From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

Add the necessary plumbing for the hv-balloon driver to the PC machine.

Co-developed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 hw/i386/Kconfig |  1 +
 hw/i386/pc.c    | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index 94772c726b24..55850791df41 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -45,6 +45,7 @@ config PC
     select ACPI_VMGENID
     select VIRTIO_PMEM_SUPPORTED
     select VIRTIO_MEM_SUPPORTED
+    select HV_BALLOON_SUPPORTED
 
 config PC_PCI
     bool
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 6031234a73f1..1aef21aa2c25 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -27,6 +27,7 @@
 #include "hw/i386/pc.h"
 #include "hw/char/serial.h"
 #include "hw/char/parallel.h"
+#include "hw/hyperv/hv-balloon.h"
 #include "hw/i386/fw_cfg.h"
 #include "hw/i386/vmport.h"
 #include "sysemu/cpus.h"
@@ -57,6 +58,7 @@
 #include "hw/i386/kvm/xen_evtchn.h"
 #include "hw/i386/kvm/xen_gnttab.h"
 #include "hw/i386/kvm/xen_xenstore.h"
+#include "hw/mem/memory-device.h"
 #include "e820_memory_layout.h"
 #include "trace.h"
 #include CONFIG_DEVICES
@@ -1422,6 +1424,21 @@ static void pc_memory_unplug(HotplugHandler *hotplug_dev,
     error_propagate(errp, local_err);
 }
 
+static void pc_hv_balloon_pre_plug(HotplugHandler *hotplug_dev,
+                                   DeviceState *dev, Error **errp)
+{
+    /* The vmbus handler has no hotplug handler; we should never end up here. */
+    g_assert(!dev->hotplugged);
+    memory_device_pre_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev), NULL,
+                           errp);
+}
+
+static void pc_hv_balloon_plug(HotplugHandler *hotplug_dev,
+                               DeviceState *dev, Error **errp)
+{
+    memory_device_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
+}
+
 static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                           DeviceState *dev, Error **errp)
 {
@@ -1452,6 +1469,8 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
             return;
         }
         pcms->iommu = dev;
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON)) {
+        pc_hv_balloon_pre_plug(hotplug_dev, dev, errp);
     }
 }
 
@@ -1464,6 +1483,8 @@ static void pc_machine_device_plug_cb(HotplugHandler *hotplug_dev,
         x86_cpu_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
         virtio_md_pci_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON)) {
+        pc_hv_balloon_plug(hotplug_dev, dev, errp);
     }
 }
 
@@ -1505,6 +1526,7 @@ static HotplugHandler *pc_get_hotplug_handler(MachineState *machine,
         object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON) ||
         object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
         return HOTPLUG_HANDLER(machine);
     }