[PATCH v2 09/11] hw/xenpv: Restrict Xen Para-virtualized machine to Xen accelerator

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

When started with other accelerator than Xen, the XenPV machine
fails with a criptic message:

  $ qemu-system-x86_64 -M xenpv,accel=kvm
  xen be core: can't connect to xenstored
  qemu-system-x86_64: xen_init_pv: xen backend core setup failed

By restricting it to Xen, we display a clearer error message:

  $ qemu-system-x86_64 -M xenpv,accel=kvm
  qemu-system-x86_64: invalid accelerator 'kvm' for machine xenpv

Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
---
 hw/xenpv/xen_machine_pv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
index 8df575a457c..d7747bcec98 100644
--- a/hw/xenpv/xen_machine_pv.c
+++ b/hw/xenpv/xen_machine_pv.c
@@ -86,12 +86,17 @@ static void xen_init_pv(MachineState *machine)
     atexit(xen_config_cleanup);
 }
 
+static const char *valid_accels[] = {
+    "xen", NULL
+};
+
 static void xenpv_machine_init(MachineClass *mc)
 {
     mc->desc = "Xen Para-virtualized PC";
     mc->init = xen_init_pv;
     mc->max_cpus = 1;
     mc->default_machine_opts = "accel=xen";
+    mc->valid_accelerators = valid_accels;
 }
 
 DEFINE_MACHINE("xenpv", xenpv_machine_init)
-- 
2.26.2