[idd] transport: arbitrate interaction requests

idd/LGCommon/PipeMsg.h

@@ -52,8 +52,8 @@ struct LGPipeMsg
   {
     struct
     {
-      uint32_t x;
-      uint32_t y;
+      int32_t x;
+      int32_t y;
     }
     curorPos;
 

idd/LGIdd/display/CDeviceContext.cpp

@@ -444,7 +444,8 @@ void CDeviceContext::OnSwapChainReady()
 
 // Display configuration
 
-void CDeviceContext::SetResolution(uint32_t width, uint32_t height)
+InteractionResult CDeviceContext::SetResolution(
+  uint32_t width, uint32_t height)
 {
   const CDisplayConfiguration::ResolutionResult result =
     m_displayConfiguration.SetResolution(
@@ -457,18 +458,21 @@ void CDeviceContext::SetResolution(uint32_t width, uint32_t height)
       // IddCxMonitorUpdateModes[2] does not invalidate Windows' cached mode
       // list, so depart and re-arrive the monitor to rebuild the topology.
       ReplugMonitor();
-      break;
+      return InteractionResult::ACCEPTED;
 
     case CDisplayConfiguration::ResolutionStatus::TOO_LARGE:
       g_pipe.ResolutionRejected(width, height, result.requiredMiB);
-      break;
+      return InteractionResult::REJECTED;
 
     case CDisplayConfiguration::ResolutionStatus::UNSUPPORTED:
       g_pipe.ResolutionRejected(width, height, 0);
-      break;
+      return InteractionResult::REJECTED;
+
+    case CDisplayConfiguration::ResolutionStatus::INVALID:
+      return InteractionResult::REJECTED;
 
     default:
-      break;
+      return InteractionResult::FAILED;
   }
 }
 
@@ -620,18 +624,19 @@ void CDeviceContext::TransportTimer()
   m_transport->Process(*this);
 }
 
-void CDeviceContext::OnSetCursorPos(
+InteractionResult CDeviceContext::OnSetCursorPos(
   const SourceKey& source, int32_t x, int32_t y)
 {
   UNREFERENCED_PARAMETER(source);
-  g_pipe.SetCursorPos(x, y);
+  return g_pipe.SetCursorPos(x, y) ?
+    InteractionResult::ACCEPTED : InteractionResult::UNAVAILABLE;
 }
 
-void CDeviceContext::OnSetResolution(const SourceKey& source,
+InteractionResult CDeviceContext::OnSetResolution(const SourceKey& source,
   uint32_t width, uint32_t height)
 {
   UNREFERENCED_PARAMETER(source);
-  SetResolution(width, height);
+  return SetResolution(width, height);
 }
 
 void CDeviceContext::OnRecoveryRequest(const SourceKey& source,

idd/LGIdd/display/CDeviceContext.h

@@ -74,13 +74,13 @@ private:
 
   bool InitializeTransport();
   void TransportTimer();
-  void OnSetCursorPos(
+  InteractionResult OnSetCursorPos(
     const SourceKey& source, int32_t x, int32_t y) override;
-  void OnSetResolution(const SourceKey& source,
+  InteractionResult OnSetResolution(const SourceKey& source,
     uint32_t width, uint32_t height) override;
   void OnRecoveryRequest(const SourceKey& source,
     uint64_t session, uint32_t serial, bool active) override;
-  void SetResolution(uint32_t width, uint32_t height);
+  InteractionResult SetResolution(uint32_t width, uint32_t height);
 
 public:
   explicit CDeviceContext(_In_ WDFDEVICE wdfDevice);

idd/LGIdd/ipc/CPipeServer.cpp

@@ -171,11 +171,11 @@ void CPipeServer::ClearRecoveryHandler(void * opaque)
   m_recoveryOpaque  = nullptr;
 }
 
-void CPipeServer::SetCursorPos(uint32_t x, uint32_t y)
+bool CPipeServer::SetCursorPos(int32_t x, int32_t y)
 {
   // do not send cursor messages if we are not connected or they will end up queued
   if (!m_endpoint.IsConnected())
-    return;
+    return false;
 
   LGPipeMsg msg = {};
   msg.size       = sizeof(msg);
@@ -184,7 +184,7 @@ void CPipeServer::SetCursorPos(uint32_t x, uint32_t y)
   msg.curorPos.y = y;
   // Cursor position is transient. If the connection is lost during this
   // write, drop it instead of replaying stale coordinates after reconnect.
-  m_endpoint.Send(&msg, sizeof(msg));
+  return m_endpoint.Send(&msg, sizeof(msg));
 }
 
 void CPipeServer::SetDisplayMode(

idd/LGIdd/ipc/CPipeServer.h

@@ -72,7 +72,7 @@ class CPipeServer : private IPipeEndpointHandler
     void SetRecoveryHandler(RecoveryHandler handler, void * opaque);
     void ClearRecoveryHandler(void * opaque);
 
