diff --git a/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp b/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
index 0e41962..eff5130 100644
--- a/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/AidlComposerHal.cpp
@@ -230,6 +230,8 @@
         return;
     }
 
+    addReader(translate<Display>(kSingleReaderKey));
+
     ALOGI("Loaded AIDL composer3 HAL service");
 }
 
@@ -298,12 +300,19 @@
     }
 }
 
-void AidlComposer::resetCommands() {
-    mWriter.reset();
+void AidlComposer::resetCommands(Display display) {
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().reset();
+    }
+    mMutex.unlock_shared();
 }
 
-Error AidlComposer::executeCommands() {
-    return execute();
+Error AidlComposer::executeCommands(Display display) {
+    mMutex.lock_shared();
+    auto error = execute(display);
+    mMutex.unlock_shared();
+    return error;
 }
 
 uint32_t AidlComposer::getMaxVirtualDisplayCount() {
@@ -334,6 +343,7 @@
 
     *outDisplay = translate<Display>(virtualDisplay.display);
     *format = static_cast<PixelFormat>(virtualDisplay.format);
+    addDisplay(translate<Display>(virtualDisplay.display));
     return Error::NONE;
 }
 
@@ -343,12 +353,20 @@
         ALOGE("destroyVirtualDisplay failed %s", status.getDescription().c_str());
         return static_cast<Error>(status.getServiceSpecificError());
     }
+    removeDisplay(display);
     return Error::NONE;
 }
 
 Error AidlComposer::acceptDisplayChanges(Display display) {
-    mWriter.acceptDisplayChanges(translate<int64_t>(display));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().acceptDisplayChanges(translate<int64_t>(display));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::createLayer(Display display, Layer* outLayer) {
@@ -388,7 +406,17 @@
 Error AidlComposer::getChangedCompositionTypes(
         Display display, std::vector<Layer>* outLayers,
         std::vector<aidl::android::hardware::graphics::composer3::Composition>* outTypes) {
-    const auto changedLayers = mReader.takeChangedCompositionTypes(translate<int64_t>(display));
+    std::vector<ChangedCompositionLayer> changedLayers;
+    Error error = Error::NONE;
+    {
+        mMutex.lock_shared();
+        if (auto reader = getReader(display)) {
+            changedLayers = reader->get().takeChangedCompositionTypes(translate<int64_t>(display));
+        } else {
+            error = Error::BAD_DISPLAY;
+        }
+        mMutex.unlock_shared();
+    }
     outLayers->reserve(changedLayers.size());
     outTypes->reserve(changedLayers.size());
 
@@ -396,7 +424,7 @@
         outLayers->emplace_back(translate<Layer>(layer.layer));
         outTypes->emplace_back(layer.composition);
     }
-    return Error::NONE;
+    return error;
 }
 
 Error AidlComposer::getColorModes(Display display, std::vector<ColorMode>* outModes) {
@@ -448,7 +476,17 @@
 Error AidlComposer::getDisplayRequests(Display display, uint32_t* outDisplayRequestMask,
                                        std::vector<Layer>* outLayers,
                                        std::vector<uint32_t>* outLayerRequestMasks) {
-    const auto displayRequests = mReader.takeDisplayRequests(translate<int64_t>(display));
+    Error error = Error::NONE;
+    DisplayRequest displayRequests;
+    {
+        mMutex.lock_shared();
+        if (auto reader = getReader(display)) {
+            displayRequests = reader->get().takeDisplayRequests(translate<int64_t>(display));
+        } else {
+            error = Error::BAD_DISPLAY;
+        }
+        mMutex.unlock_shared();
+    }
     *outDisplayRequestMask = translate<uint32_t>(displayRequests.mask);
     outLayers->reserve(displayRequests.layerRequests.size());
     outLayerRequestMasks->reserve(displayRequests.layerRequests.size());
@@ -457,7 +495,7 @@
         outLayers->emplace_back(translate<Layer>(layer.layer));
         outLayerRequestMasks->emplace_back(translate<uint32_t>(layer.mask));
     }
-    return Error::NONE;
+    return error;
 }
 
 Error AidlComposer::getDozeSupport(Display display, bool* outSupport) {
@@ -511,7 +549,17 @@
 
