Merge branch 'for-7.2/cxl-type2-attach-region' into cxl-for-next

cxl: Add dummy function for cxl_memdev_attach_region for !CONFIG_CXL_REGION
cxl/region: Introduce devm_cxl_probe_mem()
cxl/memdev: Introduce cxl_class_memdev_type
cxl/memdev: Pin parents for entire memdev lifetime
cxl/region: Resolve region deletion races
cxl/region: Block region delete during region creation

10 files changed, 304 insertions, 63 deletions

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 82ca3a476708..07555ae63859 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -52,6 +52,7 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
 		   u64 dpa);
 int devm_cxl_add_dax_region(struct cxl_region *cxlr);
 int devm_cxl_add_pmem_region(struct cxl_region *cxlr);
+void kill_regions(struct cxl_root_decoder *cxlrd);
 
 #else
 static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr,
@@ -81,6 +82,7 @@ static inline int cxl_region_init(void)
 static inline void cxl_region_exit(void)
 {
 }
+static inline void kill_regions(struct cxl_root_decoder *cxlrd) { };
 #define CXL_REGION_ATTR(x) NULL
 #define CXL_REGION_TYPE(x) NULL
 #define SET_CXL_REGION_ATTR(x)
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 80e65690eb77..33a3d2e7b13a 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -25,9 +25,11 @@ static DEFINE_IDA(cxl_memdev_ida);
 static void cxl_memdev_release(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+	struct device *parent = dev->parent;
 
 	ida_free(&cxl_memdev_ida, cxlmd->id);
 	kfree(cxlmd);
+	put_device(parent);
 }
 
 static char *cxl_memdev_devnode(const struct device *dev, umode_t *mode, kuid_t *uid,
@@ -572,16 +574,23 @@ void cxl_memdev_update_perf(struct cxl_memdev *cxlmd)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_memdev_update_perf, "CXL");
 
-static const struct device_type cxl_memdev_type = {
+static const struct device_type cxl_class_memdev_type = {
 	.name = "cxl_memdev",
 	.release = cxl_memdev_release,
 	.devnode = cxl_memdev_devnode,
 	.groups = cxl_memdev_attribute_groups,
 };
 
+static const struct device_type cxl_memdev_type = {
+	.name = "cxl_memdev",
+	.release = cxl_memdev_release,
+	.devnode = cxl_memdev_devnode,
+};
+
 bool is_cxl_memdev(const struct device *dev)
 {
-	return dev->type == &cxl_memdev_type;
+	return (dev->type == &cxl_class_memdev_type ||
+		dev->type == &cxl_memdev_type);
 }
 EXPORT_SYMBOL_NS_GPL(is_cxl_memdev, "CXL");
 
@@ -707,10 +716,13 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 	dev = &cxlmd->dev;
 	device_initialize(dev);
 	lockdep_set_class(&dev->mutex, &cxl_memdev_key);
-	dev->parent = cxlds->dev;
+	dev->parent = get_device(cxlds->dev);
 	dev->bus = &cxl_bus_type;
 	dev->devt = MKDEV(cxl_mem_major, cxlmd->id);
-	dev->type = &cxl_memdev_type;
+	if (cxlds->type == CXL_DEVTYPE_DEVMEM)
+		dev->type = &cxl_memdev_type;
+	else
+		dev->type = &cxl_class_memdev_type;
 	device_set_pm_not_required(dev);
 	INIT_WORK(&cxlmd->detach_work, detach_memdev);
 
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index c5aacd7054f1..1215ee4f4035 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -458,6 +458,8 @@ static void cxl_root_decoder_release(struct device *dev)
 
 	if (atomic_read(&cxlrd->region_id) >= 0)
 		memregion_free(atomic_read(&cxlrd->region_id));
+	mutex_destroy(&cxlrd->regions_lock);
+	xa_destroy(&cxlrd->regions);
 	__cxl_decoder_release(&cxlrd->cxlsd.cxld);
 	kfree(cxlrd);
 }
@@ -2016,7 +2018,8 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 		return ERR_PTR(rc);
 	}
 
