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[RFC PATCH] hw/virtio: rename vhost-user-device and make user creatable

Alex Bennée posted 1 patch 3 months, 3 weeks ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20250820195632.1956795-1-alex.bennee@linaro.org
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
There is a newer version of this series
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%)
[RFC PATCH] hw/virtio: rename vhost-user-device and make user creatable
Posted by Alex Bennée 3 months, 3 weeks ago 
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.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 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
Re: [RFC PATCH] hw/virtio: rename vhost-user-device and make user creatable
Posted by Stefano Garzarella 3 months, 2 weeks ago 
On Wed, Aug 20, 2025 at 08:56:32PM +0100, Alex Bennée wrote:
>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

FYI I just crated this issue https://github.com/rust-vmm/vhost-device/issues/868
since in some device's README we suggest to use `-device 
vhost-user-device-pci` with QEMU (without specifing to patch QEMU to 
enable them). That said, I guess this patch is fine.
I think we can just update the README and suggest to use a new version 
of QEMU.

>Kconfig variable so it can be skipped for those that want to thin out
>their build configuration even further.
>
>Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>---
> 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%)

Acked-by: Stefano Garzarella <sgarzare@redhat.com>

Thanks,
Stefano

>
>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
>
Re: [RFC PATCH] hw/virtio: rename vhost-user-device and make user creatable
Posted by Manos Pitsidianakis 3 months, 3 weeks ago 
On Wed, Aug 20, 2025 at 10:57 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>
> 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.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>

>  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
>
>

-- 
Manos Pitsidianakis
Emulation and Virtualization Engineer at Linaro Ltd
Re: [RFC PATCH] hw/virtio: rename vhost-user-device and make user creatable
Posted by Stefan Hajnoczi 3 months, 3 weeks ago 
On Wed, Aug 20, 2025 at 08:56:32PM +0100, Alex Bennée wrote:
> 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.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>  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%)

It's okay to rename this device since no one today can use
vhost-user-device without modifying QEMU's source code anyway.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Patchew 2.1-devel-b67e4c2

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