 Error AidlComposer::getReleaseFences(Display display, std::vector<Layer>* outLayers,
                                      std::vector<int>* outReleaseFences) {
-    auto fences = mReader.takeReleaseFences(translate<int64_t>(display));
+    Error error = Error::NONE;
+    std::vector<ReleaseFences::Layer> fences;
+    {
+        mMutex.lock_shared();
+        if (auto reader = getReader(display)) {
+            fences = reader->get().takeReleaseFences(translate<int64_t>(display));
+        } else {
+            error = Error::BAD_DISPLAY;
+        }
+        mMutex.unlock_shared();
+    }
     outLayers->reserve(fences.size());
     outReleaseFences->reserve(fences.size());
 
@@ -522,19 +570,29 @@
         *fence.fence.getR() = -1;
         outReleaseFences->emplace_back(fenceOwner);
     }
-    return Error::NONE;
+    return error;
 }
 
 Error AidlComposer::presentDisplay(Display display, int* outPresentFence) {
     ATRACE_NAME("HwcPresentDisplay");
-    mWriter.presentDisplay(translate<int64_t>(display));
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    auto writer = getWriter(display);
+    auto reader = getReader(display);
+    if (writer && reader) {
+        writer->get().presentDisplay(translate<int64_t>(display));
+        error = execute(display);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
 
-    Error error = execute();
     if (error != Error::NONE) {
+        mMutex.unlock_shared();
         return error;
     }
 
-    auto fence = mReader.takePresentFence(translate<int64_t>(display));
+    auto fence = reader->get().takePresentFence(translate<int64_t>(display));
+    mMutex.unlock_shared();
     // take ownership
     *outPresentFence = fence.get();
     *fence.getR() = -1;
@@ -559,11 +617,19 @@
         handle = target->getNativeBuffer()->handle;
     }
 
-    mWriter.setClientTarget(translate<int64_t>(display), slot, handle, acquireFence,
-                            translate<aidl::android::hardware::graphics::common::Dataspace>(
-                                    dataspace),
-                            translate<AidlRect>(damage));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get()
+                .setClientTarget(translate<int64_t>(display), slot, handle, acquireFence,
+                                 translate<aidl::android::hardware::graphics::common::Dataspace>(
+                                         dataspace),
+                                 translate<AidlRect>(damage));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setColorMode(Display display, ColorMode mode, RenderIntent renderIntent) {
@@ -579,14 +645,28 @@
 }
 
 Error AidlComposer::setColorTransform(Display display, const float* matrix) {
-    mWriter.setColorTransform(translate<int64_t>(display), matrix);
-    return Error::NONE;
+    auto error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setColorTransform(translate<int64_t>(display), matrix);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setOutputBuffer(Display display, const native_handle_t* buffer,
                                     int releaseFence) {
-    mWriter.setOutputBuffer(translate<int64_t>(display), 0, buffer, dup(releaseFence));
-    return Error::NONE;
+    auto error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setOutputBuffer(translate<int64_t>(display), 0, buffer, dup(releaseFence));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setPowerMode(Display display, IComposerClient::PowerMode mode) {
@@ -624,16 +704,26 @@
 Error AidlComposer::validateDisplay(Display display, nsecs_t expectedPresentTime,
                                     uint32_t* outNumTypes, uint32_t* outNumRequests) {
     ATRACE_NAME("HwcValidateDisplay");
-    mWriter.validateDisplay(translate<int64_t>(display),
-                            ClockMonotonicTimestamp{expectedPresentTime});
+    const auto displayId = translate<int64_t>(display);
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    auto writer = getWriter(display);
+    auto reader = getReader(display);
+    if (writer && reader) {
+        writer->get().validateDisplay(displayId, ClockMonotonicTimestamp{expectedPresentTime});
+        error = execute(display);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
 
-    Error error = execute();
     if (error != Error::NONE) {
+        mMutex.unlock_shared();
         return error;
     }
 
-    mReader.hasChanges(translate<int64_t>(display), outNumTypes, outNumRequests);
+    reader->get().hasChanges(displayId, outNumTypes, outNumRequests);
 
