We didn't make the device user creatable in the first place because we
were worried users might get confused. Rename the device to make its
nature as a test device even more explicit. While we are at it add a
Kconfig variable so it can be skipped for those that want to thin out
their build configuration even further.

Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-ID: <20250820195632.1956795-1-alex.bennee@linaro.org>

---
v2
  - add review tags, ready to merge
---
 docs/system/devices/vhost-user.rst            | 20 +++++++------------
 include/hw/virtio/vhost-user-base.h           |  2 +-
 ...ice-pci.c => vhost-user-test-device-pci.c} | 17 +++++++---------
 ...user-device.c => vhost-user-test-device.c} |  9 +++------
 hw/virtio/Kconfig                             |  5 +++++
 hw/virtio/meson.build                         |  5 +++--
 6 files changed, 26 insertions(+), 32 deletions(-)
 rename hw/virtio/{vhost-user-device-pci.c => vhost-user-test-device-pci.c} (77%)
 rename hw/virtio/{vhost-user-device.c => vhost-user-test-device.c} (87%)

diff --git a/docs/system/devices/vhost-user.rst b/docs/system/devices/vhost-user.rst
index 35259d8ec7c..bddf8df5ed5 100644
--- a/docs/system/devices/vhost-user.rst
+++ b/docs/system/devices/vhost-user.rst
@@ -62,26 +62,20 @@ platform details for what sort of virtio bus to use.
 The referenced *daemons* are not exhaustive, any conforming backend
 implementing the device and using the vhost-user protocol should work.
 
-vhost-user-device
-^^^^^^^^^^^^^^^^^
+vhost-user-test-device
+^^^^^^^^^^^^^^^^^^^^^^
 
-The vhost-user-device is a generic development device intended for
-expert use while developing new backends. The user needs to specify
-all the required parameters including:
+The vhost-user-test-device is a generic development device intended
+for expert use while developing new backends. The user needs to
+specify all the required parameters including:
 
   - Device ``virtio-id``
   - The ``num_vqs`` it needs and their ``vq_size``
   - The ``config_size`` if needed
 
 .. note::
-  To prevent user confusion you cannot currently instantiate
-  vhost-user-device without first patching out::
-
-    /* Reason: stop inexperienced users confusing themselves */
-    dc->user_creatable = false;
-
-  in ``vhost-user-device.c`` and ``vhost-user-device-pci.c`` file and
-  rebuilding.
+  While this is a useful device for development it is not recommended
+  for production use.
 
 vhost-user daemon
 =================
diff --git a/include/hw/virtio/vhost-user-base.h b/include/hw/virtio/vhost-user-base.h
index 51d0968b893..387e434b804 100644
--- a/include/hw/virtio/vhost-user-base.h
+++ b/include/hw/virtio/vhost-user-base.h
@@ -44,6 +44,6 @@ struct VHostUserBaseClass {
 };
 
 
-#define TYPE_VHOST_USER_DEVICE "vhost-user-device"
+#define TYPE_VHOST_USER_TEST_DEVICE "vhost-user-test-device"
 
 #endif /* QEMU_VHOST_USER_BASE_H */
diff --git a/hw/virtio/vhost-user-device-pci.c b/hw/virtio/vhost-user-test-device-pci.c
similarity index 77%
rename from hw/virtio/vhost-user-device-pci.c
rename to hw/virtio/vhost-user-test-device-pci.c
index f10bac874e7..d6a9ca2101d 100644
--- a/hw/virtio/vhost-user-device-pci.c
+++ b/hw/virtio/vhost-user-test-device-pci.c
@@ -18,13 +18,13 @@ struct VHostUserDevicePCI {
     VHostUserBase vub;
 };
 
-#define TYPE_VHOST_USER_DEVICE_PCI "vhost-user-device-pci-base"
+#define TYPE_VHOST_USER_TEST_DEVICE_PCI "vhost-user-test-device-pci"
 
-OBJECT_DECLARE_SIMPLE_TYPE(VHostUserDevicePCI, VHOST_USER_DEVICE_PCI)
+OBJECT_DECLARE_SIMPLE_TYPE(VHostUserDevicePCI, VHOST_USER_TEST_DEVICE_PCI)
 
 static void vhost_user_device_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
 {
-    VHostUserDevicePCI *dev = VHOST_USER_DEVICE_PCI(vpci_dev);
+    VHostUserDevicePCI *dev = VHOST_USER_TEST_DEVICE_PCI(vpci_dev);
     DeviceState *vdev = DEVICE(&dev->vub);
 
     vpci_dev->nvectors = 1;
@@ -38,9 +38,6 @@ static void vhost_user_device_pci_class_init(ObjectClass *klass,
     VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
     PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
 
