qmp: add hotplug memory

It adds size of MiB memory to the guest.

Signed-off-by: Peng Tao <bergwolf@gmail.com>

qemu/qmp.go

@@ -846,3 +846,38 @@ func (q *QMP) ExecSetMigrateArguments(ctx context.Context, url string) error {
 
 	return q.executeCommand(ctx, "migrate", args, nil)
 }
+
+// ExecHotplugMemory adds size of MiB memory to the guest
+func (q *QMP) ExecHotplugMemory(ctx context.Context, qomtype, id, mempath string, size int) error {
+	args := map[string]interface{}{
+		"qom-type": qomtype,
+		"id":       id,
+		"props":    map[string]interface{}{"size": uint64(size) << 20},
+	}
+	if mempath != "" {
+		args["mem-path"] = mempath
+	}
+	err := q.executeCommand(ctx, "object-add", args, nil)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		if err != nil {
+			q.cfg.Logger.Errorf("Unable to hotplug memory device: %v", err)
+			err = q.executeCommand(ctx, "object-del", map[string]interface{}{"id": id}, nil)
+			if err != nil {
+				q.cfg.Logger.Warningf("Unable to clean up memory object: %v", err)
+			}
+		}
+	}()
+
+	args = map[string]interface{}{
+		"driver": "pc-dimm",
+		"id":     "dimm" + id,
+		"memdev": id,
+	}
+	err = q.executeCommand(ctx, "device_add", args, nil)
+
+	return err
+}

qemu/qmp_test.go

@@ -927,3 +927,21 @@ func TestExecSetMigrateArguments(t *testing.T) {
 	q.Shutdown()
 	<-disconnectedCh
 }
+
+// Checks hotplug memory
+func TestExecHotplugMemory(t *testing.T) {
+	connectedCh := make(chan *QMPVersion)
+	disconnectedCh := make(chan struct{})
+	buf := newQMPTestCommandBuffer(t)
+	buf.AddCommand("object-add", nil, "return", nil)
+	buf.AddCommand("device_add", nil, "return", nil)
+	cfg := QMPConfig{Logger: qmpTestLogger{}}
+	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
+	checkVersion(t, connectedCh)
+	err := q.ExecHotplugMemory(context.Background(), "memory-backend-ram", "mem0", "", 128)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v\n", err)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}