NvHost: Remake Ctrl Implementation.

src/core/hle/service/nvdrv/devices/nvhost_ctrl.cpp

@@ -1,11 +1,14 @@
-// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021 yuzu emulator team and Skyline Team and Contributors
+// (https://github.com/skyline-emu/)
+// SPDX-License-Identifier: GPL-3.0-or-later Licensed under GPLv3
+// or any later version Refer to the license.txt file included.
 
 #include <cstdlib>
 #include <cstring>
 
 #include "common/assert.h"
 #include "common/logging/log.h"
+#include "common/scope_exit.h"
 #include "core/core.h"
 #include "core/hle/kernel/k_event.h"
 #include "core/hle/kernel/k_writable_event.h"
@@ -30,9 +33,9 @@ NvResult nvhost_ctrl::Ioctl1(DeviceFD fd, Ioctl command, const std::vector<u8>&
         case 0x1c:
             return IocCtrlClearEventWait(input, output);
         case 0x1d:
-            return IocCtrlEventWait(input, output, false);
-        case 0x1e:
             return IocCtrlEventWait(input, output, true);
+        case 0x1e:
+            return IocCtrlEventWait(input, output, false);
         case 0x1f:
             return IocCtrlEventRegister(input, output);
         case 0x20:
@@ -71,54 +74,65 @@ NvResult nvhost_ctrl::NvOsGetConfigU32(const std::vector<u8>& input, std::vector
 }
 
 NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector<u8>& output,
-                                       bool is_async) {
+                                       bool is_allocation) {
     IocCtrlEventWaitParams params{};
     std::memcpy(&params, input.data(), sizeof(params));
-    LOG_DEBUG(Service_NVDRV, "syncpt_id={}, threshold={}, timeout={}, is_async={}",
-              params.syncpt_id, params.threshold, params.timeout, is_async);
+    LOG_DEBUG(Service_NVDRV, "syncpt_id={}, threshold={}, timeout={}, is_allocation={}",
+              params.fence.id, params.fence.value, params.timeout, is_allocation);
 
-    if (params.syncpt_id >= MaxSyncPoints) {
-        return NvResult::BadParameter;
-    }
-
-    u32 event_id = params.value & 0x00FF;
-
-    if (event_id >= MaxNvEvents) {
-        std::memcpy(output.data(), &params, sizeof(params));
-        return NvResult::BadParameter;
-    }
-
-    if (syncpoint_manager.IsSyncpointExpired(params.syncpt_id, params.threshold)) {
-        params.value = syncpoint_manager.GetSyncpointMin(params.syncpt_id);
+    bool must_unmark_fail = !is_allocation;
+    const u32 event_id = params.value.raw;
+    SCOPE_EXIT({
         std::memcpy(output.data(), &params, sizeof(params));
+        if (must_unmark_fail) {
             events_interface.fails[event_id] = 0;
+        }
+    });
+
+    const u32 fence_id = static_cast<u32>(params.fence.id);
+
+    if (fence_id >= MaxSyncPoints) {
+        return NvResult::BadParameter;
+    }
+
+    if (params.fence.value == 0) {
+        params.value.raw = syncpoint_manager.GetSyncpointMin(fence_id);
         return NvResult::Success;
     }
 
-    if (const auto new_value = syncpoint_manager.RefreshSyncpoint(params.syncpt_id);
-        syncpoint_manager.IsSyncpointExpired(params.syncpt_id, params.threshold)) {
-        params.value = new_value;
-        std::memcpy(output.data(), &params, sizeof(params));
-        events_interface.fails[event_id] = 0;
+    if (syncpoint_manager.IsSyncpointExpired(fence_id, params.fence.value)) {
+        params.value.raw = syncpoint_manager.GetSyncpointMin(fence_id);
+        return NvResult::Success;
+    }
+
+    if (const auto new_value = syncpoint_manager.RefreshSyncpoint(fence_id);
+        syncpoint_manager.IsSyncpointExpired(fence_id, params.fence.value)) {
+        params.value.raw = new_value;
         return NvResult::Success;
     }
 
     auto& gpu = system.GPU();
-    const u32 target_value = syncpoint_manager.GetSyncpointMax(params.syncpt_id);
+    const u32 target_value = params.fence.value;
 
