diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
index 317d333..526e7da 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/DisplayCreationArgs.h
@@ -21,13 +21,10 @@
 #include <string>
 
 #include <ui/DisplayId.h>
-#include <ui/PixelFormat.h>
 #include <ui/Size.h>
 #include <ui/StaticDisplayInfo.h>
 
-#include "DisplayHardware/DisplayIdentification.h"
 #include "DisplayHardware/PowerAdvisor.h"
-#include "DisplayIdGenerator.h"
 
 namespace android::compositionengine {
 
@@ -37,24 +34,14 @@
  * A parameter object for creating Display instances
  */
 struct DisplayCreationArgs {
-    struct Physical {
-        DisplayId id;
-        ui::DisplayConnectionType type;
-    };
+    DisplayId id;
 
-    // Required for physical displays. Gives the HWC display id for the existing
-    // display along with the connection type.
-    std::optional<Physical> physical;
+    // Unset for virtual displays
+    std::optional<ui::DisplayConnectionType> connectionType;
 
     // Size of the display in pixels
     ui::Size pixels = ui::kInvalidSize;
 
-    // Pixel format of the display
-    ui::PixelFormat pixelFormat = static_cast<ui::PixelFormat>(PIXEL_FORMAT_UNKNOWN);
-
-    // True if virtual displays should be created with the HWC API if possible
-    bool useHwcVirtualDisplays = false;
-
     // True if this display should be considered secure
     bool isSecure = false;
 
@@ -67,9 +54,6 @@
 
     // Debugging. Human readable name for the display.
     std::string name;
-
-    // Generator for IDs of virtual displays, which are backed by the GPU.
-    DisplayIdGenerator<GpuVirtualDisplayId>* gpuVirtualDisplayIdGenerator;
 };
 
 /**
@@ -80,8 +64,13 @@
 public:
     DisplayCreationArgs build() { return std::move(mArgs); }
 
-    DisplayCreationArgsBuilder& setPhysical(DisplayCreationArgs::Physical physical) {
-        mArgs.physical = physical;
+    DisplayCreationArgsBuilder& setId(DisplayId id) {
+        mArgs.id = id;
+        return *this;
+    }
+
+    DisplayCreationArgsBuilder& setConnectionType(ui::DisplayConnectionType connectionType) {
+        mArgs.connectionType = connectionType;
         return *this;
     }
 
@@ -90,22 +79,6 @@
         return *this;
     }
 
-    DisplayCreationArgsBuilder& setPixelFormat(ui::PixelFormat pixelFormat) {
-        mArgs.pixelFormat = pixelFormat;
-        return *this;
-    }
-
-    DisplayCreationArgsBuilder& setUseHwcVirtualDisplays(bool useHwcVirtualDisplays) {
-        mArgs.useHwcVirtualDisplays = useHwcVirtualDisplays;
-        return *this;
-    }
-
-    DisplayCreationArgsBuilder& setGpuVirtualDisplayIdGenerator(
-            DisplayIdGenerator<GpuVirtualDisplayId>& generator) {
-        mArgs.gpuVirtualDisplayIdGenerator = &generator;
-        return *this;
-    }
-
     DisplayCreationArgsBuilder& setIsSecure(bool isSecure) {
         mArgs.isSecure = isSecure;
         return *this;
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
index 54e91ae..bb540ea 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Display.h
@@ -80,19 +80,13 @@
 
     // Internal
     virtual void setConfiguration(const compositionengine::DisplayCreationArgs&);
-    virtual std::optional<DisplayId> maybeAllocateDisplayIdForVirtualDisplay(ui::Size,
-                                                                             ui::PixelFormat) const;
     std::unique_ptr<compositionengine::OutputLayer> createOutputLayer(const sp<LayerFE>&) const;
 
-    // Testing
-    void setDisplayIdForTesting(DisplayId displayId);
-
 private:
     bool mIsVirtual = false;
     bool mIsDisconnected = false;
     DisplayId mId;
     Hwc2::PowerAdvisor* mPowerAdvisor = nullptr;
-    DisplayIdGenerator<GpuVirtualDisplayId>* mGpuVirtualDisplayIdGenerator;
 };
 
 // This template factory function standardizes the implementation details of the
diff --git a/services/surfaceflinger/CompositionEngine/src/Display.cpp b/services/surfaceflinger/CompositionEngine/src/Display.cpp
index 1ffb1c8..7d84cb5 100644
--- a/services/surfaceflinger/CompositionEngine/src/Display.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Display.cpp
@@ -50,36 +50,14 @@
 Display::~Display() = default;
 
 void Display::setConfiguration(const compositionengine::DisplayCreationArgs& args) {
-    mIsVirtual = !args.physical;
+    mId = args.id;
+    mIsVirtual = !args.connectionType;
     mPowerAdvisor = args.powerAdvisor;
     editState().isSecure = args.isSecure;
     editState().displaySpace.bounds = Rect(args.pixels);
     setLayerStackFilter(args.layerStackId,
-                        args.physical &&
-                                args.physical->type == ui::DisplayConnectionType::Internal);
+                        args.connectionType == ui::DisplayConnectionType::Internal);
     setName(args.name);
-    mGpuVirtualDisplayIdGenerator = args.gpuVirtualDisplayIdGenerator;
-
-    if (args.physical) {
-        mId = args.physical->id;
-    } else {
-        std::optional<DisplayId> id;
-        if (args.useHwcVirtualDisplays) {
-            id = maybeAllocateDisplayIdForVirtualDisplay(args.pixels, args.pixelFormat);
-        }
-        if (!id) {
-            id = mGpuVirtualDisplayIdGenerator->nextId();
-        }
-        LOG_ALWAYS_FATAL_IF(!id, "Failed to generate display ID");
-        mId = *id;
-    }
-}
-
-std::optional<DisplayId> Display::maybeAllocateDisplayIdForVirtualDisplay(
-        ui::Size pixels, ui::PixelFormat pixelFormat) const {
-    auto& hwc = getCompositionEngine().getHwComposer();
-    return hwc.allocateVirtualDisplay(static_cast<uint32_t>(pixels.width),
-                                      static_cast<uint32_t>(pixels.height), &pixelFormat);
 }
 
 bool Display::isValid() const {
@@ -102,23 +80,16 @@
     return mId;
 }
 
-void Display::setDisplayIdForTesting(DisplayId displayId) {
-    mId = displayId;
-}
-
 void Display::disconnect() {
     if (mIsDisconnected) {
         return;
     }
 
     mIsDisconnected = true;
-    if (const auto id = GpuVirtualDisplayId::tryCast(mId)) {
-        mGpuVirtualDisplayIdGenerator->markUnused(*id);
-        return;
+
+    if (const auto id = HalDisplayId::tryCast(mId)) {
+        getCompositionEngine().getHwComposer().disconnectDisplay(*id);
     }
-    const auto halDisplayId = HalDisplayId::tryCast(mId);
-    LOG_FATAL_IF(!halDisplayId);
-    getCompositionEngine().getHwComposer().disconnectDisplay(*halDisplayId);
 }
 
 void Display::setColorTransform(const compositionengine::CompositionRefreshArgs& args) {
diff --git a/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp b/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
index 492db43..5c9421b 100644
--- a/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/DisplayTest.cpp
@@ -14,10 +14,6 @@
  * limitations under the License.
  */
 
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wextra"
-
 #include <cmath>
 
 #include <compositionengine/DisplayColorProfileCreationArgs.h>
@@ -60,13 +56,12 @@
 using testing::SetArgPointee;
 using testing::StrictMock;
 
-constexpr PhysicalDisplayId DEFAULT_DISPLAY_ID = PhysicalDisplayId::fromPort(42u);
-// TODO(b/160679868) Use VirtualDisplayId
-constexpr PhysicalDisplayId VIRTUAL_DISPLAY_ID = PhysicalDisplayId::fromPort(43u);
+constexpr PhysicalDisplayId DEFAULT_DISPLAY_ID = PhysicalDisplayId::fromPort(123u);
+constexpr HalVirtualDisplayId HAL_VIRTUAL_DISPLAY_ID{456u};
+constexpr GpuVirtualDisplayId GPU_VIRTUAL_DISPLAY_ID{789u};
 
-constexpr int32_t DEFAULT_DISPLAY_WIDTH = 1920;
-constexpr int32_t DEFAULT_DISPLAY_HEIGHT = 1080;
-constexpr int32_t DEFAULT_LAYER_STACK = 123;
+constexpr ui::Size DEFAULT_RESOLUTION{1920, 1080};
+constexpr uint32_t DEFAULT_LAYER_STACK = 42;
 
 struct Layer {
     Layer() {
@@ -95,8 +90,6 @@
     public:
         using impl::Display::injectOutputLayerForTest;
         virtual void injectOutputLayerForTest(std::unique_ptr<compositionengine::OutputLayer>) = 0;
-
-        using impl::Display::maybeAllocateDisplayIdForVirtualDisplay;
     };
 
     // Uses a special implementation with key internal member functions set up
@@ -170,21 +163,19 @@
 
     DisplayCreationArgs getDisplayCreationArgsForPhysicalHWCDisplay() {
         return DisplayCreationArgsBuilder()
-                .setPhysical({DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::Internal})
-                .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
-                .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
+                .setId(DEFAULT_DISPLAY_ID)
+                .setConnectionType(ui::DisplayConnectionType::Internal)
+                .setPixels(DEFAULT_RESOLUTION)
                 .setIsSecure(true)
                 .setLayerStackId(DEFAULT_LAYER_STACK)
                 .setPowerAdvisor(&mPowerAdvisor)
                 .build();
     }
 
-    DisplayCreationArgs getDisplayCreationArgsForNonHWCVirtualDisplay() {
+    DisplayCreationArgs getDisplayCreationArgsForGpuVirtualDisplay() {
         return DisplayCreationArgsBuilder()
-                .setUseHwcVirtualDisplays(false)
-                .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
-                .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
-                .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
+                .setId(GPU_VIRTUAL_DISPLAY_ID)
+                .setPixels(DEFAULT_RESOLUTION)
                 .setIsSecure(false)
                 .setLayerStackId(DEFAULT_LAYER_STACK)
                 .setPowerAdvisor(&mPowerAdvisor)
@@ -196,7 +187,6 @@
     StrictMock<renderengine::mock::RenderEngine> mRenderEngine;
     StrictMock<mock::CompositionEngine> mCompositionEngine;
     sp<mock::NativeWindow> mNativeWindow = new StrictMock<mock::NativeWindow>();
-    RandomDisplayIdGenerator<GpuVirtualDisplayId> mGpuDisplayIdGenerator;
 };
 
 struct PartialMockDisplayTestCommon : public DisplayTestCommon {
@@ -248,9 +238,9 @@
     EXPECT_EQ(DEFAULT_DISPLAY_ID, display->getId());
 }
 
