[RFC] hw/display: add virtio-ramfb device

[Joelle van Dyne <j@getutm.app>]

Like virtio-vga, but using ramfb instead of legacy vga.
Useful for booting from OVMF (with updated drivers) into Windows
ARM which expects a linear FB that the virtio-gpu driver in OVMF
does not provide.

This code was originally written by Gerd Hoffmann and was
updated to contain later changes to the display driver tree.

Co-authored-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Joelle van Dyne <j@getutm.app>
---
 hw/display/virtio-ramfb.c | 188 ++++++++++++++++++++++++++++++++++++++
 hw/display/meson.build    |   1 +
 2 files changed, 189 insertions(+)
 create mode 100644 hw/display/virtio-ramfb.c

diff --git a/hw/display/virtio-ramfb.c b/hw/display/virtio-ramfb.c
new file mode 100644
index 0000000000..d08bb90a14
--- /dev/null
+++ b/hw/display/virtio-ramfb.c
@@ -0,0 +1,188 @@
+#include "qemu/osdep.h"
+#include "hw/pci/pci.h"
+#include "ui/console.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/virtio-gpu-pci.h"
+#include "qapi/error.h"
+#include "hw/display/ramfb.h"
+#include "qom/object.h"
+
+/*
+ * virtio-ramfb-base: This extends VirtioPCIProxy.
+ */
+#define TYPE_VIRTIO_RAMFB_BASE "virtio-ramfb-base"
+OBJECT_DECLARE_TYPE(VirtIORAMFBBase, VirtIORAMFBBaseClass,
+                    VIRTIO_RAMFB_BASE)
+
+struct VirtIORAMFBBase {
+    VirtIOPCIProxy parent_obj;
+
+    VirtIOGPUBase *vgpu;
+    RAMFBState    *ramfb;
+};
+
+struct VirtIORAMFBBaseClass {
+    VirtioPCIClass parent_class;
+
+    DeviceReset parent_reset;
+};
+
+static void virtio_ramfb_invalidate_display(void *opaque)
+{
+    VirtIORAMFBBase *vramfb = opaque;
+    VirtIOGPUBase *g = vramfb->vgpu;
+
+    if (g->enable) {
+        g->hw_ops->invalidate(g);
+    }
+}
+
+static void virtio_ramfb_update_display(void *opaque)
+{
+    VirtIORAMFBBase *vramfb = opaque;
+    VirtIOGPUBase *g = vramfb->vgpu;
+
+    if (g->enable) {
+        g->hw_ops->gfx_update(g);
+    } else {
+        ramfb_display_update(g->scanout[0].con, vramfb->ramfb);
+    }
+}
+
+static int virtio_ramfb_ui_info(void *opaque, uint32_t idx, QemuUIInfo *info)
+{
+    VirtIORAMFBBase *vramfb = opaque;
+    VirtIOGPUBase *g = vramfb->vgpu;
+
+    if (g->hw_ops->ui_info) {
+        return g->hw_ops->ui_info(g, idx, info);
+    }
+    return -1;
+}
+
+static void virtio_ramfb_gl_block(void *opaque, bool block)
+{
+    VirtIORAMFBBase *vramfb = opaque;
+    VirtIOGPUBase *g = vramfb->vgpu;
+
+    if (g->hw_ops->gl_block) {
+        g->hw_ops->gl_block(g, block);
+    }
+}
+
+static const GraphicHwOps virtio_ramfb_ops = {
+    .invalidate = virtio_ramfb_invalidate_display,
+    .gfx_update = virtio_ramfb_update_display,
+    .ui_info = virtio_ramfb_ui_info,
+    .gl_block = virtio_ramfb_gl_block,
+};
+
+static const VMStateDescription vmstate_virtio_ramfb = {
+    .name = "virtio-ramfb",
+    .version_id = 2,
+    .minimum_version_id = 2,
+    .fields = (VMStateField[]) {
+        /* no pci stuff here, saving the virtio device will handle that */
+        /* FIXME */
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+/* RAMFB device wrapper around PCI device around virtio GPU */
+static void virtio_ramfb_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
+{
+    VirtIORAMFBBase *vramfb = VIRTIO_RAMFB_BASE(vpci_dev);
+    VirtIOGPUBase *g = vramfb->vgpu;