-    void SetCursorPos(uint32_t x, uint32_t y);
+    bool SetCursorPos(int32_t x, int32_t y);
     void SetDisplayMode(
       uint32_t width, uint32_t height, uint32_t refreshMilliHz);
     void SetGPUStatus(bool software);

idd/LGIdd/transport/CInputHub.cpp

@@ -28,6 +28,12 @@ static bool SameSource(const SourceKey& left, const SourceKey& right)
     left.client == right.client && left.generation == right.generation;
 }
 
+static bool SameClient(const SourceKey& left, const SourceKey& right)
+{
+  return left.backend == right.backend && left.epoch == right.epoch &&
+    left.client == right.client;
+}
+
 CInputHub::CInputHub()
 {
   for (Source& source : m_sources)
@@ -222,6 +228,12 @@ void CInputHub::Unbind(BackendId backend, uint32_t epoch)
           m_owner = {};
           m_ownerDeadline = 0;
         }
+        if (m_interactionOwner.backend == backend &&
+            m_interactionOwner.epoch == epoch)
+        {
+          ClearInteraction();
+        }
+        AdvanceInteractionSerial();
         break;
       }
   }
@@ -245,6 +257,94 @@ void CInputHub::Unbind(BackendId backend, uint32_t epoch)
   }
 }
 
+InteractionResult CInputHub::CheckInteraction(
+  SourceKey& source, InteractionPermit& permit)
+{
+  permit = {};
+  if (!source.backend || !source.epoch || !source.client)
+    return InteractionResult::STALE;
+
+  CSRWExclusiveLock lock(m_lock);
+  if (m_started && m_sink)
+    CheckState();
+
+  if (m_owner.backend)
+  {
+    if (!SameClient(m_owner, source))
+      return InteractionResult::BUSY;
+    if (source.generation && source.generation != m_owner.generation)
+      return InteractionResult::BUSY;
+    source.generation = m_owner.generation;
+    permit.serial = m_interactionSerial;
+    permit.source = source;
+    return InteractionResult::ACCEPTED;
+  }
+
+  const uint64_t now = GetTickCount64();
+  if (m_interactionOwner.backend && now >= m_interactionDeadline)
+    InvalidateInteraction();
+
+  if (!m_interactionOwner.backend)
+  {
+    permit.serial = m_interactionSerial;
+    permit.source = source;
+    return InteractionResult::ACCEPTED;
+  }
+
+  if (!SameClient(m_interactionOwner, source) ||
+      (source.generation && m_interactionOwner.generation &&
+       source.generation != m_interactionOwner.generation))
+    return InteractionResult::BUSY;
+
+  if (!source.generation)
+    source.generation = m_interactionOwner.generation;
+  permit.serial = m_interactionSerial;
+  permit.source = source;
+  return InteractionResult::ACCEPTED;
+}
+
+void CInputHub::CommitInteraction(
+  const SourceKey& source, const InteractionPermit& permit)
+{
+  if (!source.backend || !source.epoch || !source.client || !permit.serial ||
+      !SameSource(source, permit.source))
+    return;
+
+  CSRWExclusiveLock lock(m_lock);
+  if (m_started && m_sink)
+    CheckState();
+  if (permit.serial != m_interactionSerial)
+    return;
+  if (m_owner.backend)
+    return;
+
+  const uint64_t now = GetTickCount64();
+  if (m_interactionOwner.backend &&
+      (!SameClient(m_interactionOwner, source) ||
+       (source.generation && m_interactionOwner.generation &&
+        source.generation != m_interactionOwner.generation)))
+    return;
+
+  if (!m_interactionOwner.backend)
+    m_interactionOwner = source;
+  else if (!m_interactionOwner.generation)
+    m_interactionOwner.generation = source.generation;
+  m_interactionDeadline = now + INTERACTION_LEASE_MS;
+  AdvanceInteractionSerial();
+}
+
+void CInputHub::RevokeInteraction(BackendId backend, uint32_t epoch)
+{
+  if (!backend || !epoch)
+    return;
+
+  CSRWExclusiveLock lock(m_lock);
+  if (m_interactionOwner.backend == backend &&
+      m_interactionOwner.epoch == epoch)
+    ClearInteraction();
+  AdvanceInteractionSerial();
+}
+
 bool CInputHub::TakeFailure(SourceKey& source)
 {
   CSRWSharedLock lifecycleLock(m_lifecycleLock);
@@ -273,6 +373,7 @@ bool CInputHub::Start(IInputSink& sink)
     m_sink      = &sink;
     m_sinkState = sink.GetState();
     m_started   = true;
+    InvalidateInteraction();
     for (Source& source : m_sources)
       if (source.active)
       {
@@ -298,6 +399,12 @@ bool CInputHub::Start(IInputSink& sink)
           m_owner = {};
           m_ownerDeadline = 0;
         }
+        if (m_interactionOwner.backend == source.backend &&
+            m_interactionOwner.epoch == source.epoch)
+        {
+          ClearInteraction();
+        }
+        AdvanceInteractionSerial();
         source.active         = false;
         source.failed         = true;
         source.failurePending = true;
@@ -329,7 +436,10 @@ void CInputHub::Stop()
   {
     CSRWExclusiveLock lock(m_lock);
     if (!m_started)
+    {
+      InvalidateInteraction();
       return;
+    }
     m_started = false;
     for (Source& source : m_sources)
       if (source.endpoint && source.running)
@@ -341,6 +451,7 @@ void CInputHub::Stop()
     reset = m_owner.backend != 0;
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
   }
 
