[PATCH v3 17/20] virtio-pci: Send qapi events when the virtio-mem size changes

David Hildenbrand
2020-06-03T14:50:55Z

Let's register the notifier and trigger the qapi event with the right
device id.

MEMORY_DEVICE_SIZE_CHANGE is similar to BALLOON_CHANGE, however on a
memory device level.

Don't unregister the notifier (we neither have finalize() nor unrealize()
for VirtIOPCIProxy, so it's not that simple to do it) - both devices are
expected to vanish at the same time.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
hw/virtio/virtio-mem-pci.c | 28 ++++++++++++++++++++++++++++
hw/virtio/virtio-mem-pci.h | 1 +
monitor/monitor.c | 1 +
qapi/misc.json | 25 +++++++++++++++++++++++++
4 files changed, 55 insertions(+)

diff --git a/hw/virtio/virtio-mem-pci.c b/hw/virtio/virtio-mem-pci.c
index b325303b32..1a8e854123 100644
--- a/hw/virtio/virtio-mem-pci.c
+++ b/hw/virtio/virtio-mem-pci.c
@@ -14,6 +14,7 @@
#include "virtio-mem-pci.h"
#include "hw/mem/memory-device.h"
#include "qapi/error.h"
+#include "qapi/qapi-events-misc.h"

static void virtio_mem_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
{
@@ -74,6 +75,21 @@ static void virtio_mem_pci_fill_device_info(const MemoryDeviceState *md,
info->type = MEMORY_DEVICE_INFO_KIND_VIRTIO_MEM;
}

+static void virtio_mem_pci_size_change_notify(Notifier *notifier, void *data)
+{
+ VirtIOMEMPCI *pci_mem = container_of(notifier, VirtIOMEMPCI,
+ size_change_notifier);
+ DeviceState *dev = DEVICE(pci_mem);
+ const uint64_t * const size_p = data;
+ const char *id = NULL;
+
+ if (dev->id) {
+ id = g_strdup(dev->id);
+ }
+
+ qapi_event_send_memory_device_size_change(!!id, id, *size_p);
+}
+
static void virtio_mem_pci_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -98,9 +114,21 @@ static void virtio_mem_pci_class_init(ObjectClass *klass, void *data)
static void virtio_mem_pci_instance_init(Object *obj)
{
VirtIOMEMPCI *dev = VIRTIO_MEM_PCI(obj);
+ VirtIOMEMClass *vmc;
+ VirtIOMEM *vmem;

virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
TYPE_VIRTIO_MEM);
+
+ dev->size_change_notifier.notify = virtio_mem_pci_size_change_notify;
+ vmem = VIRTIO_MEM(&dev->vdev);
+ vmc = VIRTIO_MEM_GET_CLASS(vmem);
+ /*
+ * We never remove the notifier again, as we expect both devices to
+ * disappear at the same time.
+ */
+ vmc->add_size_change_notifier(vmem, &dev->size_change_notifier);
+
object_property_add_alias(obj, VIRTIO_MEM_BLOCK_SIZE_PROP,
OBJECT(&dev->vdev), VIRTIO_MEM_BLOCK_SIZE_PROP);
object_property_add_alias(obj, VIRTIO_MEM_SIZE_PROP, OBJECT(&dev->vdev),
diff --git a/hw/virtio/virtio-mem-pci.h b/hw/virtio/virtio-mem-pci.h
index 8820cd6628..b51a28b275 100644
--- a/hw/virtio/virtio-mem-pci.h
+++ b/hw/virtio/virtio-mem-pci.h
@@ -28,6 +28,7 @@ typedef struct VirtIOMEMPCI VirtIOMEMPCI;
struct VirtIOMEMPCI {
VirtIOPCIProxy parent_obj;
VirtIOMEM vdev;
+ Notifier size_change_notifier;
};

#endif /* QEMU_VIRTIO_MEM_PCI_H */
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 125494410a..19dcb8fbe3 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -235,6 +235,7 @@ static MonitorQAPIEventConf monitor_qapi_event_conf[QAPI_EVENT__MAX] = {
[QAPI_EVENT_QUORUM_REPORT_BAD] = { 1000 * SCALE_MS },
[QAPI_EVENT_QUORUM_FAILURE] = { 1000 * SCALE_MS },
[QAPI_EVENT_VSERPORT_CHANGE] = { 1000 * SCALE_MS },
+ [QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE] = { 1000 * SCALE_MS },
};

/*
diff --git a/qapi/misc.json b/qapi/misc.json
index e1c5547b65..4b25daeadb 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -1432,6 +1432,31 @@
##
{ 'command': 'query-memory-devices', 'returns': ['MemoryDeviceInfo'] }

+##
+# @MEMORY_DEVICE_SIZE_CHANGE:
+#
+# Emitted when the size of a memory device changes. Only emitted for memory
+# devices that can actually change the size (e.g., virtio-mem due to guest
+# action).
+#
+# @id: device's ID
+# @size: the new size of memory that the device provides
+#
+# Note: this event is rate-limited.
+#
+# Since: 5.1
+#
+# Example:
+#
+# <- { "event": "MEMORY_DEVICE_SIZE_CHANGE",
+# "data": { "id": "vm0", "size": 1073741824},
+# "timestamp": { "seconds": 1588168529, "microseconds": 201316 } }
+#
+##
+{ 'event': 'MEMORY_DEVICE_SIZE_CHANGE',
+ 'data': { '*id': 'str', 'size': 'size' } }
+
+
##
# @MEM_UNPLUG_ERROR:
#
--
2.25.4