-	mutex_init(&cxlrd->range_lock);
+	mutex_init(&cxlrd->regions_lock);
+	xa_init(&cxlrd->regions);
 
 	cxld = &cxlsd->cxld;
 	cxld->dev.type = &cxl_decoder_root_type;
@@ -2192,6 +2195,8 @@ static void cxld_unregister(void *dev)
 	if (is_endpoint_decoder(dev))
 		cxl_decoder_detach(NULL, to_cxl_endpoint_decoder(dev), -1,
 				   DETACH_INVALIDATE);
+	if (is_root_decoder(dev))
+		kill_regions(to_cxl_root_decoder(dev));
 
 	device_unregister(dev);
 }
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 66c328d1c14e..1e211542b6b6 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1148,6 +1148,19 @@ static int cxl_rr_assign_decoder(struct cxl_port *port, struct cxl_region *cxlr,
 static void cxl_region_setup_flags(struct cxl_region *cxlr,
 				   struct cxl_decoder *cxld)
 {
+	if (is_endpoint_decoder(&cxld->dev)) {
+		struct cxl_endpoint_decoder *cxled = to_cxl_endpoint_decoder(&cxld->dev);
+		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+
+		/*
+		 * When a region's memdevs specify an @attach method the attach
+		 * provider is responsible for dispositioning the region for
+		 * both probe and userspace management
+		 */
+		if (cxlmd->attach)
+			set_bit(CXL_REGION_F_LOCK, &cxlr->flags);
+	}
+
 	if (cxld->flags & CXL_DECODER_F_LOCK) {
 		set_bit(CXL_REGION_F_LOCK, &cxlr->flags);
 		clear_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags);
@@ -2546,12 +2559,13 @@ static struct cxl_region *to_cxl_region(struct device *dev)
 	return container_of(dev, struct cxl_region, dev);
 }
 
-static void unregister_region(void *_cxlr)
+static void unregister_region(struct cxl_region *cxlr)
 {
-	struct cxl_region *cxlr = _cxlr;
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
 	struct cxl_region_params *p = &cxlr->params;
 	int i;
 
+	xa_erase(&cxlrd->regions, cxlr->id);
 	device_del(&cxlr->dev);
 
 	/*
@@ -2568,6 +2582,17 @@ static void unregister_region(void *_cxlr)
 	put_device(&cxlr->dev);
 }
 
+static void endpoint_unregister_region(void *_cxlr)
+{
+	struct cxl_region *cxlr = _cxlr;
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
+
+	guard(mutex)(&cxlrd->regions_lock);
+	if (xa_load(&cxlrd->regions, cxlr->id))
+		unregister_region(cxlr);
+	put_device(&cxlr->dev);
+}
+
 static struct lock_class_key cxl_region_key;
 
 static struct cxl_region *cxl_region_alloc(struct cxl_root_decoder *cxlrd, int id)
@@ -2682,6 +2707,19 @@ static int cxl_region_calculate_adistance(struct notifier_block *nb,
 	return NOTIFY_STOP;
 }
 
+/* unwind all remaining regions */
+void kill_regions(struct cxl_root_decoder *cxlrd)
+{
+	unsigned long index;
+	struct cxl_region *cxlr;
+
+	guard(mutex)(&cxlrd->regions_lock);
+	/* no more region creation */
+	cxlrd->dead = true;
+	xa_for_each(&cxlrd->regions, index, cxlr)
+		unregister_region(cxlr);
+}
+
 /**
  * devm_cxl_add_region - Adds a region to a decoder
  * @cxlrd: root decoder
@@ -2720,14 +2758,15 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
 	if (rc)
 		goto err;
 
-	rc = devm_add_action_or_reset(port->uport_dev, unregister_region, cxlr);
-	if (rc)
+	rc = xa_insert(&cxlrd->regions, cxlr->id, cxlr, GFP_KERNEL);
+	if (rc) {
+		unregister_region(cxlr);
 		return ERR_PTR(rc);
+	}
 
 	dev_dbg(port->uport_dev, "%s: created %s\n",
 		dev_name(&cxlrd->cxlsd.cxld.dev), dev_name(dev));
 	return cxlr;
-
 err:
 	put_device(dev);
 	return ERR_PTR(rc);
@@ -2756,6 +2795,9 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 {
 	int rc;
 
