hw/acpi/vmgenid: prevent more than one vmgenid device

A system with multiple VMGENID devices is undefined in the VMGENID spec by
omission.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Ben Warren <ben@skyportsystems.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
index c3ddcc8e7c..a32b847fe0 100644
--- a/hw/acpi/vmgenid.c
+++ b/hw/acpi/vmgenid.c
@@ -221,6 +221,14 @@ static void vmgenid_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    /* Given that this function is executing, there is at least one VMGENID
+     * device. Check if there are several.
+     */
+    if (!find_vmgenid_dev()) {
+        error_setg(errp, "at most one %s device is permitted", VMGENID_DEVICE);
+        return;
+    }
+
     qemu_register_reset(vmgenid_handle_reset, vms);
 }