-TEST_F(DisplayCreationTest, createNonHwcVirtualDisplay) {
-    auto display = impl::createDisplay(mCompositionEngine,
-                                       getDisplayCreationArgsForNonHWCVirtualDisplay());
+TEST_F(DisplayCreationTest, createGpuVirtualDisplay) {
+    auto display =
+            impl::createDisplay(mCompositionEngine, getDisplayCreationArgsForGpuVirtualDisplay());
     EXPECT_FALSE(display->isSecure());
     EXPECT_TRUE(display->isVirtual());
     EXPECT_TRUE(GpuVirtualDisplayId::tryCast(display->getId()));
@@ -263,17 +253,15 @@
 using DisplaySetConfigurationTest = PartialMockDisplayTestCommon;
 
 TEST_F(DisplaySetConfigurationTest, configuresInternalSecurePhysicalDisplay) {
-    mDisplay->setConfiguration(
-            DisplayCreationArgsBuilder()
-                    .setUseHwcVirtualDisplays(true)
-                    .setPhysical({DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::Internal})
-                    .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
-                    .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
-                    .setIsSecure(true)
-                    .setLayerStackId(DEFAULT_LAYER_STACK)
-                    .setPowerAdvisor(&mPowerAdvisor)
-                    .setName(getDisplayNameFromCurrentTest())
-                    .build());
+    mDisplay->setConfiguration(DisplayCreationArgsBuilder()
+                                       .setId(DEFAULT_DISPLAY_ID)
+                                       .setConnectionType(ui::DisplayConnectionType::Internal)
+                                       .setPixels(DEFAULT_RESOLUTION)
+                                       .setIsSecure(true)
+                                       .setLayerStackId(DEFAULT_LAYER_STACK)
+                                       .setPowerAdvisor(&mPowerAdvisor)
+                                       .setName(getDisplayNameFromCurrentTest())
+                                       .build());
 
     EXPECT_EQ(DEFAULT_DISPLAY_ID, mDisplay->getId());
     EXPECT_TRUE(mDisplay->isSecure());
@@ -284,17 +272,15 @@
 }
 
 TEST_F(DisplaySetConfigurationTest, configuresExternalInsecurePhysicalDisplay) {
-    mDisplay->setConfiguration(
-            DisplayCreationArgsBuilder()
-                    .setUseHwcVirtualDisplays(true)
-                    .setPhysical({DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::External})
-                    .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
-                    .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
-                    .setIsSecure(false)
-                    .setLayerStackId(DEFAULT_LAYER_STACK)
-                    .setPowerAdvisor(&mPowerAdvisor)
-                    .setName(getDisplayNameFromCurrentTest())
-                    .build());
+    mDisplay->setConfiguration(DisplayCreationArgsBuilder()
+                                       .setId(DEFAULT_DISPLAY_ID)
+                                       .setConnectionType(ui::DisplayConnectionType::External)
+                                       .setPixels(DEFAULT_RESOLUTION)
+                                       .setIsSecure(false)
+                                       .setLayerStackId(DEFAULT_LAYER_STACK)
+                                       .setPowerAdvisor(&mPowerAdvisor)
+                                       .setName(getDisplayNameFromCurrentTest())
+                                       .build());
 
     EXPECT_EQ(DEFAULT_DISPLAY_ID, mDisplay->getId());
     EXPECT_FALSE(mDisplay->isSecure());
@@ -304,25 +290,17 @@
     EXPECT_FALSE(mDisplay->isValid());
 }
 
-TEST_F(DisplaySetConfigurationTest, configuresHwcBackedVirtualDisplay) {
-    EXPECT_CALL(mHwComposer,
-                allocateVirtualDisplay(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH,
-                                       Pointee(Eq(static_cast<ui::PixelFormat>(
-                                               PIXEL_FORMAT_RGBA_8888)))))
-            .WillOnce(Return(VIRTUAL_DISPLAY_ID));
+TEST_F(DisplaySetConfigurationTest, configuresHalVirtualDisplay) {
+    mDisplay->setConfiguration(DisplayCreationArgsBuilder()
+                                       .setId(HAL_VIRTUAL_DISPLAY_ID)
+                                       .setPixels(DEFAULT_RESOLUTION)
+                                       .setIsSecure(false)
+                                       .setLayerStackId(DEFAULT_LAYER_STACK)
+                                       .setPowerAdvisor(&mPowerAdvisor)
+                                       .setName(getDisplayNameFromCurrentTest())
+                                       .build());
 
-    mDisplay->setConfiguration(
-            DisplayCreationArgsBuilder()
-                    .setUseHwcVirtualDisplays(true)
-                    .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
-                    .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
-                    .setIsSecure(false)
-                    .setLayerStackId(DEFAULT_LAYER_STACK)
-                    .setPowerAdvisor(&mPowerAdvisor)
-                    .setName(getDisplayNameFromCurrentTest())
-                    .build());
-
-    EXPECT_EQ(VIRTUAL_DISPLAY_ID, mDisplay->getId());
+    EXPECT_EQ(HAL_VIRTUAL_DISPLAY_ID, mDisplay->getId());
     EXPECT_FALSE(mDisplay->isSecure());
     EXPECT_TRUE(mDisplay->isVirtual());
     EXPECT_EQ(DEFAULT_LAYER_STACK, mDisplay->getState().layerStackId);
@@ -330,47 +308,17 @@
     EXPECT_FALSE(mDisplay->isValid());
 }
 
-TEST_F(DisplaySetConfigurationTest, configuresNonHwcBackedVirtualDisplayIfHwcAllocationFails) {
-    EXPECT_CALL(mHwComposer,
-                allocateVirtualDisplay(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH,
-                                       Pointee(Eq(static_cast<ui::PixelFormat>(
-                                               PIXEL_FORMAT_RGBA_8888)))))
-            .WillOnce(Return(std::nullopt));
+TEST_F(DisplaySetConfigurationTest, configuresGpuVirtualDisplay) {
+    mDisplay->setConfiguration(DisplayCreationArgsBuilder()
+                                       .setId(GPU_VIRTUAL_DISPLAY_ID)
+                                       .setPixels(DEFAULT_RESOLUTION)
+                                       .setIsSecure(false)
+                                       .setLayerStackId(DEFAULT_LAYER_STACK)
+                                       .setPowerAdvisor(&mPowerAdvisor)
+                                       .setName(getDisplayNameFromCurrentTest())
+                                       .build());
 
-    mDisplay->setConfiguration(
-            DisplayCreationArgsBuilder()
-                    .setUseHwcVirtualDisplays(true)
-                    .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
-                    .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
-                    .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
-                    .setIsSecure(false)
-                    .setLayerStackId(DEFAULT_LAYER_STACK)
-                    .setPowerAdvisor(&mPowerAdvisor)
-                    .setName(getDisplayNameFromCurrentTest())
-                    .build());
-
-    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(mDisplay->getId()));
-    EXPECT_FALSE(mDisplay->isSecure());
-    EXPECT_TRUE(mDisplay->isVirtual());
-    EXPECT_EQ(DEFAULT_LAYER_STACK, mDisplay->getState().layerStackId);
-    EXPECT_FALSE(mDisplay->getState().layerStackInternal);
-    EXPECT_FALSE(mDisplay->isValid());
-}
-
-TEST_F(DisplaySetConfigurationTest, configuresNonHwcBackedVirtualDisplayIfShouldNotUseHwc) {
-    mDisplay->setConfiguration(
-            DisplayCreationArgsBuilder()
-                    .setUseHwcVirtualDisplays(false)
-                    .setGpuVirtualDisplayIdGenerator(mGpuDisplayIdGenerator)
-                    .setPixels(ui::Size(DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_WIDTH))
-                    .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
-                    .setIsSecure(false)
-                    .setLayerStackId(DEFAULT_LAYER_STACK)
-                    .setPowerAdvisor(&mPowerAdvisor)
-                    .setName(getDisplayNameFromCurrentTest())
-                    .build());
-
-    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(mDisplay->getId()));
+    EXPECT_EQ(GPU_VIRTUAL_DISPLAY_ID, mDisplay->getId());
     EXPECT_FALSE(mDisplay->isSecure());
     EXPECT_TRUE(mDisplay->isVirtual());
     EXPECT_EQ(DEFAULT_LAYER_STACK, mDisplay->getState().layerStackId);
@@ -477,7 +425,7 @@
 TEST_F(DisplaySetColorModeTest, doesNothingForVirtualDisplay) {
     using ColorProfile = Output::ColorProfile;
 
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
     std::shared_ptr<impl::Display> virtualDisplay = impl::createDisplay(mCompositionEngine, args);
 
     mock::DisplayColorProfile* colorProfile = new StrictMock<mock::DisplayColorProfile>();
@@ -557,25 +505,25 @@
 
 using DisplaySetReleasedLayersTest = DisplayWithLayersTestCommon;
 
-TEST_F(DisplaySetReleasedLayersTest, doesNothingIfNotHwcDisplay) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    std::shared_ptr<impl::Display> nonHwcDisplay = impl::createDisplay(mCompositionEngine, args);
+TEST_F(DisplaySetReleasedLayersTest, doesNothingIfGpuDisplay) {
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    std::shared_ptr<impl::Display> gpuDisplay = impl::createDisplay(mCompositionEngine, args);
 
     sp<mock::LayerFE> layerXLayerFE = new StrictMock<mock::LayerFE>();
 
     {
         Output::ReleasedLayers releasedLayers;
         releasedLayers.emplace_back(layerXLayerFE);
-        nonHwcDisplay->setReleasedLayers(std::move(releasedLayers));
+        gpuDisplay->setReleasedLayers(std::move(releasedLayers));
     }
 
     CompositionRefreshArgs refreshArgs;
     refreshArgs.layersWithQueuedFrames.push_back(layerXLayerFE);
 
-    nonHwcDisplay->setReleasedLayers(refreshArgs);
+    gpuDisplay->setReleasedLayers(refreshArgs);
 
-    const auto& releasedLayers = nonHwcDisplay->getReleasedLayersForTest();
-    ASSERT_EQ(1, releasedLayers.size());
+    const auto& releasedLayers = gpuDisplay->getReleasedLayersForTest();
+    ASSERT_EQ(1u, releasedLayers.size());
 }
 
 TEST_F(DisplaySetReleasedLayersTest, doesNothingIfNoLayersWithQueuedFrames) {
@@ -591,7 +539,7 @@
     mDisplay->setReleasedLayers(refreshArgs);
 
     const auto& releasedLayers = mDisplay->getReleasedLayersForTest();
-    ASSERT_EQ(1, releasedLayers.size());
+    ASSERT_EQ(1u, releasedLayers.size());
 }
 
 TEST_F(DisplaySetReleasedLayersTest, setReleasedLayers) {
@@ -605,7 +553,7 @@
     mDisplay->setReleasedLayers(refreshArgs);
 
     const auto& releasedLayers = mDisplay->getReleasedLayersForTest();
-    ASSERT_EQ(2, releasedLayers.size());
+    ASSERT_EQ(2u, releasedLayers.size());
     ASSERT_EQ(mLayer1.layerFE.get(), releasedLayers[0].promote().get());
     ASSERT_EQ(mLayer2.layerFE.get(), releasedLayers[1].promote().get());
 }
@@ -616,15 +564,15 @@
 
 using DisplayChooseCompositionStrategyTest = PartialMockDisplayTestCommon;
 
