotplug, or if platform-firwmare failed to set it.

   - General fixups: linux-next build issues, non-urgent fixes for
     pre-production hardware, unit test fixes, spelling and debug
     message improvements"

* tag 'cxl-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (66 commits)
  dax/kmem: Fix leak of memory-hotplug resources
  cxl/mem: Add kdoc param for event log driver state
  cxl/trace: Add serial number to trace points
  cxl/trace: Add host output to trace points
  cxl/trace: Standardize device information output
  cxl/pci: Remove locked check for dvsec_range_allowed()
  cxl/hdm: Add emulation when HDM decoders are not committed
  cxl/hdm: Create emulated cxl_hdm for devices that do not have HDM decoders
  cxl/hdm: Emulate HDM decoder from DVSEC range registers
  cxl/pci: Refactor cxl_hdm_decode_init()
  cxl/port: Export cxl_dvsec_rr_decode() to cxl_port
  cxl/pci: Break out range register decoding from cxl_hdm_decode_init()
  cxl: add RAS status unmasking for CXL
  cxl: remove unnecessary calling of pci_enable_pcie_error_reporting()
  dax/hmem: build hmem device support as module if possible
  dax: cxl: add CXL_REGION dependency
  cxl: avoid returning uninitialized error code
  cxl/pmem: Fix nvdimm registration races
  cxl/mem: Fix UAPI command comment
  cxl/uapi: Tag commands from cxl_query_cmd()
  ...

10 files changed, 284 insertions, 116 deletions

diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index 2bf5123e4827..a88744244149 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -44,12 +44,25 @@ config DEV_DAX_HMEM
 
 	  Say M if unsure.
 
+config DEV_DAX_CXL
+	tristate "CXL DAX: direct access to CXL RAM regions"
+	depends on CXL_BUS && CXL_REGION && DEV_DAX
+	default CXL_REGION && DEV_DAX
+	help
+	  CXL RAM regions are either mapped by platform-firmware
+	  and published in the initial system-memory map as "System RAM", mapped
+	  by platform-firmware as "Soft Reserved", or dynamically provisioned
+	  after boot by the CXL driver. In the latter two cases a device-dax
+	  instance is created to access that unmapped-by-default address range.
+	  Per usual it can remain as dedicated access via a device interface, or
+	  converted to "System RAM" via the dax_kmem facility.
+
 config DEV_DAX_HMEM_DEVICES
-	depends on DEV_DAX_HMEM && DAX=y
+	depends on DEV_DAX_HMEM && DAX
 	def_bool y
 
 config DEV_DAX_KMEM
-	tristate "KMEM DAX: volatile-use of persistent memory"
+	tristate "KMEM DAX: map dax-devices as System-RAM"
 	default DEV_DAX
 	depends on DEV_DAX
 	depends on MEMORY_HOTPLUG # for add_memory() and friends
diff --git a/drivers/dax/Makefile b/drivers/dax/Makefile
index 90a56ca3b345..5ed5c39857c8 100644
--- a/drivers/dax/Makefile
+++ b/drivers/dax/Makefile
@@ -3,10 +3,12 @@ obj-$(CONFIG_DAX) += dax.o
 obj-$(CONFIG_DEV_DAX) += device_dax.o
 obj-$(CONFIG_DEV_DAX_KMEM) += kmem.o
 obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
+obj-$(CONFIG_DEV_DAX_CXL) += dax_cxl.o
 
 dax-y := super.o
 dax-y += bus.o
 device_dax-y := device.o
 dax_pmem-y := pmem.o
+dax_cxl-y := cxl.o
 
 obj-y += hmem/
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index e3a384182fe7..227800053309 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -56,6 +56,25 @@ static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
 	return match;
 }
 
+static int dax_match_type(struct dax_device_driver *dax_drv, struct device *dev)
+{
+	enum dax_driver_type type = DAXDRV_DEVICE_TYPE;
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+
+	if (dev_dax->region->res.flags & IORESOURCE_DAX_KMEM)
+		type = DAXDRV_KMEM_TYPE;
+
+	if (dax_drv->type == type)
+		return 1;
+
+	/* default to device mode if dax_kmem is disabled */
+	if (dax_drv->type == DAXDRV_DEVICE_TYPE &&
+	    !IS_ENABLED(CONFIG_DEV_DAX_KMEM))
+		return 1;
+
+	return 0;
+}
+
 enum id_action {
 	ID_REMOVE,
 	ID_ADD,
@@ -216,14 +235,9 @@ static int dax_bus_match(struct device *dev, struct device_driver *drv)
 {
 	struct dax_device_driver *dax_drv = to_dax_drv(drv);
 