+	if (cxlrd->dead)
+		return ERR_PTR(-ENXIO);
+
 	switch (mode) {
 	case CXL_PARTMODE_RAM:
 	case CXL_PARTMODE_PMEM:
@@ -2788,6 +2830,10 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
 	if (rc != 1)
 		return -EINVAL;
 
+	ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock);
+	if ((rc = ACQUIRE_ERR(mutex_intr, &regions_lock)))
+		return rc;
+
 	cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM);
 	if (IS_ERR(cxlr))
 		return PTR_ERR(cxlr);
@@ -2827,33 +2873,27 @@ static ssize_t region_show(struct device *dev, struct device_attribute *attr,
 }
 DEVICE_ATTR_RO(region);
 
-static struct cxl_region *
-cxl_find_region_by_name(struct cxl_root_decoder *cxlrd, const char *name)
-{
-	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
-	struct device *region_dev;
-
-	region_dev = device_find_child_by_name(&cxld->dev, name);
-	if (!region_dev)
-		return ERR_PTR(-ENODEV);
-
-	return to_cxl_region(region_dev);
-}
-
 static ssize_t delete_region_store(struct device *dev,
 				   struct device_attribute *attr,
 				   const char *buf, size_t len)
 {
 	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
-	struct cxl_port *port = to_cxl_port(dev->parent);
 	struct cxl_region *cxlr;
+	int rc, id;
 
-	cxlr = cxl_find_region_by_name(cxlrd, buf);
-	if (IS_ERR(cxlr))
-		return PTR_ERR(cxlr);
+	ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock);
+	if ((rc = ACQUIRE_ERR(mutex_intr, &regions_lock)))
+		return rc;
 
-	devm_release_action(port->uport_dev, unregister_region, cxlr);
-	put_device(&cxlr->dev);
+	rc = sscanf(buf, "region%d\n", &id);
+	if (rc != 1)
+		return -EINVAL;
+
+	cxlr = xa_load(&cxlrd->regions, id);
+	if (!cxlr || !sysfs_streq(buf, dev_name(&cxlr->dev)))
+		return -ENODEV;
+
+	unregister_region(cxlr);
 
 	return len;
 }
@@ -3718,7 +3758,6 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 {
 	struct cxl_endpoint_decoder *cxled = ctx->cxled;
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-	struct cxl_port *port = cxlrd_to_port(cxlrd);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	int rc, part = READ_ONCE(cxled->part);
 	struct cxl_region *cxlr;
@@ -3742,7 +3781,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 
 	rc = __construct_region(cxlr, ctx);
 	if (rc) {
-		devm_release_action(port->uport_dev, unregister_region, cxlr);
+		unregister_region(cxlr);
 		return ERR_PTR(rc);
 	}
 
@@ -3788,12 +3827,11 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 	 * for the HPA range, one does the construction and the others
 	 * add to that.
 	 */
-	mutex_lock(&cxlrd->range_lock);
+	guard(mutex)(&cxlrd->regions_lock);
 	struct cxl_region *cxlr __free(put_cxl_region) =
 		cxl_find_region_by_range(cxlrd, &ctx.hpa_range);
 	if (!cxlr)
 		cxlr = construct_region(cxlrd, &ctx);
-	mutex_unlock(&cxlrd->range_lock);
 
 	rc = PTR_ERR_OR_ZERO(cxlr);
 	if (rc)
@@ -4055,6 +4093,103 @@ static int cxl_region_can_probe(struct cxl_region *cxlr)
 	return 0;
 }
 