-TEST_F(DisplayChooseCompositionStrategyTest, takesEarlyOutIfNotAHwcDisplay) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    std::shared_ptr<Display> nonHwcDisplay =
+TEST_F(DisplayChooseCompositionStrategyTest, takesEarlyOutIfGpuDisplay) {
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    std::shared_ptr<Display> gpuDisplay =
             createPartialMockDisplay<Display>(mCompositionEngine, args);
-    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(nonHwcDisplay->getId()));
+    EXPECT_TRUE(GpuVirtualDisplayId::tryCast(gpuDisplay->getId()));
 
-    nonHwcDisplay->chooseCompositionStrategy();
+    gpuDisplay->chooseCompositionStrategy();
 
-    auto& state = nonHwcDisplay->getState();
+    auto& state = gpuDisplay->getState();
     EXPECT_TRUE(state.usesClientComposition);
     EXPECT_FALSE(state.usesDeviceComposition);
 }
@@ -704,12 +652,12 @@
 
 using DisplayGetSkipColorTransformTest = DisplayWithLayersTestCommon;
 
-TEST_F(DisplayGetSkipColorTransformTest, checksCapabilityIfNonHwcDisplay) {
+TEST_F(DisplayGetSkipColorTransformTest, checksCapabilityIfGpuDisplay) {
     EXPECT_CALL(mHwComposer, hasCapability(hal::Capability::SKIP_CLIENT_COLOR_TRANSFORM))
             .WillOnce(Return(true));
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    auto nonHwcDisplay{impl::createDisplay(mCompositionEngine, args)};
-    EXPECT_TRUE(nonHwcDisplay->getSkipColorTransform());
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    auto gpuDisplay{impl::createDisplay(mCompositionEngine, args)};
+    EXPECT_TRUE(gpuDisplay->getSkipColorTransform());
 }
 
 TEST_F(DisplayGetSkipColorTransformTest, checksDisplayCapability) {
@@ -856,11 +804,11 @@
 
 using DisplayPresentAndGetFrameFencesTest = DisplayWithLayersTestCommon;
 
-TEST_F(DisplayPresentAndGetFrameFencesTest, returnsNoFencesOnNonHwcDisplay) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    auto nonHwcDisplay{impl::createDisplay(mCompositionEngine, args)};
+TEST_F(DisplayPresentAndGetFrameFencesTest, returnsNoFencesOnGpuDisplay) {
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    auto gpuDisplay{impl::createDisplay(mCompositionEngine, args)};
 
-    auto result = nonHwcDisplay->presentAndGetFrameFences();
+    auto result = gpuDisplay->presentAndGetFrameFences();
 
     ASSERT_TRUE(result.presentFence.get());
     EXPECT_FALSE(result.presentFence->isValid());
@@ -888,9 +836,9 @@
     EXPECT_EQ(presentFence, result.presentFence);
 
     EXPECT_EQ(2u, result.layerFences.size());
-    ASSERT_EQ(1, result.layerFences.count(&mLayer1.hwc2Layer));
+    ASSERT_EQ(1u, result.layerFences.count(&mLayer1.hwc2Layer));
     EXPECT_EQ(layer1Fence, result.layerFences[&mLayer1.hwc2Layer]);
-    ASSERT_EQ(1, result.layerFences.count(&mLayer2.hwc2Layer));
+    ASSERT_EQ(1u, result.layerFences.count(&mLayer2.hwc2Layer));
     EXPECT_EQ(layer2Fence, result.layerFences[&mLayer2.hwc2Layer]);
 }
 
@@ -936,66 +884,66 @@
 }
 
 TEST_F(DisplayFinishFrameTest, skipsCompositionIfNotDirty) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    std::shared_ptr<impl::Display> nonHwcDisplay = impl::createDisplay(mCompositionEngine, args);
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    std::shared_ptr<impl::Display> gpuDisplay = impl::createDisplay(mCompositionEngine, args);
 
     mock::RenderSurface* renderSurface = new StrictMock<mock::RenderSurface>();
-    nonHwcDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
+    gpuDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
 
     // We expect no calls to queueBuffer if composition was skipped.
     EXPECT_CALL(*renderSurface, queueBuffer(_)).Times(0);
 
-    nonHwcDisplay->editState().isEnabled = true;
-    nonHwcDisplay->editState().usesClientComposition = false;
-    nonHwcDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
-    nonHwcDisplay->editState().dirtyRegion = Region::INVALID_REGION;
+    gpuDisplay->editState().isEnabled = true;
+    gpuDisplay->editState().usesClientComposition = false;
+    gpuDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
+    gpuDisplay->editState().dirtyRegion = Region::INVALID_REGION;
 
     CompositionRefreshArgs refreshArgs;
     refreshArgs.repaintEverything = false;
 
-    nonHwcDisplay->finishFrame(refreshArgs);
+    gpuDisplay->finishFrame(refreshArgs);
 }
 
 TEST_F(DisplayFinishFrameTest, performsCompositionIfDirty) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    std::shared_ptr<impl::Display> nonHwcDisplay = impl::createDisplay(mCompositionEngine, args);
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    std::shared_ptr<impl::Display> gpuDisplay = impl::createDisplay(mCompositionEngine, args);
 
     mock::RenderSurface* renderSurface = new StrictMock<mock::RenderSurface>();
-    nonHwcDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
+    gpuDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
 
     // We expect a single call to queueBuffer when composition is not skipped.
     EXPECT_CALL(*renderSurface, queueBuffer(_)).Times(1);
 
-    nonHwcDisplay->editState().isEnabled = true;
-    nonHwcDisplay->editState().usesClientComposition = false;
-    nonHwcDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
-    nonHwcDisplay->editState().dirtyRegion = Region(Rect(0, 0, 1, 1));
+    gpuDisplay->editState().isEnabled = true;
+    gpuDisplay->editState().usesClientComposition = false;
+    gpuDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
+    gpuDisplay->editState().dirtyRegion = Region(Rect(0, 0, 1, 1));
 
     CompositionRefreshArgs refreshArgs;
     refreshArgs.repaintEverything = false;
 
-    nonHwcDisplay->finishFrame(refreshArgs);
+    gpuDisplay->finishFrame(refreshArgs);
 }
 
 TEST_F(DisplayFinishFrameTest, performsCompositionIfRepaintEverything) {
-    auto args = getDisplayCreationArgsForNonHWCVirtualDisplay();
-    std::shared_ptr<impl::Display> nonHwcDisplay = impl::createDisplay(mCompositionEngine, args);
+    auto args = getDisplayCreationArgsForGpuVirtualDisplay();
+    std::shared_ptr<impl::Display> gpuDisplay = impl::createDisplay(mCompositionEngine, args);
 
     mock::RenderSurface* renderSurface = new StrictMock<mock::RenderSurface>();
-    nonHwcDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
+    gpuDisplay->setRenderSurfaceForTest(std::unique_ptr<RenderSurface>(renderSurface));
 
     // We expect a single call to queueBuffer when composition is not skipped.
     EXPECT_CALL(*renderSurface, queueBuffer(_)).Times(1);
 
-    nonHwcDisplay->editState().isEnabled = true;
-    nonHwcDisplay->editState().usesClientComposition = false;
-    nonHwcDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
-    nonHwcDisplay->editState().dirtyRegion = Region::INVALID_REGION;
+    gpuDisplay->editState().isEnabled = true;
+    gpuDisplay->editState().usesClientComposition = false;
+    gpuDisplay->editState().layerStackSpace.content = Rect(0, 0, 1, 1);
+    gpuDisplay->editState().dirtyRegion = Region::INVALID_REGION;
 
     CompositionRefreshArgs refreshArgs;
     refreshArgs.repaintEverything = true;
 
-    nonHwcDisplay->finishFrame(refreshArgs);
+    gpuDisplay->finishFrame(refreshArgs);
 }
 
 /*
@@ -1020,23 +968,23 @@
     NiceMock<mock::CompositionEngine> mCompositionEngine;
     sp<mock::NativeWindow> mNativeWindow = new NiceMock<mock::NativeWindow>();
     sp<mock::DisplaySurface> mDisplaySurface = new NiceMock<mock::DisplaySurface>();
+
     std::shared_ptr<Display> mDisplay = impl::createDisplayTemplated<
             Display>(mCompositionEngine,
                      DisplayCreationArgsBuilder()
-                             .setPhysical({DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::Internal})
-                             .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
-                             .setPixelFormat(static_cast<ui::PixelFormat>(PIXEL_FORMAT_RGBA_8888))
+                             .setId(DEFAULT_DISPLAY_ID)
+                             .setConnectionType(ui::DisplayConnectionType::Internal)
+                             .setPixels(DEFAULT_RESOLUTION)
                              .setIsSecure(true)
                              .setLayerStackId(DEFAULT_LAYER_STACK)
                              .setPowerAdvisor(&mPowerAdvisor)
-                             .build()
+                             .build());
 
-    );
     impl::RenderSurface* mRenderSurface =
             new impl::RenderSurface{mCompositionEngine, *mDisplay,
                                     RenderSurfaceCreationArgsBuilder()
-                                            .setDisplayWidth(DEFAULT_DISPLAY_WIDTH)
-                                            .setDisplayHeight(DEFAULT_DISPLAY_HEIGHT)
+                                            .setDisplayWidth(DEFAULT_RESOLUTION.width)
+                                            .setDisplayHeight(DEFAULT_RESOLUTION.height)
                                             .setNativeWindow(mNativeWindow)
                                             .setDisplaySurface(mDisplaySurface)
                                             .build()};
@@ -1055,6 +1003,3 @@
 
 } // namespace
 } // namespace android::compositionengine
-
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic pop // ignored "-Wextra"
diff --git a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
index bac894a..ee4f331 100644
--- a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
+++ b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
@@ -45,9 +45,13 @@
     MOCK_CONST_METHOD1(hasCapability, bool(hal::Capability));
     MOCK_CONST_METHOD2(hasDisplayCapability, bool(HalDisplayId, hal::DisplayCapability));
 
-    MOCK_METHOD3(allocateVirtualDisplay,
-                 std::optional<DisplayId>(uint32_t, uint32_t, ui::PixelFormat*));
+    MOCK_CONST_METHOD0(getMaxVirtualDisplayCount, size_t());
+    MOCK_CONST_METHOD0(getMaxVirtualDisplayDimension, size_t());
+    MOCK_METHOD4(allocateVirtualDisplay,
+                 bool(HalVirtualDisplayId, ui::Size, ui::PixelFormat*,
+                      std::optional<PhysicalDisplayId>));
     MOCK_METHOD2(allocatePhysicalDisplay, void(hal::HWDisplayId, PhysicalDisplayId));
+
     MOCK_METHOD1(createLayer, HWC2::Layer*(HalDisplayId));
     MOCK_METHOD2(destroyLayer, void(HalDisplayId, HWC2::Layer*));
     MOCK_METHOD3(getDeviceCompositionChanges,
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index bf249cd..33c2563 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -103,15 +103,21 @@
     bool needsFiltering() const;
     ui::LayerStack getLayerStack() const;
 