-	/*
-	 * All but the 'device-dax' driver, which has 'match_always'
-	 * set, requires an exact id match.
-	 */
-	if (dax_drv->match_always)
+	if (dax_match_id(dax_drv, dev))
 		return 1;
-
-	return dax_match_id(dax_drv, dev);
+	return dax_match_type(dax_drv, dev);
 }
 
 /*
@@ -427,8 +441,8 @@ static void unregister_dev_dax(void *dev)
 	dev_dbg(dev, "%s\n", __func__);
 
 	kill_dev_dax(dev_dax);
-	free_dev_dax_ranges(dev_dax);
 	device_del(dev);
+	free_dev_dax_ranges(dev_dax);
 	put_device(dev);
 }
 
@@ -1413,13 +1427,10 @@ err_id:
 }
 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 
-static int match_always_count;
-
 int __dax_driver_register(struct dax_device_driver *dax_drv,
 		struct module *module, const char *mod_name)
 {
 	struct device_driver *drv = &dax_drv->drv;
-	int rc = 0;
 
 	/*
 	 * dax_bus_probe() calls dax_drv->probe() unconditionally.
@@ -1434,26 +1445,7 @@ int __dax_driver_register(struct dax_device_driver *dax_drv,
 	drv->mod_name = mod_name;
 	drv->bus = &dax_bus_type;
 
-	/* there can only be one default driver */
-	mutex_lock(&dax_bus_lock);
-	match_always_count += dax_drv->match_always;
-	if (match_always_count > 1) {
-		match_always_count--;
-		WARN_ON(1);
-		rc = -EINVAL;
-	}
-	mutex_unlock(&dax_bus_lock);
-	if (rc)
-		return rc;
-
-	rc = driver_register(drv);
-	if (rc && dax_drv->match_always) {
-		mutex_lock(&dax_bus_lock);
-		match_always_count -= dax_drv->match_always;
-		mutex_unlock(&dax_bus_lock);
-	}
-
-	return rc;
+	return driver_register(drv);
 }
 EXPORT_SYMBOL_GPL(__dax_driver_register);
 
@@ -1463,7 +1455,6 @@ void dax_driver_unregister(struct dax_device_driver *dax_drv)
 	struct dax_id *dax_id, *_id;
 
 	mutex_lock(&dax_bus_lock);
-	match_always_count -= dax_drv->match_always;
 	list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
 		list_del(&dax_id->list);
 		kfree(dax_id);
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index fbb940293d6d..8cd79ab34292 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -11,7 +11,10 @@ struct dax_device;
 struct dax_region;
 void dax_region_put(struct dax_region *dax_region);
 
-#define IORESOURCE_DAX_STATIC (1UL << 0)
+/* dax bus specific ioresource flags */
+#define IORESOURCE_DAX_STATIC BIT(0)
+#define IORESOURCE_DAX_KMEM BIT(1)
+
 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 		struct range *range, int target_node, unsigned int align,
 		unsigned long flags);
@@ -25,10 +28,15 @@ struct dev_dax_data {
 
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
 
+enum dax_driver_type {
+	DAXDRV_KMEM_TYPE,
+	DAXDRV_DEVICE_TYPE,
+};
+
 struct dax_device_driver {
 	struct device_driver drv;
 	struct list_head ids;
-	int match_always;
+	enum dax_driver_type type;
 	int (*probe)(struct dev_dax *dev);
 	void (*remove)(struct dev_dax *dev);
 };
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
new file mode 100644
index 000000000000..ccdf8de85bd5
--- /dev/null
+++ b/drivers/dax/cxl.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+#include <linux/module.h>
+#include <linux/dax.h>
+
+#include "../cxl/cxl.h"
+#include "bus.h"
+
+static int cxl_dax_region_probe(struct device *dev)
+{
+	struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
+	int nid = phys_to_target_node(cxlr_dax->hpa_range.start);
+	struct cxl_region *cxlr = cxlr_dax->cxlr;
+	struct dax_region *dax_region;
+	struct dev_dax_data data;
+	struct dev_dax *dev_dax;
+
+	if (nid == NUMA_NO_NODE)
+		nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);
+
+	dax_region = alloc_dax_region(dev, cxlr->id, &cxlr_dax->hpa_range, nid,
+				      PMD_SIZE, IORESOURCE_DAX_KMEM);
+	if (!dax_region)
+		return -ENOMEM;
+
+	data = (struct dev_dax_data) {
+		.dax_region = dax_region,
+		.id = -1,
+		.size = range_len(&cxlr_dax->hpa_range),
+	};
+	dev_dax = devm_create_dev_dax(&data);
+	if (IS_ERR(dev_dax))
+		return PTR_ERR(dev_dax);
+
+	/* child dev_dax instances now own the lifetime of the dax_region */
+	dax_region_put(dax_region);
+	return 0;
+}
+
+static struct cxl_driver cxl_dax_region_driver = {
+	.name = "cxl_dax_region",
+	.probe = cxl_dax_region_probe,
+	.id = CXL_DEVICE_DAX_REGION,
+	.drv = {
+		.suppress_bind_attrs = true,
+	},
+};
+
+module_cxl_driver(cxl_dax_region_driver);
+MODULE_ALIAS_CXL(CXL_DEVICE_DAX_REGION);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_IMPORT_NS(CXL);
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 223e4e233d19..af9930c03c9c 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -475,8 +475,7 @@ EXPORT_SYMBOL_GPL(dev_dax_probe);
 
