4 files changed, 24 insertions, 4 deletions

diff --git a/src/video_core/gpu.cpp b/src/video_core/gpu.cpp
index a6f31359a3..444dc6d015 100644
--- a/src/video_core/gpu.cpp
+++ b/src/video_core/gpu.cpp
@@ -210,6 +210,10 @@ struct GPU::Impl {
         gpu_thread.Run(std::move(func), is_async);
     }
 
+    void MapInOrder(std::function<void()>&& func) {
+        gpu_thread.Run(std::move(func), is_async, true);
+    }
+
     /// Notify rasterizer that any caches of the specified region should be flushed to Switch memory
     void FlushRegion(DAddr addr, u64 size) {
         gpu_thread.FlushRegion(addr, size, is_async);
@@ -553,6 +557,10 @@ void GPU::RunInOrder(std::function<void()>&& func) {
     impl->RunInOrder(std::move(func));
 }
 
+void GPU::MapInOrder(std::function<void()>&& func) {
+    impl->MapInOrder(std::move(func));
+}
+
 void GPU::InvalidateRegion(DAddr addr, u64 size, bool preserve_gpu_writes) {
     impl->InvalidateRegion(addr, size, preserve_gpu_writes);
 }
diff --git a/src/video_core/gpu.h b/src/video_core/gpu.h
index 4afc89f0e6..d37dfa5990 100644
--- a/src/video_core/gpu.h
+++ b/src/video_core/gpu.h
@@ -257,6 +257,10 @@ public:
     /// Runs func on the GPU thread after the command lists submitted so far.
     void RunInOrder(std::function<void()>&& func);
 
+    /// RunInOrder for GPU memory maps: also done before the GPU thread reads the command lists
+    /// submitted later (with the GPU split, on its front rather than its back).
+    void MapInOrder(std::function<void()>&& func);
+
     /// Notify rasterizer that any caches of the specified region should be invalidated
     void InvalidateRegion(DAddr addr, u64 size, bool preserve_gpu_writes = false);
 
diff --git a/src/video_core/gpu_thread.cpp b/src/video_core/gpu_thread.cpp
index 55200b0647..3af8cb65a8 100644
--- a/src/video_core/gpu_thread.cpp
+++ b/src/video_core/gpu_thread.cpp
@@ -99,7 +99,12 @@ void ThreadManager::StartThread(VideoCore::RendererBase& renderer, Core::Fronten
                 } else if (std::holds_alternative<GPUTickCommand>(next.data)) {
                     split.Defer([gpu = &system.GPU()] { gpu->TickWork(); });
                 } else if (auto* run = std::get_if<RunCommand>(&next.data)) {
-                    split.DeferFunction(std::move(run->func));
+                    if (run->before_later_reads) {
+                        split.Drain();
+                        run->func();
+                    } else {
+                        split.DeferFunction(std::move(run->func));
+                    }
                 } else if (const auto* flush = std::get_if<FlushRegionCommand>(&next.data)) {
                     split.Defer([rasterizer_ptr, addr = flush->addr, size = flush->size] {
                         rasterizer_ptr->FlushRegion(addr, size);
@@ -155,8 +160,8 @@ void ThreadManager::TickGPU(bool is_async) {
     PushCommand(GPUTickCommand(), false, is_async);
 }
 
-void ThreadManager::Run(std::function<void()>&& func, bool is_async) {
-    PushCommand(RunCommand{std::move(func)}, false, is_async);
+void ThreadManager::Run(std::function<void()>&& func, bool is_async, bool before_later_reads) {
+    PushCommand(RunCommand{std::move(func), before_later_reads}, false, is_async);
 }
 
 void ThreadManager::InvalidateRegion(DAddr addr, u64 size) {
diff --git a/src/video_core/gpu_thread.h b/src/video_core/gpu_thread.h
index 796c0d89f6..927453dab0 100644
--- a/src/video_core/gpu_thread.h
+++ b/src/video_core/gpu_thread.h
@@ -80,6 +80,9 @@ struct GPUTickCommand final {};
 /// Command to run a function on the GPU thread after the commands queued before it
 struct RunCommand final {
     std::function<void()> func;
+    /// With the GPU split, run on its front (after draining the back) instead of deferring to the
+    /// back, so command lists read after this one see what func did (GMMU maps).
+    bool before_later_reads{};
 };
 
 using CommandData =
@@ -132,7 +135,7 @@ public:
     void TickGPU(bool is_async);
 
     /// Runs func on the GPU thread once the commands queued before it have been processed.
-    void Run(std::function<void()>&& func, bool is_async);
+    void Run(std::function<void()>&& func, bool is_async, bool before_later_reads = false);
 
     void NotifyShutdown();