-    if (!is_async) {
-        params.value = 0;
+    auto lock = events_interface.Lock();
+
+    u32 slot = [&]() {
+        if (is_allocation) {
+            params.value.raw = 0;
+            return events_interface.FindFreeEvent(fence_id);
+        } else {
+            return params.value.raw;
         }
+    }();
 
     const auto check_failing = [&]() {
-        if (events_interface.fails[event_id] > 1) {
+        if (events_interface.fails[slot] > 1) {
             {
                 auto lk = system.StallProcesses();
-                gpu.WaitFence(params.syncpt_id, target_value);
+                gpu.WaitFence(fence_id, target_value);
                 system.UnstallProcesses();
             }
-            std::memcpy(output.data(), &params, sizeof(params));
-            events_interface.fails[event_id] = 0;
+            params.value.raw = target_value;
             return true;
         }
         return false;
@@ -131,47 +145,76 @@ NvResult nvhost_ctrl::IocCtrlEventWait(const std::vector<u8>& input, std::vector
         return NvResult::Timeout;
     }
 
-    EventState status = events_interface.status[event_id];
-    const bool bad_parameter = status == EventState::Busy;
-    if (bad_parameter) {
-        std::memcpy(output.data(), &params, sizeof(params));
+    if (slot >= MaxNvEvents) {
         return NvResult::BadParameter;
     }
-    events_interface.SetEventStatus(event_id, EventState::Waiting);
-    events_interface.assigned_syncpt[event_id] = params.syncpt_id;
-    events_interface.assigned_value[event_id] = target_value;
-    if (is_async) {
-        params.value = params.syncpt_id << 4;
-    } else {
-        params.value = ((params.syncpt_id & 0xfff) << 16) | 0x10000000;
+
+    auto* event = events_interface.events[slot];
+
+    if (!event) {
+        return NvResult::BadParameter;
     }
-    params.value |= event_id;
+
+    if (events_interface.IsBeingUsed(slot)) {
+        return NvResult::BadParameter;
+    }
+
     if (check_failing()) {
         return NvResult::Success;
     }
-    gpu.RegisterSyncptInterrupt(params.syncpt_id, target_value);
-    std::memcpy(output.data(), &params, sizeof(params));
+
+    params.value.raw = 0;
+
+    events_interface.status[slot].store(EventState::Waiting, std::memory_order_release);
+    events_interface.assigned_syncpt[slot] = fence_id;
+    events_interface.assigned_value[slot] = target_value;
+    if (is_allocation) {
+        params.value.syncpoint_id_for_allocation.Assign(static_cast<u16>(fence_id));
+        params.value.event_allocated.Assign(1);
+    } else {
+        params.value.syncpoint_id.Assign(fence_id);
+    }
+    params.value.raw |= slot;
+
+    gpu.RegisterSyncptInterrupt(fence_id, target_value);
     return NvResult::Timeout;
 }
 
+NvResult nvhost_ctrl::FreeEvent(u32 slot) {
+    if (slot >= MaxNvEvents) {
+        return NvResult::BadParameter;
+    }
+
+    if (!events_interface.registered[slot]) {
+        return NvResult::Success;
+    }
+
+    if (events_interface.IsBeingUsed(slot)) {
+        return NvResult::Busy;
+    }
+
+    events_interface.Free(slot);
+    return NvResult::Success;
+}
+
 NvResult nvhost_ctrl::IocCtrlEventRegister(const std::vector<u8>& input, std::vector<u8>& output) {
     IocCtrlEventRegisterParams params{};
     std::memcpy(&params, input.data(), sizeof(params));
-    const u32 event_id = params.user_event_id & 0x00FF;
+    const u32 event_id = params.user_event_id;
     LOG_DEBUG(Service_NVDRV, " called, user_event_id: {:X}", event_id);
     if (event_id >= MaxNvEvents) {
         return NvResult::BadParameter;
     }
+
+    auto lock = events_interface.Lock();
+
     if (events_interface.registered[event_id]) {
-        const auto event_state = events_interface.status[event_id];
-        if (event_state != EventState::Free) {
-            LOG_WARNING(Service_NVDRV, "Event already registered! Unregistering previous event");
-            events_interface.UnregisterEvent(event_id);
-        } else {
-            return NvResult::BadParameter;
+        const auto result = FreeEvent(event_id);
+        if (result != NvResult::Success) {
+            return result;
         }
     }
-    events_interface.RegisterEvent(event_id);
+    events_interface.Create(event_id);
     return NvResult::Success;
 }
 