+    mMutex.unlock_shared();
     return Error::NONE;
 }
 
@@ -641,39 +731,59 @@
                                              uint32_t* outNumTypes, uint32_t* outNumRequests,
                                              int* outPresentFence, uint32_t* state) {
     ATRACE_NAME("HwcPresentOrValidateDisplay");
-    mWriter.presentOrvalidateDisplay(translate<int64_t>(display),
-                                     ClockMonotonicTimestamp{expectedPresentTime});
+    const auto displayId = translate<int64_t>(display);
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    auto writer = getWriter(display);
+    auto reader = getReader(display);
+    if (writer && reader) {
+        writer->get().presentOrvalidateDisplay(displayId,
+                                               ClockMonotonicTimestamp{expectedPresentTime});
+        error = execute(display);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
 
-    Error error = execute();
     if (error != Error::NONE) {
+        mMutex.unlock_shared();
         return error;
     }
 
-    const auto result = mReader.takePresentOrValidateStage(translate<int64_t>(display));
+    const auto result = reader->get().takePresentOrValidateStage(displayId);
     if (!result.has_value()) {
         *state = translate<uint32_t>(-1);
+        mMutex.unlock_shared();
         return Error::NO_RESOURCES;
     }
 
     *state = translate<uint32_t>(*result);
 
     if (*result == PresentOrValidate::Result::Presented) {
-        auto fence = mReader.takePresentFence(translate<int64_t>(display));
+        auto fence = reader->get().takePresentFence(displayId);
         // take ownership
         *outPresentFence = fence.get();
         *fence.getR() = -1;
     }
 
     if (*result == PresentOrValidate::Result::Validated) {
-        mReader.hasChanges(translate<int64_t>(display), outNumTypes, outNumRequests);
+        reader->get().hasChanges(displayId, outNumTypes, outNumRequests);
     }
 
+    mMutex.unlock_shared();
     return Error::NONE;
 }
 
 Error AidlComposer::setCursorPosition(Display display, Layer layer, int32_t x, int32_t y) {
-    mWriter.setLayerCursorPosition(translate<int64_t>(display), translate<int64_t>(layer), x, y);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerCursorPosition(translate<int64_t>(display), translate<int64_t>(layer),
+                                             x, y);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerBuffer(Display display, Layer layer, uint32_t slot,
@@ -683,90 +793,190 @@
         handle = buffer->getNativeBuffer()->handle;
     }
 