 static struct dax_device_driver device_dax_driver = {
 	.probe = dev_dax_probe,
-	/* all probe actions are unwound by devm, so .remove isn't necessary */
-	.match_always = 1,
+	.type = DAXDRV_DEVICE_TYPE,
 };
 
 static int __init dax_init(void)
diff --git a/drivers/dax/hmem/Makefile b/drivers/dax/hmem/Makefile
index 57377b4c3d47..d4c4cd6bccd7 100644
--- a/drivers/dax/hmem/Makefile
+++ b/drivers/dax/hmem/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_DEV_DAX_HMEM) += dax_hmem.o
+# device_hmem.o deliberately precedes dax_hmem.o for initcall ordering
 obj-$(CONFIG_DEV_DAX_HMEM_DEVICES) += device_hmem.o
+obj-$(CONFIG_DEV_DAX_HMEM) += dax_hmem.o
 
 device_hmem-y := device.o
 dax_hmem-y := hmem.o
diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c
index 903325aac991..f9e1a76a04a9 100644
--- a/drivers/dax/hmem/device.c
+++ b/drivers/dax/hmem/device.c
@@ -8,6 +8,8 @@
 static bool nohmem;
 module_param_named(disable, nohmem, bool, 0444);
 
+static bool platform_initialized;
+static DEFINE_MUTEX(hmem_resource_lock);
 static struct resource hmem_active = {
 	.name = "HMEM devices",
 	.start = 0,
@@ -15,80 +17,66 @@ static struct resource hmem_active = {
 	.flags = IORESOURCE_MEM,
 };
 
-void hmem_register_device(int target_nid, struct resource *r)
+int walk_hmem_resources(struct device *host, walk_hmem_fn fn)
+{
+	struct resource *res;
+	int rc = 0;
+
+	mutex_lock(&hmem_resource_lock);
+	for (res = hmem_active.child; res; res = res->sibling) {
+		rc = fn(host, (int) res->desc, res);
+		if (rc)
+			break;
+	}
+	mutex_unlock(&hmem_resource_lock);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(walk_hmem_resources);
+
+static void __hmem_register_resource(int target_nid, struct resource *res)
 {
-	/* define a clean / non-busy resource for the platform device */
-	struct resource res = {
-		.start = r->start,
-		.end = r->end,
-		.flags = IORESOURCE_MEM,
-		.desc = IORES_DESC_SOFT_RESERVED,
-	};
 	struct platform_device *pdev;
-	struct memregion_info info;
-	int rc, id;
+	struct resource *new;
+	int rc;
 
-	if (nohmem)
+	new = __request_region(&hmem_active, res->start, resource_size(res), "",
+			       0);
+	if (!new) {
+		pr_debug("hmem range %pr already active\n", res);
 		return;
+	}
 
-	rc = region_intersects(res.start, resource_size(&res), IORESOURCE_MEM,
-			IORES_DESC_SOFT_RESERVED);
-	if (rc != REGION_INTERSECTS)
-		return;
+	new->desc = target_nid;
 
-	id = memregion_alloc(GFP_KERNEL);
-	if (id < 0) {
-		pr_err("memregion allocation failure for %pr\n", &res);
+	if (platform_initialized)
 		return;
-	}
 