+static int first_mapped_decoder(struct device *dev, const void *data)
+{
+	struct cxl_endpoint_decoder *cxled;
+
+	if (!is_endpoint_decoder(dev))
+		return 0;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	if (cxled->cxld.region)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Runs in cxl_mem_probe context after successful endpoint probe, assumes the
+ * simple case of single mapped decoder per memdev.
+ */
+int cxl_memdev_attach_region(struct cxl_memdev *cxlmd)
+{
+	struct cxl_attach_region *attach =
+		container_of(cxlmd->attach, typeof(*attach), attach);
+	struct cxl_port *endpoint = cxlmd->endpoint;
+	struct cxl_endpoint_decoder *cxled;
+	struct cxl_region *cxlr;
+	int rc;
+
+	/* hold endpoint lock to setup autoremove of the region */
+	guard(device)(&endpoint->dev);
+	if (!endpoint->dev.driver)
+		return -ENXIO;
+	guard(rwsem_read)(&cxl_rwsem.region);
+	guard(rwsem_read)(&cxl_rwsem.dpa);
+
+	/*
+	 * TODO auto-instantiate a region, for now assume this will find an
+	 * auto-region
+	 */
+	struct device *dev __free(put_device) =
+		device_find_child(&endpoint->dev, NULL, first_mapped_decoder);
+
+	if (!dev) {
+		dev_dbg(cxlmd->cxlds->dev, "no region found for memdev %s\n",
+			dev_name(&cxlmd->dev));
+		return -ENXIO;
+	}
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	cxlr = cxled->cxld.region;
+
+	if (cxlr->params.state < CXL_CONFIG_COMMIT) {
+		dev_dbg(cxlmd->cxlds->dev,
+			"region %s not committed for memdev %s\n",
+			dev_name(&cxlr->dev), dev_name(&cxlmd->dev));
+		return -ENXIO;
+	}
+
+	if (cxlr->params.nr_targets > 1) {
+		dev_dbg(cxlmd->cxlds->dev,
+			"Only attach to local non-interleaved region\n");
+		return -ENXIO;
+	}
+
+	/* Only teardown regions that pass validation, ignore the rest */
+	get_device(&cxlr->dev);
+	rc = devm_add_action_or_reset(&endpoint->dev,
+				      endpoint_unregister_region, cxlr);
+	if (rc)
+		return rc;
+
+	attach->hpa_range = (struct range) {
+		.start = cxlr->params.res->start,
+		.end = cxlr->params.res->end,
+	};
+	return 0;
+}
+EXPORT_SYMBOL_FOR_MODULES(cxl_memdev_attach_region, "cxl_mem");
+
+/*
+ * The presence of an attach method indicates that the region is designated for
+ * a purpose outside of CXL core memory expansion defaults.
+ */
+static bool cxl_region_has_memdev_attach(struct cxl_region *cxlr)
+{
+	struct cxl_region_params *p = &cxlr->params;
+
+	for (int i = 0; i < p->nr_targets; i++) {
+		struct cxl_endpoint_decoder *cxled = p->targets[i];
+		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+
+		if (cxlmd->attach)
+			return true;
+	}
+
+	return false;
+}
+
 static int cxl_region_probe(struct device *dev)
 {
 	struct cxl_region *cxlr = to_cxl_region(dev);
@@ -4086,6 +4221,9 @@ static int cxl_region_probe(struct device *dev)
 	if (rc)
 		return rc;
 
+	if (cxl_region_has_memdev_attach(cxlr))
+		return 0;
+
 	switch (cxlr->mode) {
 	case CXL_PARTMODE_PMEM:
 		rc = devm_cxl_region_edac_register(cxlr);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 4a884821ff7c..c0e5308e4d1b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -371,7 +371,9 @@ struct cxl_rd_ops {
  * @cache_size: extended linear cache size if exists, otherwise zero.
  * @region_id: region id for next region provisioning event
  * @platform_data: platform specific configuration data
- * @range_lock: sync region autodiscovery by address range
+ * @regions_lock: sync region discovery, construction, and deletion
+ * @regions: regions to remove at root decoder destruct time
+ * @dead: root decoder dead to region creation
  * @qos_class: QoS performance class cookie
  * @ops: CXL root decoder operations
  * @cxlsd: base cxl switch decoder
@@ -381,7 +383,9 @@ struct cxl_root_decoder {
 	resource_size_t cache_size;
 	atomic_t region_id;
 	void *platform_data;
-	struct mutex range_lock;
+	struct mutex regions_lock;
+	struct xarray regions;
+	bool dead;
 	int qos_class;
 	struct cxl_rd_ops ops;
 	struct cxl_switch_decoder cxlsd;
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 776c50d1db51..ed419d0c59f2 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -34,10 +34,6 @@
 	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
 	 CXLMDEV_RESET_NEEDED_NOT)
 
