hw/vfio/display: add ramfb support

So we have a boot display when using a vgpu as primary display.

ramfb depends on a fw_cfg file.  fw_cfg files can not be added and
removed at runtime, therefore a ramfb-enabled vfio device can't be
hotplugged.

Add a nohotplug variant of the vfio-pci device (as child class).  Add
the ramfb property to the nohotplug variant only.  So to enable the vgpu
display with boot support use this:

  -device vfio-pci-nohotplug,display=on,ramfb=on,sysfsdev=...

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 866f0deeb7..a0047f4942 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3067,6 +3067,10 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
             goto out_teardown;
         }
     }
+    if (vdev->enable_ramfb && vdev->dpy == NULL) {
+        error_setg(errp, "ramfb=on requires display=on");
+        goto out_teardown;
+    }
 
     vfio_register_err_notifier(vdev);
     vfio_register_req_notifier(vdev);
@@ -3258,9 +3262,30 @@ static const TypeInfo vfio_pci_dev_info = {
     },
 };
 
+static Property vfio_pci_dev_nohotplug_properties[] = {
+    DEFINE_PROP_BOOL("ramfb", VFIOPCIDevice, enable_ramfb, false),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vfio_pci_nohotplug_dev_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = vfio_pci_dev_nohotplug_properties;
+    dc->hotpluggable = false;
+}
+
+static const TypeInfo vfio_pci_nohotplug_dev_info = {
+    .name = "vfio-pci-nohotplug",
+    .parent = "vfio-pci",
+    .instance_size = sizeof(VFIOPCIDevice),
+    .class_init = vfio_pci_nohotplug_dev_class_init,
+};
+
 static void register_vfio_pci_dev_type(void)
 {
     type_register_static(&vfio_pci_dev_info);
+    type_register_static(&vfio_pci_nohotplug_dev_info);
 }
 
 type_init(register_vfio_pci_dev_type)