-    mWriter.setLayerBuffer(translate<int64_t>(display), translate<int64_t>(layer), slot, handle,
-                           acquireFence);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerBuffer(translate<int64_t>(display), translate<int64_t>(layer), slot,
+                                     handle, acquireFence);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerSurfaceDamage(Display display, Layer layer,
                                           const std::vector<IComposerClient::Rect>& damage) {
-    mWriter.setLayerSurfaceDamage(translate<int64_t>(display), translate<int64_t>(layer),
-                                  translate<AidlRect>(damage));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerSurfaceDamage(translate<int64_t>(display), translate<int64_t>(layer),
+                                            translate<AidlRect>(damage));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerBlendMode(Display display, Layer layer,
                                       IComposerClient::BlendMode mode) {
-    mWriter.setLayerBlendMode(translate<int64_t>(display), translate<int64_t>(layer),
-                              translate<BlendMode>(mode));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerBlendMode(translate<int64_t>(display), translate<int64_t>(layer),
+                                        translate<BlendMode>(mode));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerColor(Display display, Layer layer, const Color& color) {
-    mWriter.setLayerColor(translate<int64_t>(display), translate<int64_t>(layer), color);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerColor(translate<int64_t>(display), translate<int64_t>(layer), color);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerCompositionType(
         Display display, Layer layer,
         aidl::android::hardware::graphics::composer3::Composition type) {
-    mWriter.setLayerCompositionType(translate<int64_t>(display), translate<int64_t>(layer), type);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerCompositionType(translate<int64_t>(display),
+                                              translate<int64_t>(layer), type);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerDataspace(Display display, Layer layer, Dataspace dataspace) {
-    mWriter.setLayerDataspace(translate<int64_t>(display), translate<int64_t>(layer),
-                              translate<AidlDataspace>(dataspace));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerDataspace(translate<int64_t>(display), translate<int64_t>(layer),
+                                        translate<AidlDataspace>(dataspace));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerDisplayFrame(Display display, Layer layer,
                                          const IComposerClient::Rect& frame) {
-    mWriter.setLayerDisplayFrame(translate<int64_t>(display), translate<int64_t>(layer),
-                                 translate<AidlRect>(frame));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerDisplayFrame(translate<int64_t>(display), translate<int64_t>(layer),
+                                           translate<AidlRect>(frame));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerPlaneAlpha(Display display, Layer layer, float alpha) {
-    mWriter.setLayerPlaneAlpha(translate<int64_t>(display), translate<int64_t>(layer), alpha);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerPlaneAlpha(translate<int64_t>(display), translate<int64_t>(layer),
+                                         alpha);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerSidebandStream(Display display, Layer layer,
                                            const native_handle_t* stream) {
-    mWriter.setLayerSidebandStream(translate<int64_t>(display), translate<int64_t>(layer), stream);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerSidebandStream(translate<int64_t>(display), translate<int64_t>(layer),
+                                             stream);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerSourceCrop(Display display, Layer layer,
                                        const IComposerClient::FRect& crop) {
-    mWriter.setLayerSourceCrop(translate<int64_t>(display), translate<int64_t>(layer),
-                               translate<AidlFRect>(crop));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerSourceCrop(translate<int64_t>(display), translate<int64_t>(layer),
+                                         translate<AidlFRect>(crop));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerTransform(Display display, Layer layer, Transform transform) {
-    mWriter.setLayerTransform(translate<int64_t>(display), translate<int64_t>(layer),
-                              translate<AidlTransform>(transform));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerTransform(translate<int64_t>(display), translate<int64_t>(layer),
+                                        translate<AidlTransform>(transform));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerVisibleRegion(Display display, Layer layer,
                                           const std::vector<IComposerClient::Rect>& visible) {
-    mWriter.setLayerVisibleRegion(translate<int64_t>(display), translate<int64_t>(layer),
-                                  translate<AidlRect>(visible));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerVisibleRegion(translate<int64_t>(display), translate<int64_t>(layer),
+                                            translate<AidlRect>(visible));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerZOrder(Display display, Layer layer, uint32_t z) {
-    mWriter.setLayerZOrder(translate<int64_t>(display), translate<int64_t>(layer), z);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerZOrder(translate<int64_t>(display), translate<int64_t>(layer), z);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
-Error AidlComposer::execute() {
-    const auto& commands = mWriter.getPendingCommands();
+Error AidlComposer::execute(Display display) {
+    auto writer = getWriter(display);
+    auto reader = getReader(display);
+    if (!writer || !reader) {
+        return Error::BAD_DISPLAY;
+    }
+
+    const auto& commands = writer->get().getPendingCommands();
     if (commands.empty()) {
-        mWriter.reset();
+        writer->get().reset();
         return Error::NONE;
     }
 
@@ -778,9 +988,9 @@
             return static_cast<Error>(status.getServiceSpecificError());
         }
 
-        mReader.parse(std::move(results));
+        reader->get().parse(std::move(results));
     }
-    const auto commandErrors = mReader.takeErrors();
+    const auto commandErrors = reader->get().takeErrors();
     Error error = Error::NONE;
     for (const auto& cmdErr : commandErrors) {
         const auto index = static_cast<size_t>(cmdErr.commandIndex);
@@ -798,7 +1008,7 @@
         }
     }
 
-    mWriter.reset();
+    writer->get().reset();
 
     return error;
 }
@@ -806,9 +1016,17 @@
 Error AidlComposer::setLayerPerFrameMetadata(
         Display display, Layer layer,
         const std::vector<IComposerClient::PerFrameMetadata>& perFrameMetadatas) {
-    mWriter.setLayerPerFrameMetadata(translate<int64_t>(display), translate<int64_t>(layer),
-                                     translate<AidlPerFrameMetadata>(perFrameMetadatas));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerPerFrameMetadata(translate<int64_t>(display),
+                                               translate<int64_t>(layer),
+                                               translate<AidlPerFrameMetadata>(perFrameMetadatas));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 std::vector<IComposerClient::PerFrameMetadataKey> AidlComposer::getPerFrameMetadataKeys(
@@ -868,8 +1086,16 @@
 }
 
 Error AidlComposer::setLayerColorTransform(Display display, Layer layer, const float* matrix) {
-    mWriter.setLayerColorTransform(translate<int64_t>(display), translate<int64_t>(layer), matrix);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerColorTransform(translate<int64_t>(display), translate<int64_t>(layer),
+                                             matrix);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::getDisplayedContentSamplingAttributes(Display display, PixelFormat* outFormat,
@@ -932,20 +1158,36 @@
 Error AidlComposer::setLayerPerFrameMetadataBlobs(
         Display display, Layer layer,
         const std::vector<IComposerClient::PerFrameMetadataBlob>& metadata) {
-    mWriter.setLayerPerFrameMetadataBlobs(translate<int64_t>(display), translate<int64_t>(layer),
-                                          translate<AidlPerFrameMetadataBlob>(metadata));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerPerFrameMetadataBlobs(translate<int64_t>(display),
+                                                    translate<int64_t>(layer),
+                                                    translate<AidlPerFrameMetadataBlob>(metadata));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setDisplayBrightness(Display display, float brightness, float brightnessNits,
                                          const DisplayBrightnessOptions& options) {
-    mWriter.setDisplayBrightness(translate<int64_t>(display), brightness, brightnessNits);
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setDisplayBrightness(translate<int64_t>(display), brightness, brightnessNits);
 
-    if (options.applyImmediately) {
-        return execute();
+        if (options.applyImmediately) {
+            error = execute(display);
+            mMutex.unlock_shared();
+            return error;
+        }
+    } else {
+        error = Error::BAD_DISPLAY;
     }
-
-    return Error::NONE;
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::getDisplayCapabilities(Display display,
@@ -1085,20 +1327,43 @@
 
 Error AidlComposer::getClientTargetProperty(
         Display display, ClientTargetPropertyWithBrightness* outClientTargetProperty) {
-    *outClientTargetProperty = mReader.takeClientTargetProperty(translate<int64_t>(display));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto reader = getReader(display)) {
+        *outClientTargetProperty =
+                reader->get().takeClientTargetProperty(translate<int64_t>(display));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerBrightness(Display display, Layer layer, float brightness) {
-    mWriter.setLayerBrightness(translate<int64_t>(display), translate<int64_t>(layer), brightness);
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerBrightness(translate<int64_t>(display), translate<int64_t>(layer),
+                                         brightness);
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::setLayerBlockingRegion(Display display, Layer layer,
                                            const std::vector<IComposerClient::Rect>& blocking) {
-    mWriter.setLayerBlockingRegion(translate<int64_t>(display), translate<int64_t>(layer),
-                                   translate<AidlRect>(blocking));
-    return Error::NONE;
+    Error error = Error::NONE;
+    mMutex.lock_shared();
+    if (auto writer = getWriter(display)) {
+        writer->get().setLayerBlockingRegion(translate<int64_t>(display), translate<int64_t>(layer),
+                                             translate<AidlRect>(blocking));
+    } else {
+        error = Error::BAD_DISPLAY;
+    }
+    mMutex.unlock_shared();
+    return error;
 }
 
 Error AidlComposer::getDisplayDecorationSupport(Display display,
@@ -1136,5 +1401,88 @@
     return Error::NONE;
 }
 
+ftl::Optional<std::reference_wrapper<ComposerClientWriter>> AidlComposer::getWriter(Display display)
+        REQUIRES_SHARED(mMutex) {
+    return mWriters.get(display);
+}
+
+ftl::Optional<std::reference_wrapper<ComposerClientReader>> AidlComposer::getReader(Display display)
+        REQUIRES_SHARED(mMutex) {
+    if (mSingleReader) {
+        display = translate<Display>(kSingleReaderKey);
+    }
+    return mReaders.get(display);
+}
+
+void AidlComposer::removeDisplay(Display display) {
+    mMutex.lock();
+    bool wasErased = mWriters.erase(display);
+    ALOGW_IF(!wasErased,
+             "Attempting to remove writer for display %" PRId64 " which is not connected",
+             translate<int64_t>(display));
+    if (!mSingleReader) {
+        removeReader(display);
+    }
+    mMutex.unlock();
+}
+
+void AidlComposer::onHotplugDisconnect(Display display) {
+    removeDisplay(display);
+}
+
+bool AidlComposer::hasMultiThreadedPresentSupport(Display display) {
+    const auto displayId = translate<int64_t>(display);
+    std::vector<AidlDisplayCapability> capabilities;
+    const auto status = mAidlComposerClient->getDisplayCapabilities(displayId, &capabilities);
+    if (!status.isOk()) {
+        ALOGE("getDisplayCapabilities failed %s", status.getDescription().c_str());
+        return false;
+    }
+    return std::find(capabilities.begin(), capabilities.end(),
+                     AidlDisplayCapability::MULTI_THREADED_PRESENT) != capabilities.end();
+}
+
+void AidlComposer::addReader(Display display) {
+    const auto displayId = translate<int64_t>(display);
+    std::optional<int64_t> displayOpt;
+    if (displayId != kSingleReaderKey) {
+        displayOpt.emplace(displayId);
+    }
+    auto [it, added] = mReaders.try_emplace(display, std::move(displayOpt));
+    ALOGW_IF(!added, "Attempting to add writer for display %" PRId64 " which is already connected",
+             displayId);
+}
+
+void AidlComposer::removeReader(Display display) {
+    bool wasErased = mReaders.erase(display);
+    ALOGW_IF(!wasErased,
+             "Attempting to remove reader for display %" PRId64 " which is not connected",
+             translate<int64_t>(display));
+}
+
+void AidlComposer::addDisplay(Display display) {
+    const auto displayId = translate<int64_t>(display);
+    mMutex.lock();
+    auto [it, added] = mWriters.try_emplace(display, displayId);
+    ALOGW_IF(!added, "Attempting to add writer for display %" PRId64 " which is already connected",
+             displayId);
+    if (mSingleReader) {
+        if (hasMultiThreadedPresentSupport(display)) {
+            mSingleReader = false;
+            removeReader(translate<Display>(kSingleReaderKey));
+            // Note that this includes the new display.
+            for (const auto& [existingDisplay, _] : mWriters) {
+                addReader(existingDisplay);
+            }
+        }
+    } else {
+        addReader(display);
+    }
+    mMutex.unlock();
+}
+
+void AidlComposer::onHotplugConnect(Display display) {
+    addDisplay(display);
+}
 } // namespace Hwc2
 } // namespace android
diff --git a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
index f2a59a5..d84efe7 100644
--- a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
@@ -17,10 +17,12 @@
 #pragma once
 
 #include "ComposerHal.h"
+#include <ftl/shared_mutex.h>
+#include <ftl/small_map.h>
 
+#include <functional>
 #include <optional>
 #include <string>
-#include <unordered_map>
 #include <utility>
 #include <vector>
 
@@ -70,10 +72,10 @@
 
     // Reset all pending commands in the command buffer. Useful if you want to
     // skip a frame but have already queued some commands.
-    void resetCommands() override;
+    void resetCommands(Display) override;
 
     // Explicitly flush all pending commands in the command buffer.
-    Error executeCommands() override;
+    Error executeCommands(Display) override;
 
     uint32_t getMaxVirtualDisplayCount() override;
     Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
@@ -228,16 +230,29 @@
 
     Error getPhysicalDisplayOrientation(Display displayId,
                                         AidlTransform* outDisplayOrientation) override;
+    void onHotplugConnect(Display) override;
+    void onHotplugDisconnect(Display) override;
 
 private:
     // Many public functions above simply write a command into the command
     // queue to batch the calls.  validateDisplay and presentDisplay will call
     // this function to execute the command queue.
-    Error execute();
+    Error execute(Display) REQUIRES_SHARED(mMutex);
 
     // returns the default instance name for the given service
     static std::string instance(const std::string& serviceName);
 
