hw/arm/virt: Add a user option to disallow ITS instantiation

In 2.9 ITS will block save/restore and migration use cases. As such,
let's introduce a user option that allows to turn its instantiation
off, along with GICv3. With the "its" option turned false, migration
will be possible, obviously at the expense of MSI support (with GICv3).
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Message-id: 1487681108-14452-1-git-send-email-eric.auger@redhat.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/arm/virt.c

@@ -535,7 +535,6 @@ static void create_v2m(VirtMachineState *vms, qemu_irq *pic)
 static void create_gic(VirtMachineState *vms, qemu_irq *pic)
 {
     /* We create a standalone GIC */
-    VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
     DeviceState *gicdev;
     SysBusDevice *gicbusdev;
     const char *gictype;
@@ -605,7 +604,7 @@ static void create_gic(VirtMachineState *vms, qemu_irq *pic)
 
     fdt_add_gic_node(vms);
 
-    if (type == 3 && !vmc->no_its) {
+    if (type == 3 && vms->its) {
         create_its(vms, gicdev);
     } else if (type == 2) {
         create_v2m(vms, pic);
@@ -1481,6 +1480,20 @@ static void virt_set_highmem(Object *obj, bool value, Error **errp)
     vms->highmem = value;
 }
 
+static bool virt_get_its(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->its;
+}
+
+static void virt_set_its(Object *obj, bool value, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->its = value;
+}
+
 static char *virt_get_gic_version(Object *obj, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
@@ -1541,6 +1554,7 @@ type_init(machvirt_machine_init);
 static void virt_2_9_instance_init(Object *obj)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
+    VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
 
     /* EL3 is disabled by default on virt: this makes us consistent
      * between KVM and TCG for this board, and it also allows us to
@@ -1580,6 +1594,19 @@ static void virt_2_9_instance_init(Object *obj)
                                     "Set GIC version. "
                                     "Valid values are 2, 3 and host", NULL);
 
+    if (vmc->no_its) {
+        vms->its = false;
+    } else {
+        /* Default allows ITS instantiation */
+        vms->its = true;
+        object_property_add_bool(obj, "its", virt_get_its,
+                                 virt_set_its, NULL);
+        object_property_set_description(obj, "its",
+                                        "Set on/off to enable/disable "
+                                        "ITS instantiation",
+                                        NULL);
+    }
+
     vms->memmap = a15memmap;
     vms->irqmap = a15irqmap;
 }

include/hw/arm/virt.h

@@ -93,6 +93,7 @@ typedef struct {
     FWCfgState *fw_cfg;
     bool secure;
     bool highmem;
+    bool its;
     bool virt;
     int32_t gic_version;
     struct arm_boot_info bootinfo;