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>

hw/vfio/display.c

@@ -124,6 +124,9 @@ static void vfio_display_dmabuf_update(void *opaque)
 
     primary = vfio_display_get_dmabuf(vdev, DRM_PLANE_TYPE_PRIMARY);
     if (primary == NULL) {
+        if (dpy->ramfb) {
+            ramfb_display_update(dpy->con, dpy->ramfb);
+        }
         return;
     }
 
@@ -181,6 +184,9 @@ static int vfio_display_dmabuf_init(VFIOPCIDevice *vdev, Error **errp)
     vdev->dpy->con = graphic_console_init(DEVICE(vdev), 0,
                                           &vfio_display_dmabuf_ops,
                                           vdev);
+    if (vdev->enable_ramfb) {
+        vdev->dpy->ramfb = ramfb_setup(errp);
+    }
     return 0;
 }
 
@@ -228,6 +234,9 @@ static void vfio_display_region_update(void *opaque)
         return;
     }
     if (!plane.drm_format || !plane.size) {
+        if (dpy->ramfb) {
+            ramfb_display_update(dpy->con, dpy->ramfb);
+        }
         return;
     }
     format = qemu_drm_format_to_pixman(plane.drm_format);
@@ -300,6 +309,9 @@ static int vfio_display_region_init(VFIOPCIDevice *vdev, Error **errp)
     vdev->dpy->con = graphic_console_init(DEVICE(vdev), 0,
                                           &vfio_display_region_ops,
                                           vdev);
+    if (vdev->enable_ramfb) {
+        vdev->dpy->ramfb = ramfb_setup(errp);
+    }
     return 0;
 }
 

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)

hw/vfio/pci.h

@@ -165,6 +165,7 @@ typedef struct VFIOPCIDevice {
     bool no_geforce_quirks;
     bool no_kvm_ioeventfd;
     bool no_vfio_ioeventfd;
+    bool enable_ramfb;
     VFIODisplay *dpy;
 } VFIOPCIDevice;
 

include/hw/vfio/vfio-common.h

@@ -26,6 +26,7 @@
 #include "qemu/queue.h"
 #include "qemu/notify.h"
 #include "ui/console.h"
+#include "hw/display/ramfb.h"
 #ifdef CONFIG_LINUX
 #include <linux/vfio.h>
 #endif
@@ -147,6 +148,7 @@ typedef struct VFIODMABuf {
 
 typedef struct VFIODisplay {
     QemuConsole *con;
+    RAMFBState *ramfb;
     struct {
         VFIORegion buffer;
         DisplaySurface *surface;