-struct cxl_memdev_attach {
-	int (*probe)(struct cxl_memdev *cxlmd);
-};
-
 /**
  * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
  * @dev: driver core device object
@@ -101,10 +97,36 @@ static inline bool is_cxl_endpoint(struct cxl_port *port)
 	return is_cxl_memdev(port->uport_dev);
 }
 
+struct cxl_memdev_attach {
+	int (*probe)(struct cxl_memdev *cxlmd);
+};
+
+/**
+ * struct cxl_attach_region - coordinate mapping a region at memdev registration
+ * @attach: common core attachment descriptor
+ * @hpa_range: physical address range of the region
+ *
+ * For the common simple case of a CXL device with private (non-general purpose
+ * / "accelerator") memory, enumerate firmware instantiated region, or
+ * instantiate a region for the device's capacity. Destroy the region on detach.
+ */
+struct cxl_attach_region {
+	struct cxl_memdev_attach attach;
+	struct range hpa_range;
+};
+
+#ifdef CONFIG_CXL_REGION
+int cxl_memdev_attach_region(struct cxl_memdev *cxlmd);
+#else
+static inline int cxl_memdev_attach_region(struct cxl_memdev *cxlmd)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+struct cxl_memdev *devm_cxl_add_classdev(struct cxl_dev_state *cxlds);
 struct cxl_memdev *__devm_cxl_add_memdev(struct cxl_dev_state *cxlds,
 					 const struct cxl_memdev_attach *attach);
-struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds,
-				       const struct cxl_memdev_attach *attach);
 int devm_cxl_sanitize_setup_notifier(struct device *host,
 				     struct cxl_memdev *cxlmd);
 struct cxl_memdev_state;
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index ab88eaa31d1d..798e5c369cfc 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -75,6 +75,26 @@ static int cxl_debugfs_poison_clear(void *data, u64 dpa)
 DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
 			 cxl_debugfs_poison_clear, "%llx\n");
 
+static void cxl_memdev_poison_enable(struct cxl_memdev_state *mds,
+				     struct cxl_memdev *cxlmd,
+				     struct dentry *dentry)
+{
+	/*
+	 * Avoid poison debugfs for DEVMEM aka accelerators as they rely on
+	 * cxl_memdev_state.
+	 */
+	if (!mds)
+		return;
+
+	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
+		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_inject_fops);
+
+	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
+		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_clear_fops);
+}
+
 static int cxl_mem_probe(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
@@ -102,12 +122,7 @@ static int cxl_mem_probe(struct device *dev)
 	dentry = cxl_debugfs_create_dir(dev_name(dev));
 	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);
 
-	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
-		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
-				    &cxl_poison_inject_fops);
-	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
-		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
-				    &cxl_poison_clear_fops);
+	cxl_memdev_poison_enable(mds, cxlmd, dentry);
 
 	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
 	if (rc)
@@ -178,27 +193,59 @@ static int cxl_mem_probe(struct device *dev)
 }
 
