[PATCH v1 10/15] pc-dimm: Provide pc_dimm_get_free_slots() to query free ram slots

[David Hildenbrand <david@redhat.com>]

memory device wants to figure out at per-device memslot limit for memory
devices that want to consume more than a single memslot. We want to try
setting the memslots required for DIMMs/NVDIMMs (1 memslot per such device)
aside, so expose how many of these slots are still free.

Keep it simple and place the stub into qmp_memory_device.c.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/mem/pc-dimm.c          | 27 +++++++++++++++++++++++++++
 include/hw/mem/pc-dimm.h  |  1 +
 stubs/qmp_memory_device.c |  6 ++++++
 3 files changed, 34 insertions(+)

diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 37f1f4ccfd..64ee0c38c0 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -152,6 +152,33 @@ out:
     return slot;
 }
 
+static int pc_dimm_count_slots(Object *obj, void *opaque)
+{
+    unsigned int *slots = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
+        DeviceState *dev = DEVICE(obj);
+        if (dev->realized) { /* count only realized DIMMs */
+            (*slots)++;
+        }
+    }
+    return 0;
+}
+
+unsigned int pc_dimm_get_free_slots(MachineState *machine)
+{
+    const unsigned int max_slots = machine->ram_slots;
+    unsigned int slots = 0;
+
+    if (!max_slots) {
+        return 0;
+    }
+
+    object_child_foreach_recursive(OBJECT(machine), pc_dimm_count_slots,
+                                   &slots);
+    return max_slots - slots;
+}
+
 static Property pc_dimm_properties[] = {
     DEFINE_PROP_UINT64(PC_DIMM_ADDR_PROP, PCDIMMDevice, addr, 0),
     DEFINE_PROP_UINT32(PC_DIMM_NODE_PROP, PCDIMMDevice, node, 0),
diff --git a/include/hw/mem/pc-dimm.h b/include/hw/mem/pc-dimm.h
index 322bebe555..60051ac753 100644
--- a/include/hw/mem/pc-dimm.h
+++ b/include/hw/mem/pc-dimm.h
@@ -70,4 +70,5 @@ void pc_dimm_pre_plug(PCDIMMDevice *dimm, MachineState *machine,
                       const uint64_t *legacy_align, Error **errp);
 void pc_dimm_plug(PCDIMMDevice *dimm, MachineState *machine);
 void pc_dimm_unplug(PCDIMMDevice *dimm, MachineState *machine);
+unsigned int pc_dimm_get_free_slots(MachineState *machine);
 #endif
diff --git a/stubs/qmp_memory_device.c b/stubs/qmp_memory_device.c
index 74707ed9fd..7022bd188b 100644
--- a/stubs/qmp_memory_device.c
+++ b/stubs/qmp_memory_device.c
@@ -1,5 +1,6 @@
 #include "qemu/osdep.h"
 #include "hw/mem/memory-device.h"
+#include "hw/mem/pc-dimm.h"
 
 MemoryDeviceInfoList *qmp_memory_device_list(void)
 {
@@ -19,3 +20,8 @@ unsigned int memory_devices_get_reserved_memslots(void)
 {
     return 0;
 }
+
+unsigned int pc_dimm_get_free_slots(MachineState *machine)
+{
+    return 0;
+}
-- 
2.40.1