s390x: modularize virtio-gpu-ccw

Since the virtio-gpu-ccw device depends on the hw-display-virtio-gpu
module, which provides the type virtio-gpu-device, packaging the
hw-display-virtio-gpu module as a separate package that may or may not
be installed along with the qemu package leads to problems. Namely if
the hw-display-virtio-gpu is absent, qemu continues to advertise
virtio-gpu-ccw, but it aborts not only when one attempts using
virtio-gpu-ccw, but also when libvirtd's capability probing tries
to instantiate the type to introspect it.

Let us thus introduce a module named hw-s390x-virtio-gpu-ccw that
is going to provide the virtio-gpu-ccw device. The hw-s390x prefix
was chosen because it is not a portable device.

With virtio-gpu-ccw built as a module, the correct way to package a
modularized qemu is to require that hw-display-virtio-gpu must be
installed whenever the module hw-s390x-virtio-gpu-ccw.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Halil Pasic <pasic@linux.ibm.com>
Message-Id: <20210317095622.2839895-4-kraxel@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Author: kraxel

hw/s390x/meson.build

@@ -34,7 +34,6 @@ virtio_ss.add(files('virtio-ccw.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_BALLOON', if_true: files('virtio-ccw-balloon.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true: files('virtio-ccw-blk.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('virtio-ccw-crypto.c'))
-virtio_ss.add(when: 'CONFIG_VIRTIO_GPU', if_true: files('virtio-ccw-gpu.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_INPUT', if_true: files('virtio-ccw-input.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_NET', if_true: files('virtio-ccw-net.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-ccw-rng.c'))
@@ -48,3 +47,10 @@ virtio_ss.add(when: 'CONFIG_VHOST_USER_FS', if_true: files('vhost-user-fs-ccw.c'
 s390x_ss.add_all(when: 'CONFIG_VIRTIO_CCW', if_true: virtio_ss)
 
 hw_arch += {'s390x': s390x_ss}
+
+hw_s390x_modules = {}
+virtio_gpu_ccw_ss = ss.source_set()
+virtio_gpu_ccw_ss.add(when: ['CONFIG_VIRTIO_GPU', 'CONFIG_VIRTIO_CCW'],
+                      if_true: [files('virtio-ccw-gpu.c'), pixman])
+hw_s390x_modules += {'virtio-gpu-ccw': virtio_gpu_ccw_ss}
+modules += {'hw-s390x': hw_s390x_modules}

hw/s390x/virtio-ccw-gpu.c

@@ -62,7 +62,9 @@ static const TypeInfo virtio_ccw_gpu = {
 
 static void virtio_ccw_gpu_register(void)
 {
-    type_register_static(&virtio_ccw_gpu);
+    if (have_virtio_ccw) {
+        type_register_static(&virtio_ccw_gpu);
+    }
 }
 
 type_init(virtio_ccw_gpu_register)

util/module.c

@@ -304,6 +304,7 @@ static struct {
     { "virtio-gpu-pci-base",   "hw-", "display-virtio-gpu-pci" },
     { "virtio-gpu-pci",        "hw-", "display-virtio-gpu-pci" },
     { "vhost-user-gpu-pci",    "hw-", "display-virtio-gpu-pci" },
+    { "virtio-gpu-ccw",        "hw-", "s390x-virtio-gpu-ccw"   },
     { "virtio-vga-base",       "hw-", "display-virtio-vga"    },
     { "virtio-vga",            "hw-", "display-virtio-vga"    },
     { "vhost-user-vga",        "hw-", "display-virtio-vga"    },