-    // Returns the physical ID of this display. This function asserts the ID is physical and it
-    // shouldn't be called for other display types, e.g. virtual.
+    DisplayId getId() const;
+
+    // Shorthand to upcast the ID of a display whose type is known as a precondition.
     PhysicalDisplayId getPhysicalId() const {
-        const auto displayIdOpt = PhysicalDisplayId::tryCast(getId());
-        LOG_FATAL_IF(!displayIdOpt);
-        return *displayIdOpt;
+        const auto id = PhysicalDisplayId::tryCast(getId());
+        LOG_FATAL_IF(!id);
+        return *id;
     }
 
-    DisplayId getId() const;
+    VirtualDisplayId getVirtualId() const {
+        const auto id = VirtualDisplayId::tryCast(getId());
+        LOG_FATAL_IF(!id);
+        return *id;
+    }
+
     const wp<IBinder>& getDisplayToken() const { return mDisplayToken; }
     int32_t getSequenceId() const { return mSequenceId; }
 
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
index 1cbcf59..caf0294 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
@@ -211,9 +211,8 @@
     return unwrapRet(ret, 0);
 }
 
-Error Composer::createVirtualDisplay(uint32_t width, uint32_t height,
-            PixelFormat* format, Display* outDisplay)
-{
+Error Composer::createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
+                                     std::optional<Display>, Display* outDisplay) {
     const uint32_t bufferSlotCount = 1;
     Error error = kDefaultError;
     if (mClient_2_2) {
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.h b/services/surfaceflinger/DisplayHardware/ComposerHal.h
index 0619b8c..b525e63 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.h
@@ -18,6 +18,7 @@
 #define ANDROID_SF_COMPOSER_HAL_H
 
 #include <memory>
+#include <optional>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -94,8 +95,8 @@
     virtual Error executeCommands() = 0;
 
     virtual uint32_t getMaxVirtualDisplayCount() = 0;
-    virtual Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
-                                       Display* outDisplay) = 0;
+    virtual Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat*,
+                                       std::optional<Display> mirror, Display* outDisplay) = 0;
     virtual Error destroyVirtualDisplay(Display display) = 0;
 
     virtual Error acceptDisplayChanges(Display display) = 0;
@@ -341,7 +342,7 @@
 
     uint32_t getMaxVirtualDisplayCount() override;
     Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
-                               Display* outDisplay) override;
+                               std::optional<Display> mirror, Display* outDisplay) override;
     Error destroyVirtualDisplay(Display display) override;
 
     Error acceptDisplayChanges(Display display) override;
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index b73d032..97cbd07 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -38,7 +38,6 @@
 #include <utils/Trace.h>
 
 #include "../Layer.h" // needed only for debugging
-#include "../SurfaceFlinger.h"
 #include "../SurfaceFlingerProperties.h"
 #include "ComposerHal.h"
 #include "HWC2.h"
@@ -145,8 +144,9 @@
 
 HWComposer::HWComposer(std::unique_ptr<Hwc2::Composer> composer)
       : mComposer(std::move(composer)),
+        mMaxVirtualDisplayDimension(static_cast<size_t>(sysprop::max_virtual_display_dimension(0))),
         mUpdateDeviceProductInfoOnHotplugReconnect(
-                android::sysprop::update_device_product_info_on_hotplug_reconnect(false)) {}
+                sysprop::update_device_product_info_on_hotplug_reconnect(false)) {}
 
 HWComposer::HWComposer(const std::string& composerServiceName)
       : HWComposer(std::make_unique<Hwc2::impl::Composer>(composerServiceName)) {}
@@ -243,38 +243,49 @@
     return true;
 }
 
-std::optional<DisplayId> HWComposer::allocateVirtualDisplay(uint32_t width, uint32_t height,
-                                                            ui::PixelFormat* format) {
-    if (SurfaceFlinger::maxVirtualDisplaySize != 0 &&
-        (width > SurfaceFlinger::maxVirtualDisplaySize ||
-         height > SurfaceFlinger::maxVirtualDisplaySize)) {
-        ALOGE("%s: Display size %ux%u exceeds maximum dimension of %" PRIu64, __FUNCTION__, width,
-              height, SurfaceFlinger::maxVirtualDisplaySize);
-        return {};
+size_t HWComposer::getMaxVirtualDisplayCount() const {
+    return mComposer->getMaxVirtualDisplayCount();
+}
+
+size_t HWComposer::getMaxVirtualDisplayDimension() const {
+    return mMaxVirtualDisplayDimension;
+}
+
+bool HWComposer::allocateVirtualDisplay(HalVirtualDisplayId displayId, ui::Size resolution,
+                                        ui::PixelFormat* format,
+                                        std::optional<PhysicalDisplayId> mirror) {
+    if (!resolution.isValid()) {
+        ALOGE("%s: Invalid resolution %dx%d", __func__, resolution.width, resolution.height);
+        return false;
     }
 
-    const auto displayId = mVirtualIdGenerator.nextId();
-    if (!displayId) {
-        ALOGE("%s: No remaining virtual displays", __FUNCTION__);
-        return {};
+    const uint32_t width = static_cast<uint32_t>(resolution.width);
+    const uint32_t height = static_cast<uint32_t>(resolution.height);
+
+    if (mMaxVirtualDisplayDimension > 0 &&
+        (width > mMaxVirtualDisplayDimension || height > mMaxVirtualDisplayDimension)) {
+        ALOGE("%s: Resolution %ux%u exceeds maximum dimension %zu", __func__, width, height,
+              mMaxVirtualDisplayDimension);
+        return false;
     }
 
-    hal::HWDisplayId hwcDisplayId = 0;
+    std::optional<hal::HWDisplayId> hwcMirrorId;
+    if (mirror) {
+        hwcMirrorId = fromPhysicalDisplayId(*mirror);
+    }
+
+    hal::HWDisplayId hwcDisplayId;
     const auto error = static_cast<hal::Error>(
-            mComposer->createVirtualDisplay(width, height, format, &hwcDisplayId));
-    if (error != hal::Error::NONE) {
-        ALOGE("%s: Failed to create HWC virtual display", __FUNCTION__);
-        mVirtualIdGenerator.markUnused(*displayId);
-        return {};
-    }
+            mComposer->createVirtualDisplay(width, height, format, hwcMirrorId, &hwcDisplayId));
+    RETURN_IF_HWC_ERROR_FOR("createVirtualDisplay", error, displayId, false);
 
     auto display = std::make_unique<HWC2::impl::Display>(*mComposer.get(), mCapabilities,
                                                          hwcDisplayId, hal::DisplayType::VIRTUAL);
     display->setConnected(true);
-    auto& displayData = mDisplayData[*displayId];
+    auto& displayData = mDisplayData[displayId];
     displayData.hwcDisplay = std::move(display);
     displayData.isVirtual = true;
-    return displayId;
+    return true;
 }
 
 void HWComposer::allocatePhysicalDisplay(hal::HWDisplayId hwcDisplayId,
@@ -666,13 +677,6 @@
 void HWComposer::disconnectDisplay(HalDisplayId displayId) {
     RETURN_IF_INVALID_DISPLAY(displayId);
     auto& displayData = mDisplayData[displayId];
-
-    // If this was a virtual display, add its slot back for reuse by future
-    // virtual displays
-    if (displayData.isVirtual) {
-        mVirtualIdGenerator.markUnused(*HalVirtualDisplayId::tryCast(displayId));
-    }
-
     const auto hwcDisplayId = displayData.hwcDisplay->getId();
 
     // TODO(b/74619554): Select internal/external display from remaining displays.
@@ -979,10 +983,6 @@
     }
 }
 
-uint32_t HWComposer::getMaxVirtualDisplayCount() const {
-    return mComposer->getMaxVirtualDisplayCount();
-}
-
 } // namespace impl
 } // namespace android
 
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index f532e50..1f81b8d 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -39,7 +39,6 @@
 #include <utils/StrongPointer.h>
 #include <utils/Timers.h>
 
-#include "DisplayIdGenerator.h"
 #include "DisplayIdentification.h"
 #include "DisplayMode.h"
 #include "HWC2.h"
@@ -109,9 +108,16 @@
     virtual bool hasCapability(hal::Capability) const = 0;
     virtual bool hasDisplayCapability(HalDisplayId, hal::DisplayCapability) const = 0;
 
-    // Attempts to allocate a virtual display and returns its ID if created on the HWC device.
-    virtual std::optional<DisplayId> allocateVirtualDisplay(uint32_t width, uint32_t height,
-                                                            ui::PixelFormat*) = 0;
+    virtual size_t getMaxVirtualDisplayCount() const = 0;
+    virtual size_t getMaxVirtualDisplayDimension() const = 0;
+
+    // Attempts to allocate a virtual display on the HWC. The maximum number of virtual displays
+    // supported by the HWC can be queried in advance, but allocation may fail for other reasons.
+    // For virtualized compositors, the PhysicalDisplayId is a hint that this virtual display is
+    // a mirror of a physical display, and that the screen should be captured by the host rather
+    // than guest compositor.
+    virtual bool allocateVirtualDisplay(HalVirtualDisplayId, ui::Size, ui::PixelFormat*,
+                                        std::optional<PhysicalDisplayId> mirror) = 0;
 
     virtual void allocatePhysicalDisplay(hal::HWDisplayId, PhysicalDisplayId) = 0;
 
@@ -254,9 +260,11 @@
     bool hasCapability(hal::Capability) const override;
     bool hasDisplayCapability(HalDisplayId, hal::DisplayCapability) const override;
 
-    // Attempts to allocate a virtual display and returns its ID if created on the HWC device.
-    std::optional<DisplayId> allocateVirtualDisplay(uint32_t width, uint32_t height,
-                                                    ui::PixelFormat*) override;
+    size_t getMaxVirtualDisplayCount() const override;
+    size_t getMaxVirtualDisplayDimension() const override;
+
+    bool allocateVirtualDisplay(HalVirtualDisplayId, ui::Size, ui::PixelFormat*,
+                                std::optional<PhysicalDisplayId>) override;
 
     // Called from SurfaceFlinger, when the state for a new physical display needs to be recreated.
     void allocatePhysicalDisplay(hal::HWDisplayId, PhysicalDisplayId) override;
@@ -402,7 +410,6 @@
 
     void loadCapabilities();
     void loadLayerMetadataSupport();
-    uint32_t getMaxVirtualDisplayCount() const;
 
     std::unordered_map<HalDisplayId, DisplayData> mDisplayData;
 
@@ -416,8 +423,7 @@
     std::optional<hal::HWDisplayId> mExternalHwcDisplayId;
     bool mHasMultiDisplaySupport = false;
 