   for (unsigned i = count; i > 0; --i)
@@ -389,18 +500,38 @@ bool CInputHub::OwnerValid(const SourceKey& source) const
   return SourceValid(source) && SameSource(m_owner, source);
 }
 
+void CInputHub::ClearInteraction()
+{
+  m_interactionOwner    = {};
+  m_interactionDeadline = 0;
+}
+
+void CInputHub::InvalidateInteraction()
+{
+  ClearInteraction();
+  AdvanceInteractionSerial();
+}
+
+void CInputHub::AdvanceInteractionSerial()
+{
+  ++m_interactionSerial;
+  if (!m_interactionSerial)
+    ++m_interactionSerial;
+}
+
 bool CInputHub::CheckState()
 {
   if (!m_started || !m_sink)
     return false;
 
   const uint64_t state = m_sink->GetState();
-  if (state != m_sinkState || !(state & 1))
+  if (state != m_sinkState)
   {
     if (m_owner.backend)
       m_sink->Reset();
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
     m_sinkState     = state;
   }
   else if (m_owner.backend && GetTickCount64() >= m_ownerDeadline)
@@ -408,6 +539,7 @@ bool CInputHub::CheckState()
     m_sink->Reset();
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
   }
   return (state & 1) != 0;
 }
@@ -449,6 +581,12 @@ void CInputHub::Failed(Source& source)
     m_owner = {};
     m_ownerDeadline = 0;
   }
+  if (m_interactionOwner.backend == source.backend &&
+      m_interactionOwner.epoch == source.epoch)
+  {
+    ClearInteraction();
+  }
+  AdvanceInteractionSerial();
   source.active         = false;
   source.failed         = true;
   source.failurePending = true;
@@ -468,10 +606,12 @@ InputResult CInputHub::Claim(const SourceKey& source)
   {
     const uint64_t state = m_sink->GetState();
     m_sinkState = state;
+    InvalidateInteraction();
     return InputResult::UNAVAILABLE;
   }
   m_owner         = source;
   m_ownerDeadline = GetTickCount64() + OWNER_LEASE_MS;
+  InvalidateInteraction();
   return InputResult::ACCEPTED;
 }
 
@@ -500,6 +640,7 @@ InputResult CInputHub::Release(const SourceKey& source, bool reset)
     accepted = m_sink->Reset();
   m_owner         = {};
   m_ownerDeadline = 0;
+  InvalidateInteraction();
   return accepted ? InputResult::ACCEPTED : InputResult::UNAVAILABLE;
 }
 
@@ -518,6 +659,7 @@ InputResult CInputHub::SendMouseRelative(const SourceKey& source,
     m_sink->Reset();
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
     return InputResult::UNAVAILABLE;
   }
   m_ownerDeadline = GetTickCount64() + OWNER_LEASE_MS;
@@ -539,6 +681,7 @@ InputResult CInputHub::SendMouseAbsolute(const SourceKey& source,
     m_sink->Reset();
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
     return InputResult::UNAVAILABLE;
   }
   m_ownerDeadline = GetTickCount64() + OWNER_LEASE_MS;
@@ -560,6 +703,7 @@ InputResult CInputHub::SendKeyboard(const SourceKey& source,
     m_sink->Reset();
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
     return InputResult::UNAVAILABLE;
   }
   m_ownerDeadline = GetTickCount64() + OWNER_LEASE_MS;
@@ -579,6 +723,7 @@ InputResult CInputHub::Reset(const SourceKey& source)
   {
     m_owner         = {};
     m_ownerDeadline = 0;
+    InvalidateInteraction();
     return InputResult::UNAVAILABLE;
   }
   m_ownerDeadline = GetTickCount64() + OWNER_LEASE_MS;