@@ -181,32 +224,33 @@ NvResult nvhost_ctrl::IocCtrlEventUnregister(const std::vector<u8>& input,
     std::memcpy(&params, input.data(), sizeof(params));
     const u32 event_id = params.user_event_id & 0x00FF;
     LOG_DEBUG(Service_NVDRV, " called, user_event_id: {:X}", event_id);
-    if (event_id >= MaxNvEvents) {
-        return NvResult::BadParameter;
-    }
-    if (!events_interface.registered[event_id]) {
-        return NvResult::BadParameter;
-    }
-    events_interface.UnregisterEvent(event_id);
-    return NvResult::Success;
+
+    auto lock = events_interface.Lock();
+    return FreeEvent(event_id);
 }
 
 NvResult nvhost_ctrl::IocCtrlClearEventWait(const std::vector<u8>& input, std::vector<u8>& output) {
-    IocCtrlEventSignalParams params{};
+    IocCtrlEventClearParams params{};
     std::memcpy(&params, input.data(), sizeof(params));
 
-    u32 event_id = params.event_id & 0x00FF;
-    LOG_WARNING(Service_NVDRV, "cleared event wait on, event_id: {:X}", event_id);
+    u32 event_id = params.event_id.slot;
+    LOG_DEBUG(Service_NVDRV, "called, event_id: {:X}", event_id);
 
     if (event_id >= MaxNvEvents) {
         return NvResult::BadParameter;
     }
-    if (events_interface.status[event_id] == EventState::Waiting) {
-        events_interface.LiberateEvent(event_id);
+
+    auto lock = events_interface.Lock();
+
+    if (events_interface.status[event_id].exchange(
+            EventState::Cancelling, std::memory_order_acq_rel) == EventState::Waiting) {
+        system.GPU().CancelSyncptInterrupt(events_interface.assigned_syncpt[event_id],
+                                           events_interface.assigned_value[event_id]);
+        syncpoint_manager.RefreshSyncpoint(events_interface.assigned_syncpt[event_id]);
     }
     events_interface.fails[event_id]++;
-
-    syncpoint_manager.RefreshSyncpoint(events_interface.events[event_id].fence.id);
+    events_interface.status[event_id].store(EventState::Cancelled, std::memory_order_release);
+    events_interface.events[event_id]->GetWritableEvent().Clear();
 
     return NvResult::Success;
 }

src/core/hle/service/nvdrv/devices/nvhost_ctrl.h

@@ -5,6 +5,7 @@
 
 #include <array>
 #include <vector>
+#include "common/bit_field.h"
 #include "common/common_types.h"
 #include "core/hle/service/nvdrv/devices/nvdevice.h"
 #include "core/hle/service/nvdrv/nvdrv.h"
@@ -27,6 +28,24 @@ public:
     void OnOpen(DeviceFD fd) override;
     void OnClose(DeviceFD fd) override;
 
+    union SyncpointEventValue {
+        u32 raw;
+
+        union {
+            BitField<0, 4, u32> partial_slot;
+            BitField<4, 28, u32> syncpoint_id;
+        };
+
+        struct {
+            u16 slot;
+            union {
+                BitField<0, 12, u16> syncpoint_id_for_allocation;
+                BitField<12, 1, u16> event_allocated;
+            };
+        };
+    };
+    static_assert(sizeof(SyncpointEventValue) == sizeof(u32));
+
 private:
     struct IocSyncptReadParams {
         u32_le id{};
@@ -83,27 +102,18 @@ private:
     };
     static_assert(sizeof(IocGetConfigParams) == 387, "IocGetConfigParams is incorrect size");
 