-    RandomDisplayIdGenerator<HalVirtualDisplayId> mVirtualIdGenerator{getMaxVirtualDisplayCount()};
-
+    const size_t mMaxVirtualDisplayDimension;
     const bool mUpdateDeviceProductInfoOnHotplugReconnect;
 };
 
diff --git a/services/surfaceflinger/DisplayIdGenerator.h b/services/surfaceflinger/DisplayIdGenerator.h
index e7c69a8..9791a25 100644
--- a/services/surfaceflinger/DisplayIdGenerator.h
+++ b/services/surfaceflinger/DisplayIdGenerator.h
@@ -27,23 +27,16 @@
 
 namespace android {
 
-template <typename T>
+// Generates pseudo-random IDs of type GpuVirtualDisplayId or HalVirtualDisplayId.
+template <typename Id>
 class DisplayIdGenerator {
 public:
-    virtual std::optional<T> nextId() = 0;
-    virtual void markUnused(T id) = 0;
-
-protected:
-    ~DisplayIdGenerator() {}
-};
-
-template <typename T>
-class RandomDisplayIdGenerator final : public DisplayIdGenerator<T> {
-public:
-    explicit RandomDisplayIdGenerator(size_t maxIdsCount = std::numeric_limits<size_t>::max())
+    explicit DisplayIdGenerator(size_t maxIdsCount = std::numeric_limits<size_t>::max())
           : mMaxIdsCount(maxIdsCount) {}
 
-    std::optional<T> nextId() override {
+    bool inUse() const { return !mUsedIds.empty(); }
+
+    std::optional<Id> generateId() {
         if (mUsedIds.size() >= mMaxIdsCount) {
             return std::nullopt;
         }
@@ -51,8 +44,7 @@
         constexpr int kMaxAttempts = 1000;
 
         for (int attempts = 0; attempts < kMaxAttempts; attempts++) {
-            const auto baseId = mDistribution(mGenerator);
-            const T id(baseId);
+            const Id id{mDistribution(mGenerator)};
             if (mUsedIds.count(id) == 0) {
                 mUsedIds.insert(id);
                 return id;
@@ -62,14 +54,18 @@
         LOG_ALWAYS_FATAL("Couldn't generate ID after %d attempts", kMaxAttempts);
     }
 
-    void markUnused(T id) override { mUsedIds.erase(id); }
+    void releaseId(Id id) { mUsedIds.erase(id); }
 
 private:
     const size_t mMaxIdsCount;
 
-    std::unordered_set<T> mUsedIds;
+    std::unordered_set<Id> mUsedIds;
+
+    // Pseudo-random with random seed, in contrast to physical display IDs, which are stable
+    // across reboots. The only ISurfaceComposer exposure for these IDs is a restricted API
+    // for screencap, so there is little benefit in making them unpredictable.
     std::default_random_engine mGenerator{std::random_device()()};
-    std::uniform_int_distribution<typename T::BaseId> mDistribution;
+    std::uniform_int_distribution<typename Id::BaseId> mDistribution;
 };
 
-} // namespace android
\ No newline at end of file
+} // namespace android
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 4b0bdcb..377e685 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -294,7 +294,6 @@
 // ---------------------------------------------------------------------------
 int64_t SurfaceFlinger::dispSyncPresentTimeOffset;
 bool SurfaceFlinger::useHwcForRgbToYuv;
-uint64_t SurfaceFlinger::maxVirtualDisplaySize;
 bool SurfaceFlinger::hasSyncFramework;
 int64_t SurfaceFlinger::maxFrameBufferAcquiredBuffers;
 uint32_t SurfaceFlinger::maxGraphicsWidth;
@@ -356,8 +355,6 @@
 
     useHwcForRgbToYuv = force_hwc_copy_for_virtual_displays(false);
 
-    maxVirtualDisplaySize = max_virtual_display_dimension(0);
-
     maxFrameBufferAcquiredBuffers = max_frame_buffer_acquired_buffers(2);
 
     maxGraphicsWidth = std::max(max_graphics_width(0), 0);
@@ -433,10 +430,6 @@
     ALOGI_IF(mPropagateBackpressureClientComposition,
              "Enabling backpressure propagation for Client Composition");
 
-    property_get("debug.sf.enable_hwc_vds", value, "0");
-    mUseHwcVirtualDisplays = atoi(value);
-    ALOGI_IF(mUseHwcVirtualDisplays, "Enabling HWC virtual displays");
-
     property_get("ro.surface_flinger.supports_background_blur", value, "0");
     bool supportsBlurs = atoi(value);
     mSupportsBlur = supportsBlurs;
@@ -574,6 +567,59 @@
     setTransactionFlags(eDisplayTransactionNeeded);
 }
 
+void SurfaceFlinger::enableHalVirtualDisplays(bool enable) {
+    auto& generator = mVirtualDisplayIdGenerators.hal;
+    if (!generator && enable) {
+        ALOGI("Enabling HAL virtual displays");
+        generator.emplace(getHwComposer().getMaxVirtualDisplayCount());
+    } else if (generator && !enable) {
+        ALOGW_IF(generator->inUse(), "Disabling HAL virtual displays while in use");
+        generator.reset();
+    }
+}
+
+VirtualDisplayId SurfaceFlinger::acquireVirtualDisplay(ui::Size resolution, ui::PixelFormat format,
+                                                       ui::LayerStack layerStack) {
+    if (auto& generator = mVirtualDisplayIdGenerators.hal) {
+        if (const auto id = generator->generateId()) {
+            std::optional<PhysicalDisplayId> mirror;
+
+            if (const auto display = findDisplay([layerStack](const auto& display) {
+                    return !display.isVirtual() && display.getLayerStack() == layerStack;
+                })) {
+                mirror = display->getPhysicalId();
+            }
+
+            if (getHwComposer().allocateVirtualDisplay(*id, resolution, &format, mirror)) {
+                return *id;
+            }
+
+            generator->releaseId(*id);
+        } else {
+            ALOGW("%s: Exhausted HAL virtual displays", __func__);
+        }
+
+        ALOGW("%s: Falling back to GPU virtual display", __func__);
+    }
+
+    const auto id = mVirtualDisplayIdGenerators.gpu.generateId();
+    LOG_ALWAYS_FATAL_IF(!id, "Failed to generate ID for GPU virtual display");
+    return *id;
+}
+
+void SurfaceFlinger::releaseVirtualDisplay(VirtualDisplayId displayId) {
+    if (const auto id = HalVirtualDisplayId::tryCast(displayId)) {
+        if (auto& generator = mVirtualDisplayIdGenerators.hal) {
+            generator->releaseId(*id);
+        }
+        return;
+    }
+
+    const auto id = GpuVirtualDisplayId::tryCast(displayId);
+    LOG_ALWAYS_FATAL_IF(!id);
+    mVirtualDisplayIdGenerators.gpu.releaseId(*id);
+}
+
 std::vector<PhysicalDisplayId> SurfaceFlinger::getPhysicalDisplayIds() const {
     Mutex::Autolock lock(mStateLock);
 
@@ -734,6 +780,11 @@
     mCompositionEngine->setHwComposer(getFactory().createHWComposer(mHwcServiceName));
     mCompositionEngine->getHwComposer().setConfiguration(this, getBE().mComposerSequenceId);
     ClientCache::getInstance().setRenderEngine(&getRenderEngine());
+
+    if (base::GetBoolProperty("debug.sf.enable_hwc_vds"s, false)) {
+        enableHalVirtualDisplays(true);
+    }
+
     // Process any initial hotplug and resulting display changes.
     processDisplayHotplugEventsLocked();
     const auto display = getDefaultDisplayDeviceLocked();
@@ -2625,10 +2676,10 @@
         ALOGE_IF(status != NO_ERROR, "Unable to query width (%d)", status);
         status = state.surface->query(NATIVE_WINDOW_HEIGHT, &resolution.height);
         ALOGE_IF(status != NO_ERROR, "Unable to query height (%d)", status);
-        int intPixelFormat;
-        status = state.surface->query(NATIVE_WINDOW_FORMAT, &intPixelFormat);
+        int format;
+        status = state.surface->query(NATIVE_WINDOW_FORMAT, &format);
         ALOGE_IF(status != NO_ERROR, "Unable to query format (%d)", status);
-        pixelFormat = static_cast<ui::PixelFormat>(intPixelFormat);
+        pixelFormat = static_cast<ui::PixelFormat>(format);
     } else {
         // Virtual displays without a surface are dormant:
         // they have external state (layer stack, projection,
@@ -2638,17 +2689,18 @@
 
     compositionengine::DisplayCreationArgsBuilder builder;
     if (const auto& physical = state.physical) {
-        builder.setPhysical({physical->id, physical->type});
+        builder.setId(physical->id);
+        builder.setConnectionType(physical->type);
+    } else {
+        builder.setId(acquireVirtualDisplay(resolution, pixelFormat, state.layerStack));
     }
+
     builder.setPixels(resolution);
-    builder.setPixelFormat(pixelFormat);
     builder.setIsSecure(state.isSecure);
     builder.setLayerStackId(state.layerStack);
     builder.setPowerAdvisor(&mPowerAdvisor);
-    builder.setUseHwcVirtualDisplays(mUseHwcVirtualDisplays);
-    builder.setGpuVirtualDisplayIdGenerator(mGpuVirtualDisplayIdGenerator);
     builder.setName(state.displayName);
-    const auto compositionDisplay = getCompositionEngine().createDisplay(builder.build());
+    auto compositionDisplay = getCompositionEngine().createDisplay(builder.build());
     compositionDisplay->setLayerCachingEnabled(mLayerCachingEnabled);
 
     sp<compositionengine::DisplaySurface> displaySurface;
@@ -2657,33 +2709,30 @@
     sp<IGraphicBufferConsumer> bqConsumer;
     getFactory().createBufferQueue(&bqProducer, &bqConsumer, /*consumerIsSurfaceFlinger =*/false);
 
-    DisplayId displayId = compositionDisplay->getId();
-
     if (state.isVirtual()) {
-        const auto virtualId = VirtualDisplayId::tryCast(displayId);
-        LOG_FATAL_IF(!virtualId);
-        sp<VirtualDisplaySurface> vds =
-                new VirtualDisplaySurface(getHwComposer(), *virtualId, state.surface, bqProducer,
-                                          bqConsumer, state.displayName);
-
-        displaySurface = vds;
-        producer = vds;
+        const auto displayId = VirtualDisplayId::tryCast(compositionDisplay->getId());
+        LOG_FATAL_IF(!displayId);
+        auto surface = sp<VirtualDisplaySurface>::make(getHwComposer(), *displayId, state.surface,
+                                                       bqProducer, bqConsumer, state.displayName);
+        displaySurface = surface;
+        producer = std::move(surface);
     } else {
         ALOGE_IF(state.surface != nullptr,
                  "adding a supported display, but rendering "
                  "surface is provided (%p), ignoring it",
                  state.surface.get());
-        const auto physicalId = PhysicalDisplayId::tryCast(displayId);
-        LOG_FATAL_IF(!physicalId);
-        displaySurface = new FramebufferSurface(getHwComposer(), *physicalId, bqConsumer,
-                                                state.physical->activeMode->getSize(),
-                                                ui::Size(maxGraphicsWidth, maxGraphicsHeight));
+        const auto displayId = PhysicalDisplayId::tryCast(compositionDisplay->getId());
+        LOG_FATAL_IF(!displayId);
+        displaySurface =
+                sp<FramebufferSurface>::make(getHwComposer(), *displayId, bqConsumer,
+                                             state.physical->activeMode->getSize(),
+                                             ui::Size(maxGraphicsWidth, maxGraphicsHeight));
         producer = bqProducer;
     }
 
