[RFC PATCH 6/8] nvdimm: add PPC64 'device-node' property

[Daniel Henrique Barboza <danielhb413@gmail.com>]

The spapr-nvdimm driver is able to operate in two ways. The first
one is as a regular memory in which the NUMA node of the parent
pc-dimm class is used. The second mode, as persistent memory, allows for
a different NUMA node to be used based on the locality of the device.

At this moment we don't have a way to express this second NUMA node for
the persistent memory mode. This patch introduces a new 'device-node'
property that will be used by the PPC64 spapr-nvdimm driver to set a
second NUMA node for the nvdimm.

CC: Shivaprasad G Bhat <sbhat@linux.ibm.com>
CC: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/mem/nvdimm.c         | 28 ++++++++++++++++++++++++++++
 include/hw/mem/nvdimm.h | 12 ++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
index 7397b67156..030ccf7575 100644
--- a/hw/mem/nvdimm.c
+++ b/hw/mem/nvdimm.c
@@ -96,6 +96,29 @@ static void nvdimm_set_uuid(Object *obj, Visitor *v, const char *name,
     g_free(value);
 }
 
+static void nvdimm_get_device_node(Object *obj, Visitor *v,
+                                         const char *name, void *opaque,
+                                         Error **errp)
+{
+    NVDIMMDevice *nvdimm = NVDIMM(obj);
+    uint8_t value = nvdimm->device_node;
+
+    visit_type_uint8(v, name, &value, errp);
+}
+
+static void nvdimm_set_device_node(Object *obj, Visitor *v,
+                                         const char *name, void *opaque,
+                                         Error **errp)
+{
+    NVDIMMDevice *nvdimm = NVDIMM(obj);
+    uint8_t value;
+
+    if (!visit_type_uint8(v, name, &value, errp)) {
+        return;
+    }
+
+    nvdimm->device_node = value;
+}
 
 static void nvdimm_init(Object *obj)
 {
@@ -105,6 +128,11 @@ static void nvdimm_init(Object *obj)
 
     object_property_add(obj, NVDIMM_UUID_PROP, "QemuUUID", nvdimm_get_uuid,
                         nvdimm_set_uuid, NULL, NULL);
+
+    object_property_add(obj, NVDIMM_DEVICE_NODE, "uint8",
+                        nvdimm_get_device_node,
+                        nvdimm_set_device_node,
+                        NULL, NULL);
 }
 
 static void nvdimm_finalize(Object *obj)
diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
index bcf62f825c..430169322f 100644
--- a/include/hw/mem/nvdimm.h
+++ b/include/hw/mem/nvdimm.h
@@ -49,6 +49,7 @@
 OBJECT_DECLARE_TYPE(NVDIMMDevice, NVDIMMClass, NVDIMM)
 
 #define NVDIMM_LABEL_SIZE_PROP "label-size"
+#define NVDIMM_DEVICE_NODE  "device-node"
 #define NVDIMM_UUID_PROP       "uuid"
 #define NVDIMM_UNARMED_PROP    "unarmed"
 
@@ -89,6 +90,17 @@ struct NVDIMMDevice {
      * The PPC64 - spapr requires each nvdimm device have a uuid.
      */
     QemuUUID uuid;
+
+   /*
+    * The spapr-nvdimm (PPC64 NVDIMM) driver supports two modes of
+    * operation: regular memory and persistent memory. When using the
+    * device as regular memory, the NUMA nodeid that comes from
+    * PC_DIMM_NODEPROP is to be used. When used as persistent memory,
+    * the guest should consider the 'device-node' instead since it
+    * indicates the locality of the device to an established NUMA
+    * node, which is more relevant to this type of usage.
+    */
+    uint8_t device_node;
 };
 
 struct NVDIMMClass {
-- 
2.31.1