Support multi-threading in hypervisors

Brovan/Core/Emulation/Backends/IEmulationBackend.cs

@@ -187,6 +187,8 @@ bool ReadRegisterBatch(int[] registers, ulong[] values, int count)
         /// </summary>
         bool SupportsThreadResidency => false;
 
+        int ProcessorLimit => 1;
+
         bool TryBindThread(uint threadId) => false;
 
         void UnbindThread(uint threadId)
@@ -205,6 +207,23 @@ void SelectThread(uint threadId)
         /// </summary>
         bool TryLimitSlice(int microseconds) => false;
 
+        /// <summary>
+        /// The lock the caller holds around <see cref="Emulate"/>. A backend releases it only for the time
+        /// the guest runs.
+        /// </summary>
+        void UseRunLock(object runLock)
+        {
+        }
+
+        /// <summary>Ends the slice of the thread's processor, not the thread.</summary>
+        void StopThread(uint threadId)
+        {
+        }
+
+        void StopAllProcessors()
+        {
+        }
+
         /// <summary>
         /// Answers RDTSC inside the backend from the emulator's clock. False when the backend has no such path.
         /// </summary>

Brovan/Core/Emulation/Backends/Kvm/KvmBackend.cs

@@ -111,11 +111,15 @@ public bool WriteXmmRegisters(ulong[] values)
             => Inner.TransferXmmRegisters(values, true);
 
         public bool SupportsThreadResidency => Inner.SupportsThreadResidency;
+        public int ProcessorLimit => Inner.ProcessorLimit;
         public bool TryBindThread(uint threadId) => Inner.TryBindThread(threadId);
         public void UnbindThread(uint threadId) => Inner.UnbindThread(threadId);
         public bool IsThreadResident(uint threadId) => Inner.IsThreadResident(threadId);
         public void SelectThread(uint threadId) => Inner.SelectThread(threadId);
         public bool TryLimitSlice(int microseconds) => Inner.TryLimitSlice(microseconds);
+        public void UseRunLock(object runLock) => Inner.UseRunLock(runLock);
+        public void StopThread(uint threadId) => Inner.StopThread(threadId);
+        public void StopAllProcessors() => Inner.StopAllProcessors();
         public uint ReadRegister32(Registers register)
             => Inner.ReadRegister32(register);
         public uint ReadRegister32(int register)

Brovan/Core/Emulation/Backends/Whp/WhpBackend.cs

@@ -129,11 +129,15 @@ public bool WriteXmmRegisters(ulong[] values)
             => Inner.TransferXmmRegisters(values, true);
 
         public bool SupportsThreadResidency => Inner.SupportsThreadResidency;
+        public int ProcessorLimit => Inner.ProcessorLimit;
         public bool TryBindThread(uint threadId) => Inner.TryBindThread(threadId);
         public void UnbindThread(uint threadId) => Inner.UnbindThread(threadId);
         public bool IsThreadResident(uint threadId) => Inner.IsThreadResident(threadId);
         public void SelectThread(uint threadId) => Inner.SelectThread(threadId);
         public bool TryLimitSlice(int microseconds) => Inner.TryLimitSlice(microseconds);
+        public void UseRunLock(object runLock) => Inner.UseRunLock(runLock);
+        public void StopThread(uint threadId) => Inner.StopThread(threadId);
+        public void StopAllProcessors() => Inner.StopAllProcessors();
 
         public IntPtr AddCodeHook(ulong begin, ulong end, CodeHookCallback callback)
             => Inner.AddCodeHook(begin, end, callback);