Kernel: Enable additional VirtIO displays only on first resolution set

Also, only allocate the amount of memory we actually need for the given
resolution.

Kernel/Graphics/VirtIOGPU/VirtIOFrameBufferDevice.cpp

@@ -14,17 +14,42 @@ VirtIOFrameBufferDevice::VirtIOFrameBufferDevice(VirtIOGPU& virtio_gpu, VirtIOGP
     : BlockDevice(29, GraphicsManagement::the().allocate_minor_device_number())
     , m_gpu(virtio_gpu)
     , m_scanout(scanout)
+{
+    if (display_info().enabled) {
+        Locker locker(m_gpu.operation_lock());
+        create_framebuffer();
+    }
+}
+
+VirtIOFrameBufferDevice::~VirtIOFrameBufferDevice()
+{
+}
+
+void VirtIOFrameBufferDevice::create_framebuffer()
 {
     auto& info = display_info();
 
-    Locker locker(m_gpu.operation_lock());
+    size_t buffer_length = page_round_up(calculate_framebuffer_size(info.rect.width, info.rect.height));
+
+    // First delete any existing framebuffers to free the memory first
+    m_framebuffer = nullptr;
+    m_framebuffer_sink_vmobject = nullptr;
 
     // 1. Allocate frame buffer
-    // FIXME: We really should be trying to allocate a small amount of pages initially, with ensure_backing_storage increasing the backing memory of the region as needed
+    m_framebuffer = MM.allocate_kernel_region(buffer_length, String::formatted("VirtGPU FrameBuffer #{}", m_scanout.value()), Region::Access::Read | Region::Access::Write, AllocationStrategy::AllocateNow);
-    size_t buffer_length = calculate_framebuffer_size(MAX_VIRTIOGPU_RESOLUTION_WIDTH, MAX_VIRTIOGPU_RESOLUTION_HEIGHT);
+    auto write_sink_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No).release_nonnull();
-    m_framebuffer = MM.allocate_kernel_region(page_round_up(buffer_length), String::formatted("VirtGPU FrameBuffer #{}", scanout.value()), Region::Access::Read | Region::Access::Write, AllocationStrategy::AllocateNow);
+    auto num_needed_pages = m_framebuffer->vmobject().page_count();
+    NonnullRefPtrVector<PhysicalPage> pages;
+    for (auto i = 0u; i < num_needed_pages; ++i) {
+        pages.append(write_sink_page);
+    }
+    m_framebuffer_sink_vmobject = AnonymousVMObject::create_with_physical_pages(move(pages));
+
     // 2. Create BUFFER using VIRTIO_GPU_CMD_RESOURCE_CREATE_2D
+    if (m_resource_id.value() != 0)
+        m_gpu.delete_resource(m_resource_id);
     m_resource_id = m_gpu.create_2d_resource(info.rect);
+
     // 3. Attach backing storage using  VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING
     m_gpu.ensure_backing_storage(*m_framebuffer, buffer_length, m_resource_id);
     // 4. Use VIRTIO_GPU_CMD_SET_SCANOUT to link the framebuffer to a display scanout.
@@ -36,17 +61,7 @@ VirtIOFrameBufferDevice::VirtIOFrameBufferDevice(VirtIOGPU& virtio_gpu, VirtIOGP
     // 7. Use VIRTIO_GPU_CMD_RESOURCE_FLUSH to flush the updated resource to the display.
     flush_displayed_image(info.rect);
 
-    auto write_sink_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No).release_nonnull();
+    info.enabled = 1;
-    auto num_needed_pages = m_framebuffer->vmobject().page_count();
-    NonnullRefPtrVector<PhysicalPage> pages;
-    for (auto i = 0u; i < num_needed_pages; ++i) {
-        pages.append(write_sink_page);
-    }
-    m_framebuffer_sink_vmobject = AnonymousVMObject::create_with_physical_pages(move(pages));
-}
-
-VirtIOFrameBufferDevice::~VirtIOFrameBufferDevice()
-{
 }
 
 VirtIOGPURespDisplayInfo::VirtIOGPUDisplayOne const& VirtIOFrameBufferDevice::display_info() const
@@ -84,21 +99,18 @@ bool VirtIOFrameBufferDevice::try_to_set_resolution(size_t width, size_t height)
 {
     if (width > MAX_VIRTIOGPU_RESOLUTION_WIDTH || height > MAX_VIRTIOGPU_RESOLUTION_HEIGHT)
         return false;
+
+    auto& info = display_info();
+
     Locker locker(m_gpu.operation_lock());
-    VirtIOGPURect rect = {
+
+    info.rect = {
         .x = 0,
         .y = 0,
         .width = (u32)width,
         .height = (u32)height,
     };
-    auto old_resource_id = m_resource_id;
+    create_framebuffer();
-    auto new_resource_id = m_gpu.create_2d_resource(rect);
-    m_gpu.ensure_backing_storage(*m_framebuffer, calculate_framebuffer_size(width, height), new_resource_id);
-    m_gpu.set_scanout_resource(m_scanout.value(), new_resource_id, rect);
-    m_gpu.detach_backing_storage(old_resource_id);
-    m_gpu.delete_resource(old_resource_id);
-    m_resource_id = new_resource_id;
-    display_info().rect = rect;
     return true;
 }
 