-    /* Reason: stop users confusing themselves */
-    dc->user_creatable = false;
-
     k->realize = vhost_user_device_pci_realize;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
     pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
@@ -51,15 +48,15 @@ static void vhost_user_device_pci_class_init(ObjectClass *klass,
 
 static void vhost_user_device_pci_instance_init(Object *obj)
 {
-    VHostUserDevicePCI *dev = VHOST_USER_DEVICE_PCI(obj);
+    VHostUserDevicePCI *dev = VHOST_USER_TEST_DEVICE_PCI(obj);
 
     virtio_instance_init_common(obj, &dev->vub, sizeof(dev->vub),
-                                TYPE_VHOST_USER_DEVICE);
+                                TYPE_VHOST_USER_TEST_DEVICE);
 }
 
 static const VirtioPCIDeviceTypeInfo vhost_user_device_pci_info = {
-    .base_name = TYPE_VHOST_USER_DEVICE_PCI,
-    .non_transitional_name = "vhost-user-device-pci",
+    .base_name = TYPE_VHOST_USER_TEST_DEVICE_PCI,
+    .non_transitional_name = "vhost-user-test-device-pci",
     .instance_size = sizeof(VHostUserDevicePCI),
     .instance_init = vhost_user_device_pci_instance_init,
     .class_init = vhost_user_device_pci_class_init,
diff --git a/hw/virtio/vhost-user-device.c b/hw/virtio/vhost-user-test-device.c
similarity index 87%
rename from hw/virtio/vhost-user-device.c
rename to hw/virtio/vhost-user-test-device.c
index 3939bdf7552..1b98ea3e488 100644
--- a/hw/virtio/vhost-user-device.c
+++ b/hw/virtio/vhost-user-test-device.c
@@ -1,5 +1,5 @@
 /*
- * Generic vhost-user-device implementation for any vhost-user-backend
+ * Generic vhost-user-test-device implementation for any vhost-user-backend
  *
  * This is a concrete implementation of vhost-user-base which can be
  * configured via properties. It is useful for development and
@@ -25,7 +25,7 @@
  */
 
 static const VMStateDescription vud_vmstate = {
-    .name = "vhost-user-device",
+    .name = "vhost-user-test-device",
     .unmigratable = 1,
 };
 
@@ -41,16 +41,13 @@ static void vud_class_init(ObjectClass *klass, const void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
-    /* Reason: stop inexperienced users confusing themselves */
-    dc->user_creatable = false;
-
     device_class_set_props(dc, vud_properties);
     dc->vmsd = &vud_vmstate;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 }
 
 static const TypeInfo vud_info = {
-    .name = TYPE_VHOST_USER_DEVICE,
+    .name = TYPE_VHOST_USER_TEST_DEVICE,
     .parent = TYPE_VHOST_USER_BASE,
     .class_init = vud_class_init,
 };
diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
index 7648a2d68da..10f5c53ac09 100644
--- a/hw/virtio/Kconfig
+++ b/hw/virtio/Kconfig
@@ -126,3 +126,8 @@ config VHOST_USER_SCMI
     bool
     default y
     depends on VIRTIO && VHOST_USER && ARM
+
+config VHOST_USER_TEST
+    bool
+    default y
+    depends on VIRTIO && VHOST_USER
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index 3ea7b3cec83..48b9fedfa56 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -22,7 +22,7 @@ if have_vhost
     system_virtio_ss.add(files('vhost-user-base.c'))
 
     # MMIO Stubs
-    system_virtio_ss.add(files('vhost-user-device.c'))
+    system_virtio_ss.add(when: 'CONFIG_VHOST_USER_TEST', if_true: files('vhost-user-test-device.c'))
     system_virtio_ss.add(when: 'CONFIG_VHOST_USER_GPIO', if_true: files('vhost-user-gpio.c'))
     system_virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
     system_virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user-rng.c'))
@@ -30,7 +30,8 @@ if have_vhost
     system_virtio_ss.add(when: 'CONFIG_VHOST_USER_INPUT', if_true: files('vhost-user-input.c'))
 
     # PCI Stubs
-    system_virtio_ss.add(when: 'CONFIG_VIRTIO_PCI', if_true: files('vhost-user-device-pci.c'))
+    system_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_TEST'],
+                         if_true: files('vhost-user-test-device-pci.c'))
     system_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_GPIO'],
                          if_true: files('vhost-user-gpio-pci.c'))
     system_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_I2C'],
-- 
2.47.2

Alex Bennée <alex.bennee@linaro.org> writes:

> We didn't make the device user creatable in the first place because we
> were worried users might get confused. Rename the device to make its
> nature as a test device even more explicit. While we are at it add a
> Kconfig variable so it can be skipped for those that want to thin out
> their build configuration even further.
>
> Acked-by: Stefano Garzarella <sgarzare@redhat.com>
> Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Message-ID: <20250820195632.1956795-1-alex.bennee@linaro.org>
>
<snip>
> --- a/hw/virtio/vhost-user-device-pci.c
> +++ b/hw/virtio/vhost-user-test-device-pci.c
> @@ -18,13 +18,13 @@ struct VHostUserDevicePCI {
>      VHostUserBase vub;
>  };
>  
> -#define TYPE_VHOST_USER_DEVICE_PCI "vhost-user-device-pci-base"
> +#define TYPE_VHOST_USER_TEST_DEVICE_PCI "vhost-user-test-device-pci"

oops dropping the -base here broke:

>  
>  static const VirtioPCIDeviceTypeInfo vhost_user_device_pci_info = {
> -    .base_name = TYPE_VHOST_USER_DEVICE_PCI,
> -    .non_transitional_name = "vhost-user-device-pci",
> +    .base_name = TYPE_VHOST_USER_TEST_DEVICE_PCI,
> +    .non_transitional_name = "vhost-user-test-device-pci",
>      .instance_size = sizeof(VHostUserDevicePCI),
>      .instance_init = vhost_user_device_pci_instance_init,
>      .class_init = vhost_user_device_pci_class_init,
<snip>

the checking here. So I have sent v2:

  Subject: [PATCH v2] hw/virtio: rename vhost-user-device and make user creatable
  Date: Mon,  1 Sep 2025 11:59:48 +0100
  Message-ID: <20250901105948.982583-1-alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro