4 files changed, 51 insertions, 0 deletions

diff --git a/src/core/core.cpp b/src/core/core.cpp
index 3532839df..3042d611b 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -140,25 +140,45 @@ struct System::Impl {
           cpu_manager{system}, reporter{system}, applet_manager{system}, time_manager{system} {}
 
     SystemResultStatus Run() {
+        std::unique_lock<std::mutex> lk(suspend_guard);
         status = SystemResultStatus::Success;
 
         kernel.Suspend(false);
         core_timing.SyncPause(false);
         cpu_manager.Pause(false);
+        is_paused = false;
 
         return status;
     }
 
     SystemResultStatus Pause() {
+        std::unique_lock<std::mutex> lk(suspend_guard);
         status = SystemResultStatus::Success;
 
         core_timing.SyncPause(true);
         kernel.Suspend(true);
         cpu_manager.Pause(true);
+        is_paused = true;
 
         return status;
     }
 
+    std::unique_lock<std::mutex> StallCPU() {
+        std::unique_lock<std::mutex> lk(suspend_guard);
+        kernel.Suspend(true);
+        core_timing.SyncPause(true);
+        cpu_manager.Pause(true);
+        return lk;
+    }
+
+    void UnstallCPU() {
+        if (!is_paused) {
+            core_timing.SyncPause(false);
+            kernel.Suspend(false);
+            cpu_manager.Pause(false);
+        }
+    }
+
     SystemResultStatus Init(System& system, Frontend::EmuWindow& emu_window) {
         LOG_DEBUG(Core, "initialized OK");
 
@@ -367,6 +387,9 @@ struct System::Impl {
         return perf_stats->GetAndResetStats(core_timing.GetGlobalTimeUs());
     }
 
+    std::mutex suspend_guard;
+    bool is_paused{};
+
     Timing::CoreTiming core_timing;
     Kernel::KernelCore kernel;
     /// RealVfsFilesystem instance
@@ -464,6 +487,14 @@ void System::Shutdown() {
     impl->Shutdown();
 }
 
+std::unique_lock<std::mutex> System::StallCPU() {
+    return impl->StallCPU();
+}
+
+void System::UnstallCPU() {
+    impl->UnstallCPU();
+}
+
 SystemResultStatus System::Load(Frontend::EmuWindow& emu_window, const std::string& filepath,
                                 u64 program_id, std::size_t program_index) {
     return impl->Load(*this, emu_window, filepath, program_id, program_index);
diff --git a/src/core/core.h b/src/core/core.h
index c1234ef77..1cfe1bba6 100644
--- a/src/core/core.h
+++ b/src/core/core.h
@@ -7,6 +7,7 @@
 #include <cstddef>
 #include <functional>
 #include <memory>
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -160,6 +161,9 @@ public:
     /// Shutdown the emulated system.
     void Shutdown();
 
+    std::unique_lock<std::mutex> StallCPU();
+    void UnstallCPU();
+
     /**
      * Load an executable application.
      * @param emu_window Reference to the host-system window used for video output and keyboard
diff --git a/src/core/hle/service/nvdrv/devices/nvhost_ctrl.cpp b/src/core/hle/service/nvdrv/devices/nvhost_ctrl.cpp
index 8b4867ca7..f9b82b504 100644
--- a/src/core/hle/service/nvdrv/devices/nvhost_ctrl.cpp
+++ b/src/core/hle/service/nvdrv/devices/nvhost_ctrl.cpp
@@ -92,6 +92,7 @@ NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector
     if (syncpoint_manager.IsSyncpointExpired(params.syncpt_id, params.threshold)) {
         params.value = syncpoint_manager.GetSyncpointMin(params.syncpt_id);
         std::memcpy(output.data(), &params, sizeof(params));
+        events_interface.failed[event_id] = false;
         return NvResult::Success;
     }
 
@@ -99,6 +100,7 @@ NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector
         syncpoint_manager.IsSyncpointExpired(params.syncpt_id, params.threshold)) {
         params.value = new_value;
         std::memcpy(output.data(), &params, sizeof(params));
+        events_interface.failed[event_id] = false;
         return NvResult::Success;
     }
 
@@ -117,6 +119,7 @@ NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector
         event.event->GetWritableEvent().Signal();
         params.value = current_syncpoint_value;
         std::memcpy(output.data(), &params, sizeof(params));
+        events_interface.failed[event_id] = false;
         return NvResult::Success;
     }
     const u32 target_value = current_syncpoint_value - diff;
@@ -146,6 +149,16 @@ NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector
     }
     params.value |= event_id;
     event.event->GetWritableEvent().Clear();
+    if (events_interface.failed[event_id]) {
+        {
+            auto lk = system.StallCPU();
+            gpu.WaitFence(params.syncpt_id, target_value);
+            system.UnstallCPU();
+        }
+        std::memcpy(output.data(), &params, sizeof(params));
+        events_interface.failed[event_id] = false;
+        return NvResult::Success;
+    }
     gpu.RegisterSyncptInterrupt(params.syncpt_id, target_value);
     std::memcpy(output.data(), &params, sizeof(params));
     return NvResult::Timeout;
@@ -201,6 +214,7 @@ NvResult nvhost_ctrl::IocCtrlClearEventWait(const std::vector<u8>& input, std::v
     if (events_interface.status[event_id] == EventState::Waiting) {
         events_interface.LiberateEvent(event_id);
     }
+    events_interface.failed[event_id] = true;
 
     syncpoint_manager.RefreshSyncpoint(events_interface.events[event_id].fence.id);
 
diff --git a/src/core/hle/service/nvdrv/nvdrv.h b/src/core/hle/service/nvdrv/nvdrv.h
index e2a1dde5b..a5af5b785 100644
--- a/src/core/hle/service/nvdrv/nvdrv.h
+++ b/src/core/hle/service/nvdrv/nvdrv.h
@@ -49,6 +49,8 @@ struct EventInterface {
     std::array<EventState, MaxNvEvents> status{};
     // Tells if an NVEvent is registered or not
     std::array<bool, MaxNvEvents> registered{};
+    // Tells the NVEvent that it has failed.
+    std::array<bool, MaxNvEvents> failed{};
     // When an NVEvent is waiting on GPU interrupt, this is the sync_point
     // associated with it.
     std::array<u32, MaxNvEvents> assigned_syncpt{};