This bit is used by dax/kmem to determine whether to set the
MHP_SPM_NODE flags, which determines whether the hotplug memory
is SysRAM or Specific Purpose Memory.

Signed-off-by: Gregory Price <[email protected]>
---
 drivers/dax/bus.c         | 39 +++++++++++++++++++++++++++++++++++++++
 drivers/dax/bus.h         |  1 +
 drivers/dax/dax-private.h |  1 +
 drivers/dax/kmem.c        |  2 ++
 4 files changed, 43 insertions(+)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index fde29e0ad68b..b0de43854112 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1361,6 +1361,43 @@ static ssize_t memmap_on_memory_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(memmap_on_memory);
 
+static ssize_t spm_node_show(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+       struct dev_dax *dev_dax = to_dev_dax(dev);
+
+       return sysfs_emit(buf, "%d\n", dev_dax->spm_node);
+}
+
+static ssize_t spm_node_store(struct device *dev,
+                             struct device_attribute *attr,
+                             const char *buf, size_t len)
+{
+       struct dev_dax *dev_dax = to_dev_dax(dev);
+       bool val;
+       int rc;
+
+       rc = kstrtobool(buf, &val);
+       if (rc)
+               return rc;
+
+       rc = down_write_killable(&dax_dev_rwsem);
+       if (rc)
+               return rc;
+
+       if (dev_dax->spm_node != val && dev->driver &&
+           to_dax_drv(dev->driver)->type == DAXDRV_KMEM_TYPE) {
+               up_write(&dax_dev_rwsem);
+               return -EBUSY;
+       }
+
+       dev_dax->spm_node = val;
+       up_write(&dax_dev_rwsem);
+
+       return len;
+}
+static DEVICE_ATTR_RW(spm_node);
+
 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int 
n)
 {
        struct device *dev = container_of(kobj, struct device, kobj);
@@ -1388,6 +1425,7 @@ static struct attribute *dev_dax_attributes[] = {
        &dev_attr_resource.attr,
        &dev_attr_numa_node.attr,
        &dev_attr_memmap_on_memory.attr,
+       &dev_attr_spm_node.attr,
        NULL,
 };
 
@@ -1494,6 +1532,7 @@ 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->spm_node = data->spm_node;
 
        inode = dax_inode(dax_dev);
        dev->devt = inode->i_rdev;
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index cbbf64443098..51ed961b6a3c 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -24,6 +24,7 @@ struct dev_dax_data {
        resource_size_t size;
        int id;
        bool memmap_on_memory;
+       bool spm_node;
 };
 
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index 0867115aeef2..3d1b1f996383 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -89,6 +89,7 @@ struct dev_dax {
        struct device dev;
        struct dev_pagemap *pgmap;
        bool memmap_on_memory;
+       bool spm_node;
        int nr_range;
        struct dev_dax_range *ranges;
 };
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index c036e4d0b610..3c3dd1cd052c 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -169,6 +169,8 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
                mhp_flags = MHP_NID_IS_MGID;
                if (dev_dax->memmap_on_memory)
                        mhp_flags |= MHP_MEMMAP_ON_MEMORY;
+               if (dev_dax->spm_node)
+                       mhp_flags |= MHP_SPM_NODE;
 
                /*
                 * Ensure that future kexec'd kernels will not treat
-- 
2.51.1


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