-	pdev = platform_device_alloc("hmem", id);
+	pdev = platform_device_alloc("hmem_platform", 0);
 	if (!pdev) {
-		pr_err("hmem device allocation failure for %pr\n", &res);
-		goto out_pdev;
-	}
-
-	if (!__request_region(&hmem_active, res.start, resource_size(&res),
-			      dev_name(&pdev->dev), 0)) {
-		dev_dbg(&pdev->dev, "hmem range %pr already active\n", &res);
-		goto out_active;
-	}
-
-	pdev->dev.numa_node = numa_map_to_online_node(target_nid);
-	info = (struct memregion_info) {
-		.target_node = target_nid,
-	};
-	rc = platform_device_add_data(pdev, &info, sizeof(info));
-	if (rc < 0) {
-		pr_err("hmem memregion_info allocation failure for %pr\n", &res);
-		goto out_resource;
-	}
-
-	rc = platform_device_add_resources(pdev, &res, 1);
-	if (rc < 0) {
-		pr_err("hmem resource allocation failure for %pr\n", &res);
-		goto out_resource;
+		pr_err_once("failed to register device-dax hmem_platform device\n");
+		return;
 	}
 
 	rc = platform_device_add(pdev);
-	if (rc < 0) {
-		dev_err(&pdev->dev, "device add failed for %pr\n", &res);
-		goto out_resource;
-	}
+	if (rc)
+		platform_device_put(pdev);
+	else
+		platform_initialized = true;
+}
 
-	return;
+void hmem_register_resource(int target_nid, struct resource *res)
+{
+	if (nohmem)
+		return;
 
-out_resource:
-	__release_region(&hmem_active, res.start, resource_size(&res));
-out_active:
-	platform_device_put(pdev);
-out_pdev:
-	memregion_free(id);
+	mutex_lock(&hmem_resource_lock);
+	__hmem_register_resource(target_nid, res);
+	mutex_unlock(&hmem_resource_lock);
 }
 
 static __init int hmem_register_one(struct resource *res, void *data)
 {
-	hmem_register_device(phys_to_target_node(res->start), res);
+	hmem_register_resource(phys_to_target_node(res->start), res);
 
 	return 0;
 }
@@ -104,4 +92,4 @@ static __init int hmem_init(void)
  * As this is a fallback for address ranges unclaimed by the ACPI HMAT
  * parsing it must be at an initcall level greater than hmat_init().
  */
-late_initcall(hmem_init);
+device_initcall(hmem_init);
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 1bf040dbc834..e5fe8b39fb94 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -3,6 +3,7 @@
 #include <linux/memregion.h>
 #include <linux/module.h>
 #include <linux/pfn_t.h>
+#include <linux/dax.h>
 #include "../bus.h"
 
 static bool region_idle;
@@ -10,30 +11,32 @@ module_param_named(region_idle, region_idle, bool, 0644);
 
 static int dax_hmem_probe(struct platform_device *pdev)
 {
+	unsigned long flags = IORESOURCE_DAX_KMEM;
 	struct device *dev = &pdev->dev;
 	struct dax_region *dax_region;
 	struct memregion_info *mri;
 	struct dev_dax_data data;
 	struct dev_dax *dev_dax;
-	struct resource *res;
-	struct range range;
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
-		return -ENOMEM;
+	/*
+	 * @region_idle == true indicates that an administrative agent
+	 * wants to manipulate the range partitioning before the devices
+	 * are created, so do not send them to the dax_kmem driver by
+	 * default.
+	 */
+	if (region_idle)
+		flags = 0;
 
 	mri = dev->platform_data;
-	range.start = res->start;
-	range.end = res->end;
-	dax_region = alloc_dax_region(dev, pdev->id, &range, mri->target_node,
-			PMD_SIZE, 0);
+	dax_region = alloc_dax_region(dev, pdev->id, &mri->range,
+				      mri->target_node, PMD_SIZE, flags);
 	if (!dax_region)
 		return -ENOMEM;
 
 	data = (struct dev_dax_data) {
 		.dax_region = dax_region,
 		.id = -1,
-		.size = region_idle ? 0 : resource_size(res),
+		.size = region_idle ? 0 : range_len(&mri->range),
 	};
 	dev_dax = devm_create_dev_dax(&data);
 	if (IS_ERR(dev_dax))
@@ -44,22 +47,131 @@ static int dax_hmem_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int dax_hmem_remove(struct platform_device *pdev)
-{
-	/* devm handles teardown */
-	return 0;
-}
-
 static struct platform_driver dax_hmem_driver = {
 	.probe = dax_hmem_probe,
-	.remove = dax_hmem_remove,
 	.driver = {
 		.name = "hmem",
 	},
 };
 