@@ -278,4 +290,9 @@ void VirtIOFrameBufferDevice::draw_ntsc_test_pattern()
     dbgln_if(VIRTIO_DEBUG, "Finish drawing the pattern");
 }
 
+u8* VirtIOFrameBufferDevice::framebuffer_data()
+{
+    return m_framebuffer->vaddr().as_ptr();
+}
+
 }

Kernel/Graphics/VirtIOGPU/VirtIOFrameBufferDevice.h

@@ -24,9 +24,6 @@ public:
     bool try_to_set_resolution(size_t width, size_t height);
     void clear_to_black();
 
-    VMObject& vm_object() { return m_framebuffer->vmobject(); }
-    Region& region() { return *m_framebuffer; }
-
     size_t width() const { return display_info().rect.width; }
     size_t height() const { return display_info().rect.height; }
     size_t pitch() const { return display_info().rect.width * 4; }
@@ -43,12 +40,16 @@ public:
 
     void draw_ntsc_test_pattern();
 
+    u8* framebuffer_data();
+
 private:
     virtual const char* class_name() const override { return "VirtIOFrameBuffer"; }
 
     VirtIOGPURespDisplayInfo::VirtIOGPUDisplayOne const& display_info() const;
     VirtIOGPURespDisplayInfo::VirtIOGPUDisplayOne& display_info();
 
+    void create_framebuffer();
+
     virtual int ioctl(FileDescription&, unsigned request, FlatPtr arg) override;
     virtual KResultOr<Region*> mmap(Process&, FileDescription&, const Range&, u64 offset, int prot, bool shared) override;
     virtual bool can_read(const FileDescription&, size_t) const override { return true; }

Kernel/Graphics/VirtIOGPU/VirtIOGPU.cpp

@@ -100,14 +100,8 @@ void VirtIOGPU::query_display_information()
         auto& scanout = m_scanouts[i].display_info;
         scanout = response.scanout_modes[i];
         dbgln_if(VIRTIO_DEBUG, "Scanout {}: enabled: {} x: {}, y: {}, width: {}, height: {}", i, !!scanout.enabled, scanout.rect.x, scanout.rect.y, scanout.rect.width, scanout.rect.height);
-        if (scanout.enabled && !m_default_scanout.has_value()) {
+        if (scanout.enabled && !m_default_scanout.has_value())
             m_default_scanout = i;
-        } else if (i < m_num_scanouts) {
-            // TODO: We should not enable all displays until the first resolution set
-            scanout.rect.width = 1024;
-            scanout.rect.height = 768;
-            scanout.enabled = true;
-        }
     }
     VERIFY(m_default_scanout.has_value());
 }

Kernel/Graphics/VirtIOGPU/VirtIOGPUConsole.cpp

@@ -39,7 +39,6 @@ VirtIOGPUConsole::VirtIOGPUConsole(RefPtr<VirtIOFrameBufferDevice> const& frameb
     : GenericFramebufferConsole(framebuffer_device->width(), framebuffer_device->height(), framebuffer_device->pitch())
     , m_framebuffer_device(framebuffer_device)
 {
-    m_framebuffer_region = m_framebuffer_device->region();
     enqueue_refresh_timer();
 }
 
@@ -85,4 +84,9 @@ void VirtIOGPUConsole::enable()
     m_dirty_rect.union_rect(0, 0, m_width, m_height);
 }
 
+u8* VirtIOGPUConsole::framebuffer_data()
+{
+    return m_framebuffer_device->framebuffer_data();
+}
+
 }

Kernel/Graphics/VirtIOGPU/VirtIOGPUConsole.h

@@ -40,13 +40,9 @@ public:
 
 private:
     void enqueue_refresh_timer();
-    virtual u8* framebuffer_data() override
+    virtual u8* framebuffer_data() override;
-    {
-        return m_framebuffer_region.unsafe_ptr()->vaddr().as_ptr();
-    }
 
     VirtIOGPUConsole(RefPtr<VirtIOFrameBufferDevice> const&);
-    WeakPtr<Region> m_framebuffer_region;
     RefPtr<VirtIOFrameBufferDevice> m_framebuffer_device;
     DirtyRect m_dirty_rect;
 };