idd/LGIdd/transport/CInputHub.h

@@ -31,9 +31,17 @@ class IInputSink;
 
 class CInputHub final : public IInputTransport
 {
+public:
+  struct InteractionPermit
+  {
+    uint64_t serial = 0;
+    SourceKey source;
+  };
+
 private:
   static constexpr unsigned MAX_SOURCES = 8;
   static constexpr uint64_t OWNER_LEASE_MS = 500;
+  static constexpr uint64_t INTERACTION_LEASE_MS = 500;
 
   struct Source final : public IInputTarget
   {
@@ -72,12 +80,18 @@ private:
   uint64_t         m_sinkState = 0;
   SourceKey        m_owner;
   uint64_t         m_ownerDeadline = 0;
+  SourceKey        m_interactionOwner;
+  uint64_t         m_interactionDeadline = 0;
+  uint64_t         m_interactionSerial = 1;
   bool             m_started = false;
 
   bool SourceValid(const SourceKey& source) const;
   bool BindingPresent(const SourceKey& source) const;
   bool BindingValid(const SourceKey& source) const;
   bool OwnerValid(const SourceKey& source) const;
+  void ClearInteraction();
+  void InvalidateInteraction();
+  void AdvanceInteractionSerial();
   bool CheckState();
   InputTargetState GetState(const SourceKey& source);
   void Failed(Source& source);
@@ -101,6 +115,11 @@ public:
 
   bool Bind(BackendId backend, uint32_t epoch, IInputSource& source);
   void Unbind(BackendId backend, uint32_t epoch);
+  InteractionResult CheckInteraction(
+    SourceKey& source, InteractionPermit& permit);
+  void CommitInteraction(
+    const SourceKey& source, const InteractionPermit& permit);
+  void RevokeInteraction(BackendId backend, uint32_t epoch);
   bool TakeFailure(SourceKey& source);
 
   bool Start(IInputSink& sink) override;

idd/LGIdd/transport/CTransportManager.cpp

@@ -34,6 +34,8 @@ class CSourceEvents final : public ITransportEvents
 private:
   BackendId         m_backend;
   uint32_t          m_epoch;
+  bool              m_interactions;
+  CInputHub&         m_input;
   ITransportEvents& m_events;
 
   SourceKey Stamp(const SourceKey& source) const
@@ -46,19 +48,45 @@ private:
 
 public:
   CSourceEvents(
-    BackendId backend, uint32_t epoch, ITransportEvents& events) :
-    m_backend(backend), m_epoch(epoch), m_events(events) {}
+    BackendId backend, uint32_t epoch, bool interactions, CInputHub& input,
+    ITransportEvents& events) :
+    m_backend(backend), m_epoch(epoch), m_interactions(interactions),
+    m_input(input), m_events(events) {}
 
-  void OnSetCursorPos(
+  InteractionResult OnSetCursorPos(
     const SourceKey& source, int32_t x, int32_t y) override
   {
-    m_events.OnSetCursorPos(Stamp(source), x, y);
+    if (!m_interactions)
+      return InteractionResult::UNAVAILABLE;
+    SourceKey stamped = Stamp(source);
+    CInputHub::InteractionPermit permit;
+    const InteractionResult result =
+      m_input.CheckInteraction(stamped, permit);
+    if (result != InteractionResult::ACCEPTED)
+      return result;
+    const InteractionResult applied =
+      m_events.OnSetCursorPos(stamped, x, y);
+    if (applied == InteractionResult::ACCEPTED)
+      m_input.CommitInteraction(stamped, permit);
+    return applied;
   }
 
