Kernel/Graphics: Use VirtIO GPU3DDevice constructor indirectly

We shouldn't expose the VirtIO GPU3DDevice constructor as public method,
so instead, let's use the usual pattern of a static construction method
that uses the constructor within the method.

Kernel/Graphics/VirtIOGPU/GPU3DDevice.cpp

@@ -21,12 +21,8 @@ GPU3DDevice::PerContextState::PerContextState(ContextID context_id, OwnPtr<Memor
 {
 }
 
-GPU3DDevice::GPU3DDevice(GraphicsAdapter& graphics_adapter)
-    : CharacterDevice(28, 0)
-    , m_graphics_adapter(graphics_adapter)
+NonnullRefPtr<GPU3DDevice> GPU3DDevice::must_create(GraphicsAdapter& adapter)
 {
-    m_kernel_context_id = m_graphics_adapter.create_context();
-
     // Setup memory transfer region
     auto region_result = MM.allocate_kernel_region(
         NUM_TRANSFER_REGION_PAGES * PAGE_SIZE,
@@ -34,7 +30,16 @@ GPU3DDevice::GPU3DDevice(GraphicsAdapter& graphics_adapter)
         Memory::Region::Access::ReadWrite,
         AllocationStrategy::AllocateNow);
     VERIFY(!region_result.is_error());
-    m_transfer_buffer_region = region_result.release_value();
+    auto device = MUST(DeviceManagement::try_create_device<VirtIOGPU::GPU3DDevice>(adapter, region_result.release_value()));
+    return device;
+}
+
+GPU3DDevice::GPU3DDevice(GraphicsAdapter& graphics_adapter, NonnullOwnPtr<Memory::Region> transfer_buffer_region)
+    : CharacterDevice(28, 0)
+    , m_graphics_adapter(graphics_adapter)
+    , m_transfer_buffer_region(move(transfer_buffer_region))
+{
+    m_kernel_context_id = m_graphics_adapter.create_context();
 }
 
 void GPU3DDevice::detach(OpenFileDescription& description)

Kernel/Graphics/VirtIOGPU/GPU3DDevice.h

@@ -8,6 +8,7 @@
 
 #include <AK/DistinctNumeric.h>
 #include <Kernel/Devices/CharacterDevice.h>
+#include <Kernel/Devices/DeviceManagement.h>
 #include <Kernel/Graphics/VirtIOGPU/FramebufferDevice.h>
 #include <Kernel/Graphics/VirtIOGPU/Protocol.h>
 
@@ -87,9 +88,13 @@ union ClearType {
 };
 
 class GPU3DDevice : public CharacterDevice {
+    friend class Kernel::DeviceManagement;
+
 public:
-    GPU3DDevice() = delete;
-    explicit GPU3DDevice(GraphicsAdapter& graphics_adapter);
+    static NonnullRefPtr<GPU3DDevice> must_create(GraphicsAdapter&);
+
+private:
+    GPU3DDevice(GraphicsAdapter& graphics_adapter, NonnullOwnPtr<Memory::Region> transfer_buffer_region);
 
     class PerContextState : public RefCounted<PerContextState> {
     public:
@@ -129,7 +134,7 @@ private:
     ContextID m_kernel_context_id;
     HashMap<OpenFileDescription*, RefPtr<PerContextState>> m_context_state_lookup;
     // Memory management for backing buffers
-    OwnPtr<Memory::Region> m_transfer_buffer_region;
+    NonnullOwnPtr<Memory::Region> m_transfer_buffer_region;
     constexpr static size_t NUM_TRANSFER_REGION_PAGES = 256;
 };
 

Kernel/Graphics/VirtIOGPU/GraphicsAdapter.cpp

@@ -465,7 +465,7 @@ void GraphicsAdapter::initialize_3d_device()
 {
     if (m_has_virgl_support) {
         MutexLocker locker(m_operation_lock);
-        m_3d_device = MUST(DeviceManagement::try_create_device<VirtIOGPU::GPU3DDevice>(*this));
+        m_3d_device = VirtIOGPU::GPU3DDevice::must_create(*this);
     }
 }