+    int i;
+
+    /* init virtio bits */
+    virtio_pci_force_virtio_1(vpci_dev);
+    if (!qdev_realize(DEVICE(g), BUS(&vpci_dev->bus), errp)) {
+        return;
+    }
+
+    /* init ramfb */
+    vramfb->ramfb = ramfb_setup(errp);
+    graphic_console_set_hwops(g->scanout[0].con, &virtio_ramfb_ops, vramfb);
+
+    for (i = 0; i < g->conf.max_outputs; i++) {
+        object_property_set_link(OBJECT(g->scanout[i].con), "device",
+                                 OBJECT(vpci_dev), &error_abort);
+    }
+}
+
+static void virtio_ramfb_reset(DeviceState *dev)
+{
+    VirtIORAMFBBaseClass *klass = VIRTIO_RAMFB_BASE_GET_CLASS(dev);
+
+    /* reset virtio-gpu */
+    klass->parent_reset(dev);
+}
+
+static Property virtio_ramfb_base_properties[] = {
+    DEFINE_VIRTIO_GPU_PCI_PROPERTIES(VirtIOPCIProxy),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void virtio_ramfb_base_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
+    VirtIORAMFBBaseClass *v = VIRTIO_RAMFB_BASE_CLASS(klass);
+    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
+
+    set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
+    device_class_set_props(dc, virtio_ramfb_base_properties);
+    dc->vmsd = &vmstate_virtio_ramfb;
+    dc->hotpluggable = false;
+    device_class_set_parent_reset(dc, virtio_ramfb_reset,
+                                  &v->parent_reset);
+
+    k->realize = virtio_ramfb_realize;
+    pcidev_k->class_id = PCI_CLASS_DISPLAY_OTHER;
+}
+
+static TypeInfo virtio_ramfb_base_info = {
+    .name          = TYPE_VIRTIO_RAMFB_BASE,
+    .parent        = TYPE_VIRTIO_PCI,
+    .instance_size = sizeof(VirtIORAMFBBase),
+    .class_size    = sizeof(VirtIORAMFBBaseClass),
+    .class_init    = virtio_ramfb_base_class_init,
+    .abstract      = true,
+};
+
+#define TYPE_VIRTIO_RAMFB "virtio-ramfb"
+
+typedef struct VirtIORAMFB VirtIORAMFB;
+DECLARE_INSTANCE_CHECKER(VirtIORAMFB, VIRTIO_RAMFB,
+                         TYPE_VIRTIO_RAMFB)
+
+struct VirtIORAMFB {
+    VirtIORAMFBBase parent_obj;
+
+    VirtIOGPU     vdev;
+};
+
+static void virtio_ramfb_inst_initfn(Object *obj)
+{
+    VirtIORAMFB *dev = VIRTIO_RAMFB(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VIRTIO_GPU);
+    VIRTIO_RAMFB_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
+}
+
+static VirtioPCIDeviceTypeInfo virtio_ramfb_info = {
+    .generic_name  = TYPE_VIRTIO_RAMFB,
+    .parent        = TYPE_VIRTIO_RAMFB_BASE,
+    .instance_size = sizeof(VirtIORAMFB),
+    .instance_init = virtio_ramfb_inst_initfn,
+};
+
+static void virtio_ramfb_register_types(void)
+{
+    type_register_static(&virtio_ramfb_base_info);
+    virtio_pci_types_register(&virtio_ramfb_info);
+}
+
+type_init(virtio_ramfb_register_types)
diff --git a/hw/display/meson.build b/hw/display/meson.build
index 9d79e3951d..14f5fa39f4 100644
--- a/hw/display/meson.build
+++ b/hw/display/meson.build
@@ -60,6 +60,7 @@ if config_all_devices.has_key('CONFIG_VIRTIO_GPU')
   virtio_gpu_ss.add(when: ['CONFIG_VIRTIO_GPU', 'CONFIG_VIRGL'],
                     if_true: [files('virtio-gpu-3d.c'), pixman, virgl])
   virtio_gpu_ss.add(when: 'CONFIG_VHOST_USER_GPU', if_true: files('vhost-user-gpu.c'))
+  virtio_gpu_ss.add(when: 'CONFIG_FW_CFG_DMA', if_true: files('virtio-ramfb.c'))
   hw_display_modules += {'virtio-gpu': virtio_gpu_ss}
 endif
 
-- 
2.28.0