[Qemu-devel] [PATCH 10/11] pc: explicitly check maxmem limit when adding DIMM

[Igor Mammedov <imammedo@redhat.com>]

Currently maxmem limit is not checked and depends on
hotplug region container not being able to fit more RAM
than maxmem. Do check explicitly so that it would
be possible to change hotplug container size later
to deal with fragmentation.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/i386/pc.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index ed50344..0d9681e 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1586,6 +1586,25 @@ void qemu_register_pc_machine(QEMUMachine *m)
     g_free(name);
 }
 
+static int pc_existing_dimms_capacity(Object *obj, void *opaque)
+{
+    Error *local_err = NULL;
+    uint64_t *size = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
+        (*size) += object_property_get_int(obj, PC_DIMM_SIZE_PROP, &local_err);
+
+        if (local_err) {
+            qerror_report_err(local_err);
+            error_free(local_err);
+            return 1;
+        }
+    }
+
+    object_child_foreach(obj, pc_dimm_count, opaque);
+    return 0;
+}
+
 static void pc_dimm_plug(HotplugHandler *hotplug_dev,
                          DeviceState *dev, Error **errp)
 {
@@ -1597,6 +1616,7 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
     PCDIMMDevice *dimm = PC_DIMM(dev);
     PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
     MemoryRegion *mr = ddc->get_memory_region(dimm);
+    uint64_t existing_dimms_capacity = 0;
     uint64_t align = TARGET_PAGE_SIZE;
     uint64_t addr;
 
@@ -1617,6 +1637,19 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
         goto out;
     }
 
+    if (pc_existing_dimms_capacity(OBJECT(machine), &existing_dimms_capacity)) {
+        error_setg(&local_err, "failed to get total size of existing DIMMs");
+        goto out;
+    }
+
+    if (existing_dimms_capacity + memory_region_size(mr) >
+        machine->maxram_size - machine->ram_size) {
+        error_setg(&local_err, "not enough space, currently 0x%" PRIx64
+                   " in use of total 0x%" PRIx64,
+                   existing_dimms_capacity, machine->maxram_size);
+        goto out;
+    }
+
     object_property_set_int(OBJECT(dev), addr, PC_DIMM_ADDR_PROP, &local_err);
     if (local_err) {
         goto out;
-- 
1.8.3.1