     LOG_FATAL_IF(!displaySurface);
-    const auto display = setupNewDisplayDeviceInternal(displayToken, compositionDisplay, state,
-                                                       displaySurface, producer);
+    const auto display = setupNewDisplayDeviceInternal(displayToken, std::move(compositionDisplay),
+                                                       state, displaySurface, producer);
     mDisplays.emplace(displayToken, display);
     if (!state.isVirtual()) {
         dispatchDisplayHotplugEvent(display->getPhysicalId(), true);
@@ -2699,7 +2748,10 @@
     auto display = getDisplayDeviceLocked(displayToken);
     if (display) {
         display->disconnect();
-        if (!display->isVirtual()) {
+
+        if (display->isVirtual()) {
+            releaseVirtualDisplay(display->getVirtualId());
+        } else {
             dispatchDisplayHotplugEvent(display->getPhysicalId(), false);
         }
     }
@@ -2728,17 +2780,26 @@
                                            const DisplayDeviceState& drawingState) {
     const sp<IBinder> currentBinder = IInterface::asBinder(currentState.surface);
     const sp<IBinder> drawingBinder = IInterface::asBinder(drawingState.surface);
+
+    // Recreate the DisplayDevice if the surface or sequence ID changed.
     if (currentBinder != drawingBinder || currentState.sequenceId != drawingState.sequenceId) {
-        // changing the surface is like destroying and recreating the DisplayDevice
         getRenderEngine().cleanFramebufferCache();
+
         if (const auto display = getDisplayDeviceLocked(displayToken)) {
             display->disconnect();
+            if (display->isVirtual()) {
+                releaseVirtualDisplay(display->getVirtualId());
+            }
         }
+
         mDisplays.erase(displayToken);
+
         if (const auto& physical = currentState.physical) {
             getHwComposer().allocatePhysicalDisplay(physical->hwcDisplayId, physical->id);
         }
+
         processDisplayAdded(displayToken, currentState);
+
         if (currentState.physical) {
             const auto display = getDisplayDeviceLocked(displayToken);
             setPowerModeInternal(display, hal::PowerMode::ON);
@@ -4605,7 +4666,8 @@
 
     StringAppendF(&result, " PRESENT_TIME_OFFSET=%" PRId64, dispSyncPresentTimeOffset);
     StringAppendF(&result, " FORCE_HWC_FOR_RBG_TO_YUV=%d", useHwcForRgbToYuv);
-    StringAppendF(&result, " MAX_VIRT_DISPLAY_DIM=%" PRIu64, maxVirtualDisplaySize);
+    StringAppendF(&result, " MAX_VIRT_DISPLAY_DIM=%zu",
+                  getHwComposer().getMaxVirtualDisplayDimension());
     StringAppendF(&result, " RUNNING_WITHOUT_SYNC_FRAMEWORK=%d", !hasSyncFramework);
     StringAppendF(&result, " NUM_FRAMEBUFFER_SURFACE_BUFFERS=%" PRId64,
                   maxFrameBufferAcquiredBuffers);
@@ -5363,8 +5425,8 @@
                 return NO_ERROR;
             }
             case 1021: { // Disable HWC virtual displays
-                n = data.readInt32();
-                mUseHwcVirtualDisplays = !n;
+                const bool enable = data.readInt32() != 0;
+                static_cast<void>(schedule([this, enable] { enableHalVirtualDisplays(enable); }));
                 return NO_ERROR;
             }
             case 1022: { // Set saturation boost
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 4aa047a..b46bd9a 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -228,10 +228,6 @@
     // GL composition.
     static bool useHwcForRgbToYuv;
 
-    // Maximum dimension supported by HWC for virtual display.
-    // Equal to min(max_height, max_width).
-    static uint64_t maxVirtualDisplaySize;
-
     // Controls the number of buffers SurfaceFlinger will allocate for use in
     // FramebufferSurface
     static int64_t maxFrameBufferAcquiredBuffers;
@@ -1084,6 +1080,14 @@
         return hwcDisplayId ? getHwComposer().toPhysicalDisplayId(*hwcDisplayId) : std::nullopt;
     }
 
+    // Toggles use of HAL/GPU virtual displays.
+    void enableHalVirtualDisplays(bool);
+
+    // Virtual display lifecycle for ID generation and HAL allocation.
+    VirtualDisplayId acquireVirtualDisplay(ui::Size, ui::PixelFormat, ui::LayerStack)
+            REQUIRES(mStateLock);
+    void releaseVirtualDisplay(VirtualDisplayId);
+
     /*
      * Debugging & dumpsys
      */
@@ -1236,7 +1240,10 @@
     std::unordered_map<PhysicalDisplayId, sp<IBinder>> mPhysicalDisplayTokens
             GUARDED_BY(mStateLock);
 
-    RandomDisplayIdGenerator<GpuVirtualDisplayId> mGpuVirtualDisplayIdGenerator;
+    struct {
+        DisplayIdGenerator<GpuVirtualDisplayId> gpu;
+        std::optional<DisplayIdGenerator<HalVirtualDisplayId>> hal;
+    } mVirtualDisplayIdGenerators;
 
     std::unordered_map<BBinder*, wp<Layer>> mLayersByLocalBinderToken GUARDED_BY(mStateLock);
 
@@ -1259,7 +1266,7 @@
     const std::shared_ptr<TimeStats> mTimeStats;
     const std::unique_ptr<FrameTracer> mFrameTracer;
     const std::unique_ptr<frametimeline::FrameTimeline> mFrameTimeline;
-    bool mUseHwcVirtualDisplays = false;
+
     // If blurs should be enabled on this device.
     bool mSupportsBlur = false;
     // Disable blurs, for debugging
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index e42cf47..fca3bfc 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -105,7 +105,9 @@
 
         mFlinger.setupRenderEngine(std::unique_ptr<renderengine::RenderEngine>(mRenderEngine));
         mFlinger.setupTimeStats(std::shared_ptr<TimeStats>(mTimeStats));
-        setupComposer(0);
+
+        mComposer = new Hwc2::mock::Composer();
+        mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
     }
 
     ~CompositionTest() {
@@ -114,14 +116,6 @@
         ALOGD("**** Tearing down after %s.%s\n", test_info->test_case_name(), test_info->name());
     }
 
-    void setupComposer(int virtualDisplayCount) {
-        mComposer = new Hwc2::mock::Composer();
-        EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-        mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-        Mock::VerifyAndClear(mComposer);
-    }
-
     void setupScheduler() {
         auto eventThread = std::make_unique<mock::EventThread>();
         auto sfEventThread = std::make_unique<mock::EventThread>();
@@ -289,16 +283,16 @@
         const ::testing::TestInfo* const test_info =
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
-        auto ceDisplayArgs =
-                compositionengine::DisplayCreationArgsBuilder()
-                        .setPhysical({DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::Internal})
-                        .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
-                        .setIsSecure(Derived::IS_SECURE)
-                        .setLayerStackId(DEFAULT_LAYER_STACK)
-                        .setPowerAdvisor(&test->mPowerAdvisor)
-                        .setName(std::string("Injected display for ") +
-                                 test_info->test_case_name() + "." + test_info->name())
-                        .build();
+        auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
+                                     .setId(DEFAULT_DISPLAY_ID)
+                                     .setConnectionType(ui::DisplayConnectionType::Internal)
+                                     .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
+                                     .setIsSecure(Derived::IS_SECURE)
+                                     .setLayerStackId(DEFAULT_LAYER_STACK)
+                                     .setPowerAdvisor(&test->mPowerAdvisor)
+                                     .setName(std::string("Injected display for ") +
+                                              test_info->test_case_name() + "." + test_info->name())
+                                     .build();
 
         auto compositionDisplay =
                 compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
diff --git a/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp b/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp
index 77a3e14..8d4a023 100644
--- a/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayIdGeneratorTest.cpp
@@ -14,76 +14,68 @@
  * limitations under the License.
  */
 
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wextra"
-
 #include <gtest/gtest.h>
+#include <ui/DisplayId.h>
 
+#include <algorithm>
+#include <iterator>
 #include <vector>
 
-#include <ui/DisplayId.h>
 #include "DisplayIdGenerator.h"
 
 namespace android {
 
-template <typename T>
-void testNextId(DisplayIdGenerator<T>& generator) {
-    constexpr int kNumIds = 5;
-    std::vector<T> ids;
-    for (int i = 0; i < kNumIds; i++) {
-        const auto id = generator.nextId();
-        ASSERT_TRUE(id);
-        ids.push_back(*id);
-    }
+template <typename Id>
+void testGenerateId() {
+    DisplayIdGenerator<Id> generator;
+
+    std::vector<std::optional<Id>> ids;
+    std::generate_n(std::back_inserter(ids), 10, [&] { return generator.generateId(); });
 
     // All IDs should be different.
-    for (size_t i = 0; i < kNumIds; i++) {
-        for (size_t j = i + 1; j < kNumIds; j++) {
-            EXPECT_NE(ids[i], ids[j]);
+    for (auto it = ids.begin(); it != ids.end(); ++it) {
+        EXPECT_TRUE(*it);
+
+        for (auto dup = it + 1; dup != ids.end(); ++dup) {
+            EXPECT_NE(*it, *dup);
         }
     }
 }
 
-TEST(DisplayIdGeneratorTest, nextIdGpuVirtual) {
-    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator;
-    testNextId(generator);
+TEST(DisplayIdGeneratorTest, generateGpuVirtualDisplayId) {
+    testGenerateId<GpuVirtualDisplayId>();
 }
 
-TEST(DisplayIdGeneratorTest, nextIdHalVirtual) {
-    RandomDisplayIdGenerator<HalVirtualDisplayId> generator;
-    testNextId(generator);
+TEST(DisplayIdGeneratorTest, generateHalVirtualDisplayId) {
+    testGenerateId<HalVirtualDisplayId>();
 }
 
-TEST(DisplayIdGeneratorTest, markUnused) {
+TEST(DisplayIdGeneratorTest, releaseId) {
     constexpr size_t kMaxIdsCount = 5;
-    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
+    DisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
 
-    const auto id = generator.nextId();
+    const auto id = generator.generateId();
     EXPECT_TRUE(id);
 
-    for (int i = 1; i < kMaxIdsCount; i++) {
-        EXPECT_TRUE(generator.nextId());
+    for (size_t i = 1; i < kMaxIdsCount; i++) {
+        EXPECT_TRUE(generator.generateId());
     }
 
-    EXPECT_FALSE(generator.nextId());
+    EXPECT_FALSE(generator.generateId());
 
-    generator.markUnused(*id);
-    EXPECT_TRUE(generator.nextId());
+    generator.releaseId(*id);
+    EXPECT_TRUE(generator.generateId());
 }
 
 TEST(DisplayIdGeneratorTest, maxIdsCount) {
     constexpr size_t kMaxIdsCount = 5;
-    RandomDisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
+    DisplayIdGenerator<GpuVirtualDisplayId> generator(kMaxIdsCount);
 
-    for (int i = 0; i < kMaxIdsCount; i++) {
-        EXPECT_TRUE(generator.nextId());
+    for (size_t i = 0; i < kMaxIdsCount; i++) {
+        EXPECT_TRUE(generator.generateId());
     }
 