-    struct IocCtrlEventSignalParams {
-        u32_le event_id{};
+    struct IocCtrlEventClearParams {
+        SyncpointEventValue event_id{};
     };
-    static_assert(sizeof(IocCtrlEventSignalParams) == 4,
-                  "IocCtrlEventSignalParams is incorrect size");
+    static_assert(sizeof(IocCtrlEventClearParams) == 4,
+                  "IocCtrlEventClearParams is incorrect size");
 
     struct IocCtrlEventWaitParams {
-        u32_le syncpt_id{};
-        u32_le threshold{};
-        s32_le timeout{};
-        u32_le value{};
-    };
-    static_assert(sizeof(IocCtrlEventWaitParams) == 16, "IocCtrlEventWaitParams is incorrect size");
-
-    struct IocCtrlEventWaitAsyncParams {
-        u32_le syncpt_id{};
-        u32_le threshold{};
+        NvFence fence{};
         u32_le timeout{};
-        u32_le value{};
+        SyncpointEventValue value{};
     };
-    static_assert(sizeof(IocCtrlEventWaitAsyncParams) == 16,
+    static_assert(sizeof(IocCtrlEventWaitParams) == 16,
                   "IocCtrlEventWaitAsyncParams is incorrect size");
 
     struct IocCtrlEventRegisterParams {
@@ -124,11 +134,14 @@ private:
     static_assert(sizeof(IocCtrlEventKill) == 8, "IocCtrlEventKill is incorrect size");
 
     NvResult NvOsGetConfigU32(const std::vector<u8>& input, std::vector<u8>& output);
-    NvResult IocCtrlEventWait(const std::vector<u8>& input, std::vector<u8>& output, bool is_async);
+    NvResult IocCtrlEventWait(const std::vector<u8>& input, std::vector<u8>& output,
+                              bool is_allocation);
     NvResult IocCtrlEventRegister(const std::vector<u8>& input, std::vector<u8>& output);
     NvResult IocCtrlEventUnregister(const std::vector<u8>& input, std::vector<u8>& output);
     NvResult IocCtrlClearEventWait(const std::vector<u8>& input, std::vector<u8>& output);
 
+    NvResult FreeEvent(u32 slot);
+
     EventInterface& events_interface;
     SyncpointManager& syncpoint_manager;
 };

src/core/hle/service/nvdrv/nvdata.h

@@ -1,5 +1,7 @@
-// SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021 yuzu emulator team and Skyline Team and Contributors
+// (https://github.com/skyline-emu/)
+// SPDX-License-Identifier: GPL-3.0-or-later Licensed under GPLv3
+// or any later version Refer to the license.txt file included.
 
 #pragma once
 
@@ -78,11 +80,15 @@ enum class NvResult : u32 {
     ModuleNotPresent = 0xA000E,
 };
 
+// obtained from
+// https://github.com/skyline-emu/skyline/blob/nvdec-dev/app/src/main/cpp/skyline/services/nvdrv/devices/nvhost/ctrl.h#L47
 enum class EventState {
-    Free = 0,
-    Registered = 1,
-    Waiting = 2,
-    Busy = 3,
+    Available = 0,
+    Waiting = 1,
+    Cancelling = 2,
+    Signalling = 3,
+    Signalled = 4,
+    Cancelled = 5,
 };
 
 union Ioctl {

src/core/hle/service/nvdrv/nvdrv.cpp

@@ -1,6 +1,9 @@
-// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021 yuzu emulator team and Skyline Team and Contributors
+// (https://github.com/skyline-emu/)
+// SPDX-License-Identifier: GPL-3.0-or-later Licensed under GPLv3
+// or any later version Refer to the license.txt file included.
 