-module_platform_driver(dax_hmem_driver);
+static void release_memregion(void *data)
+{
+	memregion_free((long) data);
+}
+
+static void release_hmem(void *pdev)
+{
+	platform_device_unregister(pdev);
+}
+
+static int hmem_register_device(struct device *host, int target_nid,
+				const struct resource *res)
+{
+	struct platform_device *pdev;
+	struct memregion_info info;
+	long id;
+	int rc;
+
+	if (IS_ENABLED(CONFIG_CXL_REGION) &&
+	    region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
+			      IORES_DESC_CXL) != REGION_DISJOINT) {
+		dev_dbg(host, "deferring range to CXL: %pr\n", res);
+		return 0;
+	}
+
+	rc = region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
+			       IORES_DESC_SOFT_RESERVED);
+	if (rc != REGION_INTERSECTS)
+		return 0;
+
+	id = memregion_alloc(GFP_KERNEL);
+	if (id < 0) {
+		dev_err(host, "memregion allocation failure for %pr\n", res);
+		return -ENOMEM;
+	}
+	rc = devm_add_action_or_reset(host, release_memregion, (void *) id);
+	if (rc)
+		return rc;
+
+	pdev = platform_device_alloc("hmem", id);
+	if (!pdev) {
+		dev_err(host, "device allocation failure for %pr\n", res);
+		return -ENOMEM;
+	}
+
+	pdev->dev.numa_node = numa_map_to_online_node(target_nid);
+	info = (struct memregion_info) {
+		.target_node = target_nid,
+		.range = {
+			.start = res->start,
+			.end = res->end,
+		},
+	};
+	rc = platform_device_add_data(pdev, &info, sizeof(info));
+	if (rc < 0) {
+		dev_err(host, "memregion_info allocation failure for %pr\n",
+		       res);
+		goto out_put;
+	}
+
+	rc = platform_device_add(pdev);
+	if (rc < 0) {
+		dev_err(host, "%s add failed for %pr\n", dev_name(&pdev->dev),
+			res);
+		goto out_put;
+	}
+
+	return devm_add_action_or_reset(host, release_hmem, pdev);
+
+out_put:
+	platform_device_put(pdev);
+	return rc;
+}
+
+static int dax_hmem_platform_probe(struct platform_device *pdev)
+{
+	return walk_hmem_resources(&pdev->dev, hmem_register_device);
+}
+
+static struct platform_driver dax_hmem_platform_driver = {
+	.probe = dax_hmem_platform_probe,
+	.driver = {
+		.name = "hmem_platform",
+	},
+};
+
+static __init int dax_hmem_init(void)
+{
+	int rc;
+
+	rc = platform_driver_register(&dax_hmem_platform_driver);
+	if (rc)
+		return rc;
+
+	rc = platform_driver_register(&dax_hmem_driver);
+	if (rc)
+		platform_driver_unregister(&dax_hmem_platform_driver);
+
+	return rc;
+}
+
+static __exit void dax_hmem_exit(void)
+{
+	platform_driver_unregister(&dax_hmem_driver);
+	platform_driver_unregister(&dax_hmem_platform_driver);
+}
+
+module_init(dax_hmem_init);
+module_exit(dax_hmem_exit);
+
+/* Allow for CXL to define its own dax regions */
+#if IS_ENABLED(CONFIG_CXL_REGION)
+#if IS_MODULE(CONFIG_CXL_ACPI)
+MODULE_SOFTDEP("pre: cxl_acpi");
+#endif
+#endif
 
 MODULE_ALIAS("platform:hmem*");
+MODULE_ALIAS("platform:hmem_platform*");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Intel Corporation");
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 4852a2dbdb27..7b36db6f1cbd 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -146,7 +146,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		if (rc) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
 					i, range.start, range.end);
-			release_resource(res);
+			remove_resource(res);
 			kfree(res);
 			data->res[i] = NULL;
 			if (mapped)
@@ -195,7 +195,7 @@ static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
 
 		rc = remove_memory(range.start, range_len(&range));
 		if (rc == 0) {
-			release_resource(data->res[i]);
+			remove_resource(data->res[i]);
 			kfree(data->res[i]);
 			data->res[i] = NULL;
 			success++;
@@ -239,6 +239,7 @@ static void dev_dax_kmem_remove(struct dev_dax *dev_dax)
 static struct dax_device_driver device_dax_kmem_driver = {
 	.probe = dev_dax_kmem_probe,
 	.remove = dev_dax_kmem_remove,
+	.type = DAXDRV_KMEM_TYPE,
 };
 
 static int __init dax_kmem_init(void)