 /**
- * devm_cxl_add_memdev - Add a CXL memory device
+ * devm_cxl_add_classdev - Add a CXL memory class-code device
  * @cxlds: CXL device state to associate with the memdev
- * @attach: Caller depends on CXL topology attachment
  *
  * Upon return the device will have had a chance to attach to the
  * cxl_mem driver, but may fail to attach if the CXL topology is not ready
  * (hardware CXL link down, or software platform CXL root not attached).
  *
- * When @attach is NULL it indicates the caller wants the memdev to remain
- * registered even if it does not immediately attach to the CXL hierarchy. When
- * @attach is provided a cxl_mem_probe() failure leads to failure of this routine.
+ * The parent of the resulting device and the devm context for allocations is
+ * @cxlds->dev.
+ */
+struct cxl_memdev *devm_cxl_add_classdev(struct cxl_dev_state *cxlds)
+{
+	return __devm_cxl_add_memdev(cxlds, NULL);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_add_classdev, "CXL");
+
+/**
+ * devm_cxl_probe_mem - Add a CXL memory device and probe its region
+ * @cxlds: CXL device state to associate with the memdev
+ * @hpa_range: CXL.mem physical address range result
+ *
+ * Upon return the device will have had a chance to attach to the
+ * cxl_mem driver, but may fail to attach if the CXL topology is not ready
+ * (hardware CXL link down, or software platform CXL root not attached).
+ *
+ * Failure to probe the memdev and/or setup a region for the memdev
+ * results in this function failing.
  *
  * The parent of the resulting device and the devm context for allocations is
  * @cxlds->dev.
  */
-struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds,
-				       const struct cxl_memdev_attach *attach)
+struct cxl_memdev *devm_cxl_probe_mem(struct cxl_dev_state *cxlds,
+				      struct range *hpa_range)
 {
-	return __devm_cxl_add_memdev(cxlds, attach);
+	struct cxl_attach_region *attach =
+		devm_kmalloc(cxlds->dev, sizeof(*attach), GFP_KERNEL);
+	struct cxl_memdev *cxlmd;
+
+	if (!attach)
+		return ERR_PTR(-ENOMEM);
+
+	*attach = (struct cxl_attach_region) {
+		.attach = {
+			   .probe = cxl_memdev_attach_region,
+		},
+		.hpa_range = { 0, -1 },
+	};
+
+	cxlmd = __devm_cxl_add_memdev(cxlds, &attach->attach);
+	*hpa_range = attach->hpa_range;
+	return cxlmd;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_add_memdev, "CXL");
+EXPORT_SYMBOL_NS_GPL(devm_cxl_probe_mem, "CXL");
 
 static ssize_t trigger_poison_list_store(struct device *dev,
 					 struct device_attribute *attr,
@@ -216,16 +263,24 @@ static ssize_t trigger_poison_list_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(trigger_poison_list);
 
-static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
+static bool cxl_poison_attr_visible(struct kobject *kobj, struct attribute *a)
 {
 	struct device *dev = kobj_to_dev(kobj);
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 
-	if (a == &dev_attr_trigger_poison_list.attr)
-		if (!test_bit(CXL_POISON_ENABLED_LIST,
-			      mds->poison.enabled_cmds))
-			return 0;
+	if (!mds ||
+	    !test_bit(CXL_POISON_ENABLED_LIST, mds->poison.enabled_cmds))
+		return false;
+
+	return true;
+}
+
+static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	if (a == &dev_attr_trigger_poison_list.attr &&
+	    !cxl_poison_attr_visible(kobj, a))
+		return 0;
 
 	return a->mode;
 }
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index bace662dc988..267c679b0b3c 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -878,7 +878,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		dev_dbg(&pdev->dev, "No CXL Features discovered\n");
 
-	cxlmd = devm_cxl_add_memdev(cxlds, NULL);
+	cxlmd = devm_cxl_add_classdev(cxlds);
 	if (IS_ERR(cxlmd))
 		return PTR_ERR(cxlmd);
 
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index fa7269154620..016c74fb747c 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -223,4 +223,7 @@ struct cxl_dev_state *_devm_cxl_dev_state_create(struct device *dev,
 		(drv_struct *)_devm_cxl_dev_state_create(parent, type, serial, dvsec,	\
 						      sizeof(drv_struct), mbox);	\
 	})
+
+struct cxl_memdev *devm_cxl_probe_mem(struct cxl_dev_state *cxlds,
+				      struct range *range);
 #endif /* __CXL_CXL_H__ */
diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 739343cd5802..a1d170f88fee 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -1790,7 +1790,7 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 
 	cxl_mock_add_event_logs(&mdata->mes);
 
-	cxlmd = devm_cxl_add_memdev(cxlds, NULL);
+	cxlmd = devm_cxl_add_classdev(cxlds);
 	if (IS_ERR(cxlmd))
 		return PTR_ERR(cxlmd);