qapi: Add HV_BALLOON_STATUS_REPORT event and its QMP query command

Used by the hv-balloon driver for (optional) guest memory status reports.

Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>

3 files changed, 49 insertions, 2 deletions

diff --git a/hw/hyperv/hv-balloon-stub.c b/hw/hyperv/hv-balloon-stub.c
new file mode 100644
index 0000000..a47412d
--- /dev/null
+++ b/hw/hyperv/hv-balloon-stub.c
@@ -0,0 +1,19 @@
+/*
+ * QEMU Hyper-V Dynamic Memory Protocol driver
+ *
+ * Copyright (C) 2023 Oracle and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-machine.h"
+#include "qapi/qapi-types-machine.h"
+
+HvBalloonInfo *qmp_query_hv_balloon_status_report(Error **errp)
+{
+    error_setg(errp, "hv-balloon device not enabled in this build");
+    return NULL;
+}
diff --git a/hw/hyperv/hv-balloon.c b/hw/hyperv/hv-balloon.c
index 44a8d15..66f297c 100644
--- a/hw/hyperv/hv-balloon.c
+++ b/hw/hyperv/hv-balloon.c
@@ -1102,7 +1102,35 @@ static void hv_balloon_handle_status_report(HvBalloon *balloon,
     balloon->status_report.available *= HV_BALLOON_PAGE_SIZE;
     balloon->status_report.received = true;
 
-    /* report event */
+    qapi_event_send_hv_balloon_status_report(balloon->status_report.committed,
+                                             balloon->status_report.available);
+}
+
+HvBalloonInfo *qmp_query_hv_balloon_status_report(Error **errp)
+{
+    HvBalloon *balloon;
+    HvBalloonInfo *info;
+
+    balloon = HV_BALLOON(object_resolve_path_type("", TYPE_HV_BALLOON, NULL));
+    if (!balloon) {
+        error_setg(errp, "no %s device present", TYPE_HV_BALLOON);
+        return NULL;
+    }
+
+    if (!balloon->status_report.enabled) {
+        error_setg(errp, "guest memory status reporting not enabled");
+        return NULL;
+    }
+
+    if (!balloon->status_report.received) {
+        error_setg(errp, "no guest memory status report received yet");
+        return NULL;
+    }
+
+    info = g_malloc0(sizeof(*info));
+    info->committed = balloon->status_report.committed;
+    info->available = balloon->status_report.available;
+    return info;
 }
 
 static void hv_balloon_handle_unballoon_response(HvBalloon *balloon,
diff --git a/hw/hyperv/meson.build b/hw/hyperv/meson.build
index 852d4f4..d3d2668 100644
--- a/hw/hyperv/meson.build
+++ b/hw/hyperv/meson.build
@@ -2,4 +2,4 @@ specific_ss.add(when: 'CONFIG_HYPERV', if_true: files('hyperv.c'))
 specific_ss.add(when: 'CONFIG_HYPERV_TESTDEV', if_true: files('hyperv_testdev.c'))
 specific_ss.add(when: 'CONFIG_VMBUS', if_true: files('vmbus.c'))
 specific_ss.add(when: 'CONFIG_SYNDBG', if_true: files('syndbg.c'))
-specific_ss.add(when: 'CONFIG_HV_BALLOON', if_true: files('hv-balloon.c', 'hv-balloon-page_range_tree.c', 'hv-balloon-our_range_memslots.c'))
+specific_ss.add(when: 'CONFIG_HV_BALLOON', if_true: files('hv-balloon.c', 'hv-balloon-page_range_tree.c', 'hv-balloon-our_range_memslots.c'), if_false: files('hv-balloon-stub.c'))