From: Bruce Rogers <brogers@suse.com>
Date: Thu, 21 Jan 2021 16:34:32 -0700
Subject: module: for virtio-gpu, pre-load module to avoid abort on missing
 module

If the hw-display-virtio-gpu module is not loadable when the virtio-gpu
device is on the command line or being added in monitor, qemu will call
abort. We can fail gracefully by doing the module load in a context
which is set up to handle errors properly. (bsc#1181103)

Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 include/qemu/module.h  |  1 +
 qom/object.c           | 12 ++++++++++++
 softmmu/qdev-monitor.c | 15 +++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/include/qemu/module.h b/include/qemu/module.h
index 944d403cbd1535cc121af76a94f2..4b42dd285eeac1ba12e5c9e18ac0 100644
--- a/include/qemu/module.h
+++ b/include/qemu/module.h
@@ -72,5 +72,6 @@ void module_call_init(module_init_type type);
 bool module_load_one(const char *prefix, const char *lib_name, bool mayfail);
 void module_load_qom_one(const char *type);
 void module_load_qom_all(void);
+int module_load_check(const char *name);
 
 #endif
diff --git a/qom/object.c b/qom/object.c
index 10653552334549241cd5672d7a02..6f301fec34d103b0b07bc41d107c 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -516,6 +516,18 @@ static void object_initialize_with_type(Object *obj, size_t size, TypeImpl *type
     object_post_init_with_type(obj, type);
 }
 
+#ifdef CONFIG_MODULES
+int module_load_check(const char *name)
+{
+    TypeImpl *type = type_get_by_name(name);
+    if (!type) {
+        module_load_qom_one(name);
+        type = type_get_by_name(name);
+    }
+    return type == NULL;
+}
+#endif
+
 void object_initialize(void *data, size_t size, const char *typename)
 {
     TypeImpl *type = type_get_by_name(typename);
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index bf79d0bbcd986320eb609f37253e..564dfaeeda9c3ae9dbf1afa97825 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -263,6 +263,13 @@ int qdev_device_help(QemuOpts *opts)
     int i;
 
     driver = qemu_opt_get(opts, "driver");
+#ifdef CONFIG_MODULES
+    if (driver && !strcmp(driver, "virtio-gpu")) {
+        if (module_load_check("virtio-gpu-device")) {
+            return 0;
+        }
+    }
+#endif
     if (driver && is_help_option(driver)) {
         qdev_print_devinfos(false);
         return 1;
@@ -650,6 +657,14 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
         return NULL;
     }
 
+#ifdef CONFIG_MODULES
+    if (!strcmp(driver, "virtio-gpu-pci") || !strcmp(driver, "virtio-gpu-ccw")) {
+        if (module_load_check("virtio-gpu-device")) {
+            error_setg(errp, "loadable module for %s not available!", driver);
+            return NULL;
+        }
+    }
+#endif
     /* create device */
     dev = qdev_new(driver);