-    EXPECT_FALSE(generator.nextId());
+    EXPECT_FALSE(generator.generateId());
 }
 
 } // namespace android
-
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic pop // ignored "-Wextra"
\ No newline at end of file
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 359e555..60b0f53 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -41,9 +41,6 @@
     mFlinger.mutableUseColorManagement() = false;
     mFlinger.mutableDisplayColorSetting() = DisplayColorSetting::kUnmanaged;
 
-    // Default to using HWC virtual displays
-    mFlinger.mutableUseHwcVirtualDisplays() = true;
-
     mFlinger.setCreateBufferQueueFunction([](auto, auto, auto) {
         ADD_FAILURE() << "Unexpected request to create a buffer queue.";
     });
@@ -85,10 +82,17 @@
 }
 
 void DisplayTransactionTest::injectMockComposer(int virtualDisplayCount) {
+    if (mComposer) {
+        // If reinjecting, disable first to prevent the enable below from being a no-op.
+        mFlinger.enableHalVirtualDisplays(false);
+    }
+
     mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
     mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
 
+    EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
+    mFlinger.enableHalVirtualDisplays(true);
+
     Mock::VerifyAndClear(mComposer);
 }
 
@@ -135,18 +139,21 @@
     EXPECT_CALL(*mNativeWindow, perform(NATIVE_WINDOW_SET_USAGE64));
     EXPECT_CALL(*mNativeWindow, perform(NATIVE_WINDOW_API_DISCONNECT)).Times(AnyNumber());
 
-    auto compositionDisplay = compositionengine::impl::
-            createDisplay(mFlinger.getCompositionEngine(),
-                          compositionengine::DisplayCreationArgsBuilder()
-                                  .setPhysical(
-                                          {DEFAULT_DISPLAY_ID, ui::DisplayConnectionType::Internal})
-                                  .setPixels({DEFAULT_DISPLAY_WIDTH, DEFAULT_DISPLAY_HEIGHT})
-                                  .setPowerAdvisor(&mPowerAdvisor)
-                                  .build());
+    constexpr auto kConnectionType = ui::DisplayConnectionType::Internal;
+    constexpr bool kIsPrimary = true;
 
-    auto injector = FakeDisplayDeviceInjector(mFlinger, compositionDisplay,
-                                              ui::DisplayConnectionType::Internal,
-                                              DEFAULT_DISPLAY_HWC_DISPLAY_ID, true /* isPrimary */);
+    auto compositionDisplay =
+            compositionengine::impl::createDisplay(mFlinger.getCompositionEngine(),
+                                                   compositionengine::DisplayCreationArgsBuilder()
+                                                           .setId(DEFAULT_DISPLAY_ID)
+                                                           .setConnectionType(kConnectionType)
+                                                           .setPixels({DEFAULT_DISPLAY_WIDTH,
+                                                                       DEFAULT_DISPLAY_HEIGHT})
+                                                           .setPowerAdvisor(&mPowerAdvisor)
+                                                           .build());
+
+    auto injector = FakeDisplayDeviceInjector(mFlinger, compositionDisplay, kConnectionType,
+                                              DEFAULT_DISPLAY_HWC_DISPLAY_ID, kIsPrimary);
 
     injector.setNativeWindow(mNativeWindow);
     if (injectExtra) {
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h b/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
index d68fff6..6ce281d 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTestHelpers.h
@@ -263,40 +263,23 @@
 
     static auto makeFakeExistingDisplayInjector(DisplayTransactionTest* test) {
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder();
-        if (auto displayId = PhysicalDisplayId::tryCast(DISPLAY_ID::get())) {
-            ceDisplayArgs.setPhysical({*displayId, ui::DisplayConnectionType::Internal});
-        } else {
-            // We turn off the use of HwcVirtualDisplays, to prevent Composition Engine
-            // from calling into HWComposer. This way all virtual displays will get
-            // a GpuVirtualDisplayId, even if we are in the HwcVirtualDisplayVariant.
-            // In this case we later override it by calling display.setDisplayIdForTesting().
-            ceDisplayArgs.setUseHwcVirtualDisplays(false);
+        ceDisplayArgs.setId(DISPLAY_ID::get())
+                .setPixels({WIDTH, HEIGHT})
+                .setPowerAdvisor(&test->mPowerAdvisor);
 
-            GpuVirtualDisplayId desiredDisplayId = GpuVirtualDisplayId::tryCast(DISPLAY_ID::get())
-                                                           .value_or(GpuVirtualDisplayId(0));
-
-            ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
-                    .WillByDefault(Return(desiredDisplayId));
-
-            auto& generator = test->mFlinger.gpuVirtualDisplayIdGenerator();
-            ceDisplayArgs.setGpuVirtualDisplayIdGenerator(generator);
+        const auto connectionType = CONNECTION_TYPE::value;
+        if (connectionType) {
+            ceDisplayArgs.setConnectionType(*connectionType);
         }
-        ceDisplayArgs.setPixels({WIDTH, HEIGHT}).setPowerAdvisor(&test->mPowerAdvisor);
 
         auto compositionDisplay =
                 compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
                                                        ceDisplayArgs.build());
 
-        if (HalVirtualDisplayId::tryCast(DISPLAY_ID::get())) {
-            // CompositionEngine has assigned a placeholder GpuVirtualDisplayId and we need to
-            // override it with the correct HalVirtualDisplayId.
-            compositionDisplay->setDisplayIdForTesting(DISPLAY_ID::get());
-        }
-
         auto injector =
                 TestableSurfaceFlinger::FakeDisplayDeviceInjector(test->mFlinger,
                                                                   compositionDisplay,
-                                                                  CONNECTION_TYPE::value,
+                                                                  connectionType,
                                                                   HWC_DISPLAY_ID_OPT::value,
                                                                   static_cast<bool>(PRIMARY));
 
@@ -404,8 +387,8 @@
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
-                                     .setPhysical({DisplayVariant::DISPLAY_ID::get(),
-                                                   PhysicalDisplay::CONNECTION_TYPE})
+                                     .setId(DisplayVariant::DISPLAY_ID::get())
+                                     .setConnectionType(PhysicalDisplay::CONNECTION_TYPE)
                                      .setPixels({DisplayVariant::WIDTH, DisplayVariant::HEIGHT})
                                      .setIsSecure(static_cast<bool>(DisplayVariant::SECURE))
                                      .setPowerAdvisor(&test->mPowerAdvisor)
@@ -558,17 +541,13 @@
         const ::testing::TestInfo* const test_info =
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
-        ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
-                .WillByDefault(Return(Base::DISPLAY_ID::get()));
-
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
+                                     .setId(Base::DISPLAY_ID::get())
                                      .setPixels({Base::WIDTH, Base::HEIGHT})
                                      .setIsSecure(static_cast<bool>(Base::SECURE))
                                      .setPowerAdvisor(&test->mPowerAdvisor)
                                      .setName(std::string("Injected display for ") +
                                               test_info->test_case_name() + "." + test_info->name())
-                                     .setGpuVirtualDisplayIdGenerator(
-                                             test->mFlinger.gpuVirtualDisplayIdGenerator())
                                      .build();
 
         return compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
@@ -610,35 +589,22 @@
         const ::testing::TestInfo* const test_info =
                 ::testing::UnitTest::GetInstance()->current_test_info();
 
-        // In order to prevent compostition engine calling into HWComposer, we
-        // 1. turn off the use of HWC virtual displays,
-        // 2. provide a GpuVirtualDisplayIdGenerator which always returns some fake ID
-        // 3. override the ID by calling setDisplayIdForTesting()
-
-        ON_CALL(test->mFlinger.gpuVirtualDisplayIdGenerator(), nextId())
-                .WillByDefault(Return(GpuVirtualDisplayId(0)));
-
+        const auto displayId = Base::DISPLAY_ID::get();
         auto ceDisplayArgs = compositionengine::DisplayCreationArgsBuilder()
-                                     .setUseHwcVirtualDisplays(false)
+                                     .setId(displayId)
                                      .setPixels({Base::WIDTH, Base::HEIGHT})
                                      .setIsSecure(static_cast<bool>(Base::SECURE))
                                      .setPowerAdvisor(&test->mPowerAdvisor)
                                      .setName(std::string("Injected display for ") +
                                               test_info->test_case_name() + "." + test_info->name())
-                                     .setGpuVirtualDisplayIdGenerator(
-                                             test->mFlinger.gpuVirtualDisplayIdGenerator())
                                      .build();
 
         auto compositionDisplay =
                 compositionengine::impl::createDisplay(test->mFlinger.getCompositionEngine(),
                                                        ceDisplayArgs);
-        compositionDisplay->setDisplayIdForTesting(Base::DISPLAY_ID::get());
 
         // Insert display data so that the HWC thinks it created the virtual display.
-        if (const auto displayId = Base::DISPLAY_ID::get();
-            HalVirtualDisplayId::tryCast(displayId)) {
-            test->mFlinger.mutableHwcDisplayData().try_emplace(displayId);
-        }
+        test->mFlinger.mutableHwcDisplayData().try_emplace(displayId);
 
         return compositionDisplay;
     }
@@ -649,8 +615,8 @@
     }
 
     static void setupHwcVirtualDisplayCreationCallExpectations(DisplayTransactionTest* test) {
-        EXPECT_CALL(*test->mComposer, createVirtualDisplay(Base::WIDTH, Base::HEIGHT, _, _))
-                .WillOnce(DoAll(SetArgPointee<3>(Self::HWC_DISPLAY_ID), Return(Error::NONE)));
+        EXPECT_CALL(*test->mComposer, createVirtualDisplay(Base::WIDTH, Base::HEIGHT, _, _, _))
+                .WillOnce(DoAll(SetArgPointee<4>(Self::HWC_DISPLAY_ID), Return(Error::NONE)));
         EXPECT_CALL(*test->mComposer, setClientTargetSlotCount(_)).WillOnce(Return(Error::NONE));
     }
 };
diff --git a/services/surfaceflinger/tests/unittests/FpsReporterTest.cpp b/services/surfaceflinger/tests/unittests/FpsReporterTest.cpp
index dec0ff5..010c675 100644
--- a/services/surfaceflinger/tests/unittests/FpsReporterTest.cpp
+++ b/services/surfaceflinger/tests/unittests/FpsReporterTest.cpp
@@ -76,11 +76,9 @@
     static constexpr int32_t PRIORITY_UNSET = -1;
 
     void setupScheduler();
-    void setupComposer(uint32_t virtualDisplayCount);
     sp<BufferStateLayer> createBufferStateLayer(LayerMetadata metadata);
 
     TestableSurfaceFlinger mFlinger;
-    Hwc2::mock::Composer* mComposer = nullptr;
     mock::FrameTimeline mFrameTimeline =
             mock::FrameTimeline(std::make_shared<impl::TimeStats>(), 0);
 
@@ -103,7 +101,8 @@
     ALOGD("**** Setting up for %s.%s\n", test_info->test_case_name(), test_info->name());
 
     setupScheduler();
-    setupComposer(0);
+    mFlinger.setupComposer(std::make_unique<Hwc2::mock::Composer>());
+
     mFpsListener = new TestableFpsListener();
 }
 
