[Qemu-devel] [PATCH 2/2] nvdimm: disable balloon

[Denis V. Lunev]

From: Vladimir Sementsov-Ogievskiy <address@hidden>

NVDIMM for now is planned to use as a backing store for DAX filesystem
in the guest and thus this memory is excluded from guest memory
management
and LRUs.

In this case libvirt running QEMU along with configured balloon almost
immediately inflates balloon and effectively kill the guest as
qemu counts nvdimm as part of the ram.

Counting dimm devices as part of the ram for ballooning was started from
commit 463756d03:
 virtio-balloon: Fix balloon not working correctly when hotplug memory

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
CC: Xiao Guangrong <address@hidden>
CC: "Michael S. Tsirkin" <address@hidden>
CC: Igor Mammedov <address@hidden>
CC: Eric Blake <address@hidden>
CC: Markus Armbruster <address@hidden>
---
 hw/mem/pc-dimm.c           | 2 ++
 hw/virtio/virtio-balloon.c | 4 +++-
 qapi-schema.json           | 5 ++++-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 4f30950..2ff9f95 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -19,6 +19,7 @@
  */
 
 #include "hw/mem/pc-dimm.h"
+#include "hw/mem/nvdimm.h"
 #include "qemu/config-file.h"
 #include "qapi/visitor.h"
 #include "qemu/range.h"
@@ -178,6 +179,7 @@ int qmp_pc_dimm_device_list(Object *obj, void *opaque)
             di->size = object_property_get_int(OBJECT(dimm), PC_DIMM_SIZE_PROP,
                                                NULL);
             di->memdev = object_get_canonical_path(OBJECT(dimm->hostmem));
+            di->balloonable = (object_dynamic_cast(obj, TYPE_NVDIMM) == NULL);
 
             info->u.dimm = di;
             elem->value = info;
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 6a4c4d2..0a3de75 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -308,7 +308,9 @@ static ram_addr_t get_current_ram_size(void)
         if (value) {
             switch (value->type) {
             case MEMORY_DEVICE_INFO_KIND_DIMM:
-                size += value->u.dimm->size;
+                if (value->u.dimm->balloonable) {
+                    size += value->u.dimm->size;
+                }
                 break;
             default:
                 break;
diff --git a/qapi-schema.json b/qapi-schema.json
index 8d04897..5934f81 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3924,6 +3924,8 @@
 #
 # @hotpluggable: true if device if could be added/removed while machine is 
running
 #
+# @balloonable: true if device take part in ballooning (since 2.6)
+#
 # Since: 2.1
 ##
 { 'struct': 'PCDIMMDeviceInfo',
@@ -3934,7 +3936,8 @@
             'node': 'int',
             'memdev': 'str',
             'hotplugged': 'bool',
-            'hotpluggable': 'bool'
+            'hotpluggable': 'bool',
+            'balloonable': 'bool'
           }
 }
 
-- 
2.5.0