[PATCH v10 4/8] mm/demotion/dax/kmem: Set node's performance level to MEMTIER_PERF_LEVEL_PMEM

[Aneesh Kumar K.V]

By default, all nodes are assigned to the default memory tier which
is the memory tier designated for nodes with DRAM

Set dax kmem device node's tier to slower memory tier by assigning
performance level to MEMTIER_PERF_LEVEL_PMEM. PMEM tier
appears below the default memory tier in demotion order.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
---
 arch/powerpc/platforms/pseries/papr_scm.c | 41 ++++++++++++++++++++---
 drivers/acpi/nfit/core.c                  | 41 ++++++++++++++++++++++-
 2 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 82cae08976bc..3b6164418d6f 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -14,6 +14,8 @@
 #include <linux/delay.h>
 #include <linux/seq_buf.h>
 #include <linux/nd.h>
+#include <linux/memory.h>
+#include <linux/memory-tiers.h>
 
 #include <asm/plpar_wrappers.h>
 #include <asm/papr_pdsm.h>
@@ -98,6 +100,7 @@ struct papr_scm_priv {
 	bool hcall_flush_required;
 
 	uint64_t bound_addr;
+	int target_node;
 
 	struct nvdimm_bus_descriptor bus_desc;
 	struct nvdimm_bus *bus;
@@ -1278,6 +1281,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	p->bus_desc.module = THIS_MODULE;
 	p->bus_desc.of_node = p->pdev->dev.of_node;
 	p->bus_desc.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);
+	p->target_node = dev_to_node(&p->pdev->dev);
 
 	/* Set the dimm command family mask to accept PDSMs */
 	set_bit(NVDIMM_FAMILY_PAPR, &p->bus_desc.dimm_family_mask);
@@ -1322,7 +1326,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	mapping.size = p->blocks * p->block_size; // XXX: potential overflow?
 
 	memset(&ndr_desc, 0, sizeof(ndr_desc));
-	target_nid = dev_to_node(&p->pdev->dev);
+	target_nid = p->target_node;
 	online_nid = numa_map_to_online_node(target_nid);
 	ndr_desc.numa_node = online_nid;
 	ndr_desc.target_node = target_nid;
@@ -1582,15 +1586,42 @@ static struct platform_driver papr_scm_driver = {
 	},
 };
 
+static int papr_scm_callback(struct notifier_block *self,
+			     unsigned long action, void *arg)
+{
+	struct memory_notify *mnb = arg;
+	int nid = mnb->status_change_nid;
+	struct papr_scm_priv *p;
+
+	if (nid == NUMA_NO_NODE || action != MEM_ONLINE)
+		return NOTIFY_OK;
+
+	mutex_lock(&papr_ndr_lock);
+	list_for_each_entry(p, &papr_nd_regions, region_list) {
+		if (p->target_node == nid) {
+			node_devices[nid]->perf_level = MEMTIER_PERF_LEVEL_PMEM;
+			break;
+		}
+	}
+
+	mutex_unlock(&papr_ndr_lock);
+	return NOTIFY_OK;
+}
+
 static int __init papr_scm_init(void)
 {
 	int ret;
 
 	ret = platform_driver_register(&papr_scm_driver);
-	if (!ret)
-		mce_register_notifier(&mce_ue_nb);
-
-	return ret;
+	if (ret)
+		return ret;
+	mce_register_notifier(&mce_ue_nb);
+	/*
+	 * register a memory hotplug notifier at prio 2 so that we
+	 * can update the perf level for the node.
+	 */
+	hotplug_memory_notifier(papr_scm_callback, MEMTIER_HOTPLUG_PRIO + 1);
+	return 0;
 }
 module_init(papr_scm_init);
 
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index ae5f4acf2675..7ea1017ef790 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -15,6 +15,8 @@
 #include <linux/sort.h>
 #include <linux/io.h>
 #include <linux/nd.h>
+#include <linux/memory.h>
+#include <linux/memory-tiers.h>
 #include <asm/cacheflush.h>
 #include <acpi/nfit.h>
 #include "intel.h"
@@ -3470,6 +3472,39 @@ static struct acpi_driver acpi_nfit_driver = {
 	},
 };
 
+static int nfit_callback(struct notifier_block *self,
+			 unsigned long action, void *arg)
+{
+	bool found = false;
+	struct memory_notify *mnb = arg;
+	int nid = mnb->status_change_nid;
+	struct nfit_spa *nfit_spa;
+	struct acpi_nfit_desc *acpi_desc;
+
+	if (nid == NUMA_NO_NODE || action != MEM_ONLINE)
+		return NOTIFY_OK;
+
+	mutex_lock(&acpi_desc_lock);
+	list_for_each_entry(acpi_desc, &acpi_descs, list) {
+		mutex_lock(&acpi_desc->init_mutex);
+		list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
+			struct acpi_nfit_system_address *spa = nfit_spa->spa;
+			int target_node = pxm_to_node(spa->proximity_domain);
+
+			if (target_node == nid) {
+				node_devices[nid]->perf_level = MEMTIER_PERF_LEVEL_PMEM;
+				found = true;
+				break;
+			}
+		}
+		mutex_unlock(&acpi_desc->init_mutex);
+		if (found)
+			break;
+	}
+	mutex_unlock(&acpi_desc_lock);
+	return NOTIFY_OK;
+}
+
 static __init int nfit_init(void)
 {
 	int ret;
@@ -3509,7 +3544,11 @@ static __init int nfit_init(void)
 		nfit_mce_unregister();
 		destroy_workqueue(nfit_wq);
 	}
-
+	/*
+	 * register a memory hotplug notifier at prio 2 so that we
+	 * can update the perf level for the node.
+	 */
+	hotplug_memory_notifier(nfit_callback, MEMTIER_HOTPLUG_PRIO + 1);
 	return ret;
 
 }
-- 
2.36.1