@@ -145,19 +144,11 @@
                             std::move(eventThread), std::move(sfEventThread));
 }
 
-void FpsReporterTest::setupComposer(uint32_t virtualDisplayCount) {
-    mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-    mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-    Mock::VerifyAndClear(mComposer);
-}
-
 namespace {
 
 TEST_F(FpsReporterTest, callsListeners) {
     mParent = createBufferStateLayer();
-    const constexpr int32_t kTaskId = 12;
+    constexpr int32_t kTaskId = 12;
     LayerMetadata targetMetadata;
     targetMetadata.setInt32(METADATA_TASK_ID, kTaskId);
     mTarget = createBufferStateLayer(targetMetadata);
diff --git a/services/surfaceflinger/tests/unittests/HWComposerTest.cpp b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
index 6b82170..138d5cb 100644
--- a/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
@@ -78,7 +78,6 @@
     const std::string kMetadata2Name = "com.example.metadata.2";
     constexpr bool kMetadata2Mandatory = true;
 
-    EXPECT_CALL(*mHal, getMaxVirtualDisplayCount()).WillOnce(Return(0));
     EXPECT_CALL(*mHal, getCapabilities()).WillOnce(Return(std::vector<hal::Capability>{}));
     EXPECT_CALL(*mHal, getLayerGenericMetadataKeys(_))
             .WillOnce(DoAll(SetArgPointee<0>(std::vector<hal::LayerGenericMetadataKey>{
@@ -101,7 +100,6 @@
 }
 
 TEST_F(HWComposerSetConfigurationTest, handlesUnsupportedCallToGetLayerGenericMetadataKeys) {
-    EXPECT_CALL(*mHal, getMaxVirtualDisplayCount()).WillOnce(Return(0));
     EXPECT_CALL(*mHal, getCapabilities()).WillOnce(Return(std::vector<hal::Capability>{}));
     EXPECT_CALL(*mHal, getLayerGenericMetadataKeys(_))
             .WillOnce(Return(hardware::graphics::composer::V2_4::Error::UNSUPPORTED));
@@ -176,4 +174,4 @@
 }
 
 } // namespace
-} // namespace android
\ No newline at end of file
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp b/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
index 9c6ad06..fd3e564 100644
--- a/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
@@ -60,7 +60,6 @@
     static constexpr int32_t PRIORITY_UNSET = -1;
 
     void setupScheduler();
-    void setupComposer(uint32_t virtualDisplayCount);
     sp<BufferQueueLayer> createBufferQueueLayer();
     sp<BufferStateLayer> createBufferStateLayer();
     sp<EffectLayer> createEffectLayer();
@@ -69,7 +68,6 @@
     void commitTransaction(Layer* layer);
 
     TestableSurfaceFlinger mFlinger;
-    Hwc2::mock::Composer* mComposer = nullptr;
 
     sp<Client> mClient;
     sp<Layer> mParent;
@@ -83,7 +81,7 @@
     ALOGD("**** Setting up for %s.%s\n", test_info->test_case_name(), test_info->name());
 
     setupScheduler();
-    setupComposer(0);
+    mFlinger.setupComposer(std::make_unique<Hwc2::mock::Composer>());
 }
 
 RefreshRateSelectionTest::~RefreshRateSelectionTest() {
@@ -147,14 +145,6 @@
                             std::move(eventThread), std::move(sfEventThread));
 }
 
-void RefreshRateSelectionTest::setupComposer(uint32_t virtualDisplayCount) {
-    mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-    mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-    Mock::VerifyAndClear(mComposer);
-}
-
 namespace {
 /* ------------------------------------------------------------------------
  * Test cases
diff --git a/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp b/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
index c088ddc..46ef750 100644
--- a/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
@@ -118,14 +118,12 @@
     SetFrameRateTest();
 
     void setupScheduler();
-    void setupComposer(uint32_t virtualDisplayCount);
 
     void addChild(sp<Layer> layer, sp<Layer> child);
     void removeChild(sp<Layer> layer, sp<Layer> child);
     void commitTransaction();
 
     TestableSurfaceFlinger mFlinger;
-    Hwc2::mock::Composer* mComposer = nullptr;
     mock::MessageQueue* mMessageQueue = new mock::MessageQueue();
 
     std::vector<sp<Layer>> mLayers;
@@ -139,10 +137,11 @@
     mFlinger.mutableUseFrameRateApi() = true;
 
     setupScheduler();
-    setupComposer(0);
 
+    mFlinger.setupComposer(std::make_unique<Hwc2::mock::Composer>());
     mFlinger.mutableEventQueue().reset(mMessageQueue);
 }
+
 void SetFrameRateTest::addChild(sp<Layer> layer, sp<Layer> child) {
     layer.get()->addChild(child.get());
 }
@@ -184,14 +183,6 @@
                             /*hasMultipleModes*/ true);
 }
 
-void SetFrameRateTest::setupComposer(uint32_t virtualDisplayCount) {
-    mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-    mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-    Mock::VerifyAndClear(mComposer);
-}
-
 namespace {
 /* ------------------------------------------------------------------------
  * Test cases
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index d004b9d..f95b878 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -42,7 +42,6 @@
 #include "SurfaceInterceptor.h"
 #include "TestableScheduler.h"
 #include "mock/DisplayHardware/MockComposer.h"
-#include "mock/MockDisplayIdGenerator.h"
 #include "mock/MockFrameTimeline.h"
 #include "mock/MockFrameTracer.h"
 
@@ -185,9 +184,6 @@
 
     SurfaceFlinger* flinger() { return mFlinger.get(); }
     TestableScheduler* scheduler() { return mScheduler; }
-    mock::DisplayIdGenerator<GpuVirtualDisplayId>& gpuVirtualDisplayIdGenerator() {
-        return mGpuVirtualDisplayIdGenerator;
-    }
 
     // Extend this as needed for accessing SurfaceFlinger private (and public)
     // functions.
@@ -308,6 +304,8 @@
         return mFlinger->destroyDisplay(displayToken);
     }
 
+    void enableHalVirtualDisplays(bool enable) { mFlinger->enableHalVirtualDisplays(enable); }
+
     auto setupNewDisplayDeviceInternal(
             const wp<IBinder>& displayToken,
             std::shared_ptr<compositionengine::Display> compositionDisplay,
@@ -436,7 +434,6 @@
     auto& mutablePhysicalDisplayTokens() { return mFlinger->mPhysicalDisplayTokens; }
     auto& mutableTexturePool() { return mFlinger->mTexturePool; }
     auto& mutableTransactionFlags() { return mFlinger->mTransactionFlags; }
-    auto& mutableUseHwcVirtualDisplays() { return mFlinger->mUseHwcVirtualDisplays; }
     auto& mutablePowerAdvisor() { return mFlinger->mPowerAdvisor; }
     auto& mutableDebugDisableHWC() { return mFlinger->mDebugDisableHWC; }
 
@@ -775,7 +772,6 @@
     surfaceflinger::test::Factory mFactory;
     sp<SurfaceFlinger> mFlinger = new SurfaceFlinger(mFactory, SurfaceFlinger::SkipInitialization);
     TestableScheduler* mScheduler = nullptr;
-    mock::DisplayIdGenerator<GpuVirtualDisplayId> mGpuVirtualDisplayIdGenerator;
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp b/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
index 25001d3..546bc4a 100644
--- a/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionFrameTracerTest.cpp
@@ -45,7 +45,7 @@
                 ::testing::UnitTest::GetInstance()->current_test_info();
         ALOGD("**** Setting up for %s.%s\n", test_info->test_case_name(), test_info->name());
         setupScheduler();
-        setupComposer(0);
+        mFlinger.setupComposer(std::make_unique<Hwc2::mock::Composer>());
     }
 
     ~TransactionFrameTracerTest() {
@@ -91,17 +91,9 @@
                                 std::move(eventThread), std::move(sfEventThread));
     }
 
-    void setupComposer(uint32_t virtualDisplayCount) {
-        mComposer = new Hwc2::mock::Composer();
-        EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-        mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-        Mock::VerifyAndClear(mComposer);
-    }
-
     TestableSurfaceFlinger mFlinger;
-    Hwc2::mock::Composer* mComposer = nullptr;
     renderengine::mock::RenderEngine mRenderEngine;
+
     FenceToFenceTimeMap fenceFactory;
     client_cache_t mClientCache;
 
diff --git a/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp b/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
index b7917aa..c1123cd 100644
--- a/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionSurfaceFrameTest.cpp
@@ -45,7 +45,7 @@
                 ::testing::UnitTest::GetInstance()->current_test_info();
         ALOGD("**** Setting up for %s.%s\n", test_info->test_case_name(), test_info->name());
         setupScheduler();
-        setupComposer(0);
+        mFlinger.setupComposer(std::make_unique<Hwc2::mock::Composer>());
     }
 
     ~TransactionSurfaceFrameTest() {
@@ -91,17 +91,9 @@
                                 std::move(eventThread), std::move(sfEventThread));
     }
 
-    void setupComposer(uint32_t virtualDisplayCount) {
-        mComposer = new Hwc2::mock::Composer();
-        EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
-        mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
-
-        Mock::VerifyAndClear(mComposer);
-    }
-
     TestableSurfaceFlinger mFlinger;
-    Hwc2::mock::Composer* mComposer = nullptr;
     renderengine::mock::RenderEngine mRenderEngine;
+
     FenceToFenceTimeMap fenceFactory;
     client_cache_t mClientCache;
 
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
index 1ba3c0f..cb3bd73 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
@@ -54,7 +54,8 @@
     MOCK_METHOD0(resetCommands, void());
     MOCK_METHOD0(executeCommands, Error());
     MOCK_METHOD0(getMaxVirtualDisplayCount, uint32_t());
-    MOCK_METHOD4(createVirtualDisplay, Error(uint32_t, uint32_t, PixelFormat*, Display*));
+    MOCK_METHOD5(createVirtualDisplay,
+                 Error(uint32_t, uint32_t, PixelFormat*, std::optional<Display>, Display*));
     MOCK_METHOD1(destroyVirtualDisplay, Error(Display));
     MOCK_METHOD1(acceptDisplayChanges, Error(Display));
     MOCK_METHOD2(createLayer, Error(Display, Layer* outLayer));
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h b/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h
deleted file mode 100644
index cfc37ea..0000000
--- a/services/surfaceflinger/tests/unittests/mock/MockDisplayIdGenerator.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- * Copyright 2020 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-#include <gmock/gmock.h>
-
-#include "DisplayIdGenerator.h"
-
-namespace android::mock {
-
-template <typename T>
-class DisplayIdGenerator : public android::DisplayIdGenerator<T> {
-public:
-    // Explicit default instantiation is recommended.
-    DisplayIdGenerator() = default;
-    virtual ~DisplayIdGenerator() = default;
-
-    MOCK_METHOD0(nextId, std::optional<T>());
-    MOCK_METHOD1(markUnused, void(T));
-};
-
-} // namespace android::mock