+    ftl::Optional<std::reference_wrapper<ComposerClientWriter>> getWriter(Display)
+            REQUIRES_SHARED(mMutex);
+    ftl::Optional<std::reference_wrapper<ComposerClientReader>> getReader(Display)
+            REQUIRES_SHARED(mMutex);
+    void addDisplay(Display) EXCLUDES(mMutex);
+    void removeDisplay(Display) EXCLUDES(mMutex);
+    void addReader(Display) REQUIRES(mMutex);
+    void removeReader(Display) REQUIRES(mMutex);
+
+    bool hasMultiThreadedPresentSupport(Display);
+
     // 64KiB minus a small space for metadata such as read/write pointers
     static constexpr size_t kWriterInitialSize = 64 * 1024 / sizeof(uint32_t) - 16;
     // Max number of buffers that may be cached for a given layer
@@ -245,8 +260,25 @@
     // 1. Tightly coupling this cache to the max size of BufferQueue
     // 2. Adding an additional slot for the layer caching feature in SurfaceFlinger (see: Planner.h)
     static const constexpr uint32_t kMaxLayerBufferCount = BufferQueue::NUM_BUFFER_SLOTS + 1;
-    ComposerClientWriter mWriter;
-    ComposerClientReader mReader;
+
+    // Without DisplayCapability::MULTI_THREADED_PRESENT, we use a single reader
+    // for all displays. With the capability, we use a separate reader for each
+    // display.
+    bool mSingleReader = true;
+    // Invalid displayId used as a key to mReaders when mSingleReader is true.
+    static constexpr int64_t kSingleReaderKey = 0;
+
+    // TODO (b/256881188): Use display::PhysicalDisplayMap instead of hard-coded `3`
+    ftl::SmallMap<Display, ComposerClientWriter, 3> mWriters GUARDED_BY(mMutex);
+    ftl::SmallMap<Display, ComposerClientReader, 3> mReaders GUARDED_BY(mMutex);
+    // Protect access to mWriters and mReaders with a shared_mutex. Adding and
+    // removing a display require exclusive access, since the iterator or the
+    // writer/reader may be invalidated. Other calls need shared access while
+    // using the writer/reader, so they can use their display's writer/reader
+    // without it being deleted or the iterator being invalidated.
+    // TODO (b/257958323): Use std::shared_mutex and RAII once they support
+    // threading annotations.
+    ftl::SharedMutex mMutex;
 
     // Aidl interface
     using AidlIComposer = aidl::android::hardware::graphics::composer3::IComposer;
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.h b/services/surfaceflinger/DisplayHardware/ComposerHal.h
index b02f867..a9bf282 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.h
@@ -110,10 +110,10 @@
 
     // Reset all pending commands in the command buffer. Useful if you want to
     // skip a frame but have already queued some commands.
-    virtual void resetCommands() = 0;
+    virtual void resetCommands(Display) = 0;
 
     // Explicitly flush all pending commands in the command buffer.
-    virtual Error executeCommands() = 0;
+    virtual Error executeCommands(Display) = 0;
 
     virtual uint32_t getMaxVirtualDisplayCount() = 0;
     virtual Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat*,
@@ -283,6 +283,8 @@
     virtual Error getPhysicalDisplayOrientation(Display displayId,
                                                 AidlTransform* outDisplayOrientation) = 0;
     virtual Error getOverlaySupport(V3_0::OverlayProperties* outProperties) = 0;
+    virtual void onHotplugConnect(Display) = 0;
+    virtual void onHotplugDisconnect(Display) = 0;
 };
 
 } // namespace Hwc2
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 168e2dd..5f11cb8 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -513,7 +513,7 @@
 
     if (displayData.validateWasSkipped) {
         // explicitly flush all pending commands
-        auto error = static_cast<hal::Error>(mComposer->executeCommands());
+        auto error = static_cast<hal::Error>(mComposer->executeCommands(hwcDisplay->getId()));
         RETURN_IF_HWC_ERROR_FOR("executeCommands", error, displayId, UNKNOWN_ERROR);
         RETURN_IF_HWC_ERROR_FOR("present", displayData.presentError, displayId, UNKNOWN_ERROR);
         return NO_ERROR;
@@ -933,6 +933,8 @@
                                                                : "Secondary display",
                                              .deviceProductInfo = std::nullopt};
         }();
+
+        mComposer->onHotplugConnect(hwcDisplayId);
     }
 
     if (!isConnected(info->id)) {
@@ -960,6 +962,7 @@
     // The display will later be destroyed by a call to HWComposer::disconnectDisplay. For now, mark
     // it as disconnected.
     mDisplayData.at(*displayId).hwcDisplay->setConnected(false);
+    mComposer->onHotplugDisconnect(hwcDisplayId);
     return DisplayIdentificationInfo{.id = *displayId};
 }
 
diff --git a/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp b/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
index a664d2c..f8522e2 100644
--- a/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/HidlComposerHal.cpp
@@ -273,11 +273,11 @@
     }
 }
 
-void HidlComposer::resetCommands() {
+void HidlComposer::resetCommands(Display) {
     mWriter.reset();
 }
 
-Error HidlComposer::executeCommands() {
+Error HidlComposer::executeCommands(Display) {
     return execute();
 }
 