+#include <bit>
 #include <utility>
 
 #include <fmt/format.h>
@@ -26,6 +29,73 @@
 
 namespace Service::Nvidia {
 
+std::unique_lock<std::mutex> EventInterface::Lock() {
+    return std::unique_lock<std::mutex>(events_mutex);
+}
+
+void EventInterface::Signal(u32 event_id) {
+    if (status[event_id].exchange(EventState::Signalling, std::memory_order_acq_rel) ==
+        EventState::Waiting) {
+        events[event_id]->GetWritableEvent().Signal();
+    }
+    status[event_id].store(EventState::Signalled, std::memory_order_release);
+}
+
+void EventInterface::Create(u32 event_id) {
+    ASSERT(!events[event_id]);
+    ASSERT(!registered[event_id]);
+    ASSERT(!IsBeingUsed(event_id));
+    events[event_id] = backup[event_id];
+    status[event_id] = EventState::Available;
+    registered[event_id] = true;
+    const u64 mask = 1ULL << event_id;
+    fails[event_id] = 0;
+    events_mask |= mask;
+    LOG_CRITICAL(Service_NVDRV, "Created Event {}", event_id);
+}
+
+void EventInterface::Free(u32 event_id) {
+    ASSERT(events[event_id]);
+    ASSERT(registered[event_id]);
+    ASSERT(!IsBeingUsed(event_id));
+
+    backup[event_id]->GetWritableEvent().Clear();
+    events[event_id] = nullptr;
+    status[event_id] = EventState::Available;
+    registered[event_id] = false;
+    const u64 mask = ~(1ULL << event_id);
+    events_mask &= mask;
+    LOG_CRITICAL(Service_NVDRV, "Freed Event {}", event_id);
+}
+
+u32 EventInterface::FindFreeEvent(u32 syncpoint_id) {
+    u32 slot{MaxNvEvents};
+    u32 free_slot{MaxNvEvents};
+    for (u32 i = 0; i < MaxNvEvents; i++) {
+        if (registered[i]) {
+            if (!IsBeingUsed(i)) {
+                slot = i;
+                if (assigned_syncpt[i] == syncpoint_id) {
+                    return slot;
+                }
+            }
+        } else if (free_slot == MaxNvEvents) {
+            free_slot = i;
+        }
+    }
+    if (free_slot < MaxNvEvents) {
+        Create(free_slot);
+        return free_slot;
+    }
+
+    if (slot < MaxNvEvents) {
+        return slot;
+    }
+
+    LOG_CRITICAL(Service_NVDRV, "Failed to allocate an event");
+    return 0;
+}
+
 void InstallInterfaces(SM::ServiceManager& service_manager, NVFlinger::NVFlinger& nvflinger,
                        Core::System& system) {
     auto module_ = std::make_shared<Module>(system);
@@ -38,12 +108,14 @@ void InstallInterfaces(SM::ServiceManager& service_manager, NVFlinger::NVFlinger
 }
 
 Module::Module(Core::System& system)
-    : syncpoint_manager{system.GPU()}, service_context{system, "nvdrv"} {
+    : syncpoint_manager{system.GPU()}, events_interface{*this}, service_context{system, "nvdrv"} {
+    events_interface.events_mask = 0;
     for (u32 i = 0; i < MaxNvEvents; i++) {
-        events_interface.events[i].event =
-            service_context.CreateEvent(fmt::format("NVDRV::NvEvent_{}", i));
-        events_interface.status[i] = EventState::Free;
+        events_interface.status[i] = EventState::Available;
+        events_interface.events[i] = nullptr;
         events_interface.registered[i] = false;
+        events_interface.backup[i] =
+            service_context.CreateEvent(fmt::format("NVDRV::NvEvent_{}", i));
     }
     auto nvmap_dev = std::make_shared<Devices::nvmap>(system);
     devices["/dev/nvhost-as-gpu"] = std::make_shared<Devices::nvhost_as_gpu>(system, nvmap_dev);
@@ -62,8 +134,12 @@ Module::Module(Core::System& system)
 }
 
 Module::~Module() {
+    auto lock = events_interface.Lock();
     for (u32 i = 0; i < MaxNvEvents; i++) {
-        service_context.CloseEvent(events_interface.events[i].event);
+        if (events_interface.registered[i]) {
+            events_interface.Free(i);
+        }
+        service_context.CloseEvent(events_interface.backup[i]);
     }
 }
 
@@ -169,21 +245,41 @@ NvResult Module::Close(DeviceFD fd) {
 }
 
 void Module::SignalSyncpt(const u32 syncpoint_id, const u32 value) {
-    for (u32 i = 0; i < MaxNvEvents; i++) {
-        if (events_interface.assigned_syncpt[i] == syncpoint_id &&
+    const u32 max = MaxNvEvents - std::countl_zero(events_interface.events_mask);
+    const u32 min = std::countr_zero(events_interface.events_mask);
+    for (u32 i = min; i < max; i++) {
+        if (events_interface.registered[i] && events_interface.assigned_syncpt[i] == syncpoint_id &&
             events_interface.assigned_value[i] == value) {
-            events_interface.LiberateEvent(i);
-            events_interface.events[i].event->GetWritableEvent().Signal();
+            events_interface.Signal(i);
         }
     }
 }
 
-Kernel::KReadableEvent& Module::GetEvent(const u32 event_id) {
-    return events_interface.events[event_id].event->GetReadableEvent();
+Kernel::KEvent* Module::GetEvent(u32 event_id) {
+    const auto event = Devices::nvhost_ctrl::SyncpointEventValue{.raw = event_id};
+
+    const bool allocated = event.event_allocated.Value() != 0;
+    const u32 slot{allocated ? event.partial_slot.Value() : static_cast<u32>(event.slot)};
+    if (slot >= MaxNvEvents) {
+        ASSERT(false);
+        return nullptr;
     }
 
-Kernel::KWritableEvent& Module::GetEventWriteable(const u32 event_id) {
-    return events_interface.events[event_id].event->GetWritableEvent();
+    const u32 syncpoint_id{allocated ? event.syncpoint_id_for_allocation.Value()
+                                     : event.syncpoint_id.Value()};
+
+    auto lock = events_interface.Lock();
+
+    if (events_interface.registered[slot] &&
+        events_interface.assigned_syncpt[slot] == syncpoint_id) {
+        ASSERT(events_interface.events[slot]);
+        return events_interface.events[slot];
+    }
+    // Temporary hack.
+    events_interface.Create(slot);
+    events_interface.assigned_syncpt[slot] = syncpoint_id;
+    ASSERT(false);
+    return events_interface.events[slot];
 }
 
 } // namespace Service::Nvidia

src/core/hle/service/nvdrv/nvdrv.h

@@ -1,5 +1,7 @@
-// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021 yuzu emulator team and Skyline Team and Contributors
+// (https://github.com/skyline-emu/)
+// SPDX-License-Identifier: GPL-3.0-or-later Licensed under GPLv3
+// or any later version Refer to the license.txt file included.
 
 #pragma once
 
@@ -34,19 +36,20 @@ namespace Devices {
 class nvdevice;
 }
 
-/// Represents an Nvidia event
-struct NvEvent {
-    Kernel::KEvent* event{};
-    NvFence fence{};
-};
+class Module;
 
-struct EventInterface {
-    // Mask representing currently busy events
+class EventInterface {
+public:
+    EventInterface(Module& module_) : module{module_} {}
+
+    // Mask representing registered events
     u64 events_mask{};
     // Each kernel event associated to an NV event
-    std::array<NvEvent, MaxNvEvents> events;
+    std::array<Kernel::KEvent*, MaxNvEvents> events{};
+    // Backup NV event
+    std::array<Kernel::KEvent*, MaxNvEvents> backup{};
     // The status of the current NVEvent
-    std::array<EventState, MaxNvEvents> status{};
+    std::array<std::atomic<EventState>, MaxNvEvents> status{};
     // Tells if an NVEvent is registered or not
     std::array<bool, MaxNvEvents> registered{};
     // Tells the NVEvent that it has failed.
@@ -59,50 +62,26 @@ struct EventInterface {
     std::array<u32, MaxNvEvents> assigned_value{};
     // Constant to denote an unasigned syncpoint.
     static constexpr u32 unassigned_syncpt = 0xFFFFFFFF;
-    std::optional<u32> GetFreeEvent() const {
-        u64 mask = events_mask;
-        for (u32 i = 0; i < MaxNvEvents; i++) {
-            const bool is_free = (mask & 0x1) == 0;
-            if (is_free) {
-                if (status[i] == EventState::Registered || status[i] == EventState::Free) {
-                    return {i};
-                }
-            }
-            mask = mask >> 1;
-        }
-        return std::nullopt;
-    }
-    void SetEventStatus(const u32 event_id, EventState new_status) {
-        EventState old_status = status[event_id];
-        if (old_status == new_status) {
-            return;
-        }
-        status[event_id] = new_status;
-        if (new_status == EventState::Registered) {
-            registered[event_id] = true;
-        }
-        if (new_status == EventState::Waiting || new_status == EventState::Busy) {
-            events_mask |= (1ULL << event_id);
-        }
-    }
-    void RegisterEvent(const u32 event_id) {
-        registered[event_id] = true;
-        if (status[event_id] == EventState::Free) {
-            status[event_id] = EventState::Registered;
-        }
-    }
-    void UnregisterEvent(const u32 event_id) {
-        registered[event_id] = false;
-        if (status[event_id] == EventState::Registered) {
-            status[event_id] = EventState::Free;
-        }
-    }
-    void LiberateEvent(const u32 event_id) {
-        status[event_id] = registered[event_id] ? EventState::Registered : EventState::Free;
-        events_mask &= ~(1ULL << event_id);
-        assigned_syncpt[event_id] = unassigned_syncpt;
-        assigned_value[event_id] = 0;
+
+    bool IsBeingUsed(u32 event_id) {
+        const auto current_status = status[event_id].load(std::memory_order_acquire);
+        return current_status == EventState::Waiting || current_status == EventState::Cancelling ||
+               current_status == EventState::Signalling;
     }
+
+    std::unique_lock<std::mutex> Lock();
+
+    void Signal(u32 event_id);
+
+    void Create(u32 event_id);
+
+    void Free(u32 event_id);
+
+    u32 FindFreeEvent(u32 syncpoint_id);
+
+private:
+    std::mutex events_mutex;
+    Module& module;
 };
 
 class Module final {
@@ -139,11 +118,11 @@ public:
 
     void SignalSyncpt(const u32 syncpoint_id, const u32 value);
 
-    Kernel::KReadableEvent& GetEvent(u32 event_id);
-
-    Kernel::KWritableEvent& GetEventWriteable(u32 event_id);
+    Kernel::KEvent* GetEvent(u32 event_id);
 
 private:
+    friend class EventInterface;
+
     /// Manages syncpoints on the host
     SyncpointManager syncpoint_manager;
 
@@ -159,6 +138,9 @@ private:
     EventInterface events_interface;
 
     KernelHelpers::ServiceContext service_context;
+
+    void CreateEvent(u32 event_id);
+    void FreeEvent(u32 event_id);
 };
 
 /// Registers all NVDRV services with the specified service manager.

src/core/hle/service/nvdrv/nvdrv_interface.cpp

@@ -5,6 +5,7 @@
 #include "common/logging/log.h"
 #include "core/core.h"
 #include "core/hle/ipc_helpers.h"
+#include "core/hle/kernel/k_event.h"
 #include "core/hle/kernel/k_readable_event.h"
 #include "core/hle/service/nvdrv/nvdata.h"
 #include "core/hle/service/nvdrv/nvdrv.h"
@@ -164,8 +165,7 @@ void NVDRV::Initialize(Kernel::HLERequestContext& ctx) {
 void NVDRV::QueryEvent(Kernel::HLERequestContext& ctx) {
     IPC::RequestParser rp{ctx};
     const auto fd = rp.Pop<DeviceFD>();
-    const auto event_id = rp.Pop<u32>() & 0x00FF;
-    LOG_WARNING(Service_NVDRV, "(STUBBED) called, fd={:X}, event_id={:X}", fd, event_id);
+    const auto event_id = rp.Pop<u32>();
 
     if (!is_initialized) {
         ServiceError(ctx, NvResult::NotInitialized);
@@ -180,12 +180,13 @@ void NVDRV::QueryEvent(Kernel::HLERequestContext& ctx) {
         return;
     }
 
-    if (event_id < MaxNvEvents) {
+    auto* event = nvdrv->GetEvent(event_id);
+
+    if (event) {
         IPC::ResponseBuilder rb{ctx, 3, 1};
         rb.Push(ResultSuccess);
-        auto& event = nvdrv->GetEvent(event_id);
-        event.Clear();
-        rb.PushCopyObjects(event);
+        auto& readable_event = event->GetReadableEvent();
+        rb.PushCopyObjects(readable_event);
         rb.PushEnum(NvResult::Success);
     } else {
         IPC::ResponseBuilder rb{ctx, 3};

src/video_core/gpu.h

@@ -201,7 +201,7 @@ public:
 
     void RegisterSyncptInterrupt(u32 syncpoint_id, u32 value);
 
-    [[nodiscard]] bool CancelSyncptInterrupt(u32 syncpoint_id, u32 value);
+    bool CancelSyncptInterrupt(u32 syncpoint_id, u32 value);
 
     [[nodiscard]] u64 GetTicks() const;