pc: explicitly check maxmem limit when adding DIMM

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>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 021ec44..3d732cf 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1545,6 +1545,37 @@ void qemu_register_pc_machine(QEMUMachine *m)
     g_free(name);
 }
 
+static int pc_dimm_count(Object *obj, void *opaque)
+{
+    int *count = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
+        (*count)++;
+    }
+
+    object_child_foreach(obj, pc_dimm_count, opaque);
+    return 0;
+}
+
+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)
 {
@@ -1556,6 +1587,7 @@ 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;
 
@@ -1576,6 +1608,19 @@ 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" RAM_ADDR_FMT,
+                   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;