@@ -1357,6 +1357,9 @@
     registerCallback(sp<ComposerCallbackBridge>::make(callback, vsyncSwitchingSupported));
 }
 
+void HidlComposer::onHotplugConnect(Display) {}
+void HidlComposer::onHotplugDisconnect(Display) {}
+
 CommandReader::~CommandReader() {
     resetData();
 }
diff --git a/services/surfaceflinger/DisplayHardware/HidlComposerHal.h b/services/surfaceflinger/DisplayHardware/HidlComposerHal.h
index b436408..48b720c 100644
--- a/services/surfaceflinger/DisplayHardware/HidlComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/HidlComposerHal.h
@@ -177,10 +177,10 @@
 
     // Reset all pending commands in the command buffer. Useful if you want to
     // skip a frame but have already queued some commands.
-    void resetCommands() override;
+    void resetCommands(Display) override;
 
     // Explicitly flush all pending commands in the command buffer.
-    Error executeCommands() override;
+    Error executeCommands(Display) override;
 
     uint32_t getMaxVirtualDisplayCount() override;
     Error createVirtualDisplay(uint32_t width, uint32_t height, PixelFormat* format,
@@ -339,6 +339,8 @@
 
     Error getPhysicalDisplayOrientation(Display displayId,
                                         AidlTransform* outDisplayOrientation) override;
+    void onHotplugConnect(Display) override;
+    void onHotplugDisconnect(Display) override;
 
 private:
     class CommandWriter : public CommandWriterBase {
diff --git a/services/surfaceflinger/fuzzer/surfaceflinger_displayhardware_fuzzer.cpp b/services/surfaceflinger/fuzzer/surfaceflinger_displayhardware_fuzzer.cpp
index f8fc6f5..8a6af10 100644
--- a/services/surfaceflinger/fuzzer/surfaceflinger_displayhardware_fuzzer.cpp
+++ b/services/surfaceflinger/fuzzer/surfaceflinger_displayhardware_fuzzer.cpp
@@ -326,8 +326,8 @@
     invokeComposerHal2_3(&composer, display, outLayer);
     invokeComposerHal2_4(&composer, display, outLayer);
 
-    composer.executeCommands();
-    composer.resetCommands();
+    composer.executeCommands(display);
+    composer.resetCommands(display);
 
     composer.destroyLayer(display, outLayer);
     composer.destroyVirtualDisplay(display);
diff --git a/services/surfaceflinger/tests/unittests/HWComposerTest.cpp b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
index 9d8e0a2..342c646 100644
--- a/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
@@ -73,6 +73,7 @@
 
         EXPECT_CALL(*mHal, setClientTargetSlotCount(_));
         EXPECT_CALL(*mHal, setVsyncEnabled(hwcDisplayId, Hwc2::IComposerClient::Vsync::DISABLE));
+        EXPECT_CALL(*mHal, onHotplugConnect(hwcDisplayId));
     }
 };
 
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
index 3808487..5ee38ec 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
@@ -56,8 +56,8 @@
                  std::vector<aidl::android::hardware::graphics::composer3::Capability>());
     MOCK_METHOD0(dumpDebugInfo, std::string());
     MOCK_METHOD1(registerCallback, void(HWC2::ComposerCallback&));
-    MOCK_METHOD0(resetCommands, void());
-    MOCK_METHOD0(executeCommands, Error());
+    MOCK_METHOD1(resetCommands, void(Display));
+    MOCK_METHOD1(executeCommands, Error(Display));
     MOCK_METHOD0(getMaxVirtualDisplayCount, uint32_t());
     MOCK_METHOD4(createVirtualDisplay, Error(uint32_t, uint32_t, PixelFormat*, Display*));
     MOCK_METHOD1(destroyVirtualDisplay, Error(Display));
@@ -166,6 +166,8 @@
     MOCK_METHOD2(getPhysicalDisplayOrientation, Error(Display, AidlTransform*));
     MOCK_METHOD1(getOverlaySupport,
                  Error(aidl::android::hardware::graphics::composer3::OverlayProperties*));
+    MOCK_METHOD1(onHotplugConnect, void(Display));
+    MOCK_METHOD1(onHotplugDisconnect, void(Display));
 };
 
 } // namespace Hwc2::mock