-  void OnSetResolution(const SourceKey& source,
+  InteractionResult OnSetResolution(const SourceKey& source,
     uint32_t width, uint32_t height) override
   {
-    m_events.OnSetResolution(Stamp(source), width, height);
+    if (!m_interactions)
+      return InteractionResult::UNAVAILABLE;
+    SourceKey stamped = Stamp(source);
+    CInputHub::InteractionPermit permit;
+    const InteractionResult result =
+      m_input.CheckInteraction(stamped, permit);
+    if (result != InteractionResult::ACCEPTED)
+      return result;
+    const InteractionResult applied =
+      m_events.OnSetResolution(stamped, width, height);
+    if (applied == InteractionResult::ACCEPTED)
+      m_input.CommitInteraction(stamped, permit);
+    return applied;
   }
 
   void OnRecoveryRequest(const SourceKey& source,
@@ -518,6 +546,7 @@ void CTransportManager::HandleServiceFailures()
       }
 
       m_control.Remove(token.backend, token.epoch);
+      m_input.RevokeInteraction(token.backend, token.epoch);
       if (restart)
       {
         RemoveServices(entry);
@@ -622,6 +651,7 @@ void CTransportManager::RemoveServices(Entry& entry)
     entry.inputAdded     = false;
   }
 
+  m_input.RevokeInteraction(id, epoch);
   if (inputAdded)
     m_input.Unbind(id, epoch);
   if (controlAdded)
@@ -988,8 +1018,14 @@ ITransport::ProcessResult CTransportManager::Process(
     if (setup)
       SetupEntry(entry, alignment);
 
+    bool interactions = false;
+    {
+      CSRWSharedLock entryLock(entry.lock);
+      interactions = entry.controlAdded;
+    }
     DrainRecovery(entry, transport);
-    CSourceEvents sourceEvents(id, epoch, events);
+    CSourceEvents sourceEvents(
+      id, epoch, interactions, m_input, events);
     const ProcessResult result = transport->Process(sourceEvents);
     DrainRecovery(entry, transport);
     HandleProcessResult(entry, result);

idd/LGIdd/transport/ITransport.h

@@ -40,14 +40,24 @@ struct SourceKey
   uint32_t  generation = 0;
 };
 
+enum class InteractionResult
+{
+  ACCEPTED,
+  BUSY,
+  UNAVAILABLE,
+  STALE,
+  REJECTED,
+  FAILED,
+};
+
 class ITransportEvents
 {
 public:
   virtual ~ITransportEvents() = default;
 
-  virtual void OnSetCursorPos(
+  virtual InteractionResult OnSetCursorPos(
     const SourceKey& source, int32_t x, int32_t y) = 0;
-  virtual void OnSetResolution(
+  virtual InteractionResult OnSetResolution(
     const SourceKey& source, uint32_t width, uint32_t height) = 0;
   virtual void OnRecoveryRequest(const SourceKey& source,
     uint64_t session, uint32_t serial, bool active) = 0;

idd/LGIdd/transport/lgmp/CLGMPTransport.cpp

@@ -138,26 +138,43 @@ ITransport::ProcessResult CLGMPTransport::Process(ITransportEvents& events)
   while ((status = m_control.ReadDataWithSource(
       data, &size, &sourceClientID)) == LGMP_OK)
   {
+    if (size < sizeof(KVMFRMessage))
+    {
+      DEBUG_WARN("Ignoring invalid KVMFR message");
+      m_control.AckData();
+      continue;
+    }
+
     KVMFRMessage * msg = reinterpret_cast<KVMFRMessage *>(data);
     switch (msg->type)
     {
       case KVMFR_MESSAGE_SETCURSORPOS:
       {
-        SourceKey source;
-        source.client = sourceClientID;
-        KVMFRSetCursorPos * position =
-          reinterpret_cast<KVMFRSetCursorPos *>(msg);
-        events.OnSetCursorPos(source, position->x, position->y);
+        if (size == sizeof(KVMFRSetCursorPos))
+        {
+          SourceKey source;
+          source.client = sourceClientID;
+          const KVMFRSetCursorPos * position =
+            reinterpret_cast<const KVMFRSetCursorPos *>(msg);
+          events.OnSetCursorPos(source, position->x, position->y);
+        }
+        else
+          DEBUG_WARN("Ignoring invalid KVMFR cursor position");
         break;
       }
 
       case KVMFR_MESSAGE_WINDOWSIZE:
       {
-        SourceKey source;
-        source.client = sourceClientID;
-        KVMFRWindowSize * window =
-          reinterpret_cast<KVMFRWindowSize *>(msg);
-        events.OnSetResolution(source, window->w, window->h);
+        if (size == sizeof(KVMFRWindowSize))
+        {
+          SourceKey source;
+          source.client = sourceClientID;
+          const KVMFRWindowSize * window =
+            reinterpret_cast<const KVMFRWindowSize *>(msg);
+          events.OnSetResolution(source, window->w, window->h);
+        }
+        else
+          DEBUG_WARN("Ignoring invalid KVMFR window size");
         break;
       }