Extend base-hw specific vm-session (fix #738)

Introduce pause syscall for VM objects, and extend the vm-session interface
to support it.

base-hw/include/kernel/syscalls.h

@@ -80,8 +80,9 @@ namespace Kernel
 		ACK_SIGNAL = 29,
 
 		/* vm specific */
-		NEW_VM = 24,
-		RUN_VM = 25,
+		NEW_VM   = 24,
+		RUN_VM   = 25,
+		PAUSE_VM = 31,
 	};
 
 	/*****************************************************************
@@ -546,6 +547,17 @@ namespace Kernel
 	 */
 	inline void run_vm(unsigned const id) {
 		syscall(RUN_VM, (Syscall_arg)id); }
+
+
+	/**
+	 * Stop execution of a virtual-machine
+	 *
+	 * \param id  ID of the targeted VM
+	 *
+	 * Restricted to core threads.
+	 */
+	inline void pause_vm(unsigned const id) {
+		syscall(PAUSE_VM, (Syscall_arg)id); }
 }
 
 #endif /* _INCLUDE__KERNEL__SYSCALLS_H_ */

base-hw/include/vm_session/client.h

@@ -41,8 +41,8 @@ namespace Genode
 		void exception_handler(Signal_context_capability handler) {
 			call<Rpc_exception_handler>(handler); }
 
-		void run() {
-			call<Rpc_run>(); }
+		void run()   { call<Rpc_run>();   }
+		void pause() { call<Rpc_pause>(); }
 	};
 }
 

base-hw/include/vm_session/vm_session.h

@@ -46,6 +46,12 @@ namespace Genode {
 			 */
 			virtual void run(void) {}
 
+			/**
+			 * Stop execution of the VM
+			 */
+			virtual void pause(void) {}
+
+
 			/*********************
 			 ** RPC declaration **
 			 *********************/
@@ -54,7 +60,9 @@ namespace Genode {
 			GENODE_RPC(Rpc_exception_handler, void, exception_handler,
 			           Signal_context_capability);
 			GENODE_RPC(Rpc_run, void, run);
-			GENODE_RPC_INTERFACE(Rpc_cpu_state, Rpc_exception_handler, Rpc_run);
+			GENODE_RPC(Rpc_pause, void, pause);
+			GENODE_RPC_INTERFACE(Rpc_cpu_state, Rpc_exception_handler,
+			                     Rpc_run, Rpc_pause);
 	};
 }
 

base-hw/src/core/include/vm_session_component.h

@@ -67,6 +67,7 @@ namespace Genode {
 			Dataspace_capability cpu_state(void) { return _ds_cap; }
 			void exception_handler(Signal_context_capability handler);
 			void run(void);
+			void pause(void);
 	};
 }
 

base-hw/src/core/kernel.cc

@@ -691,8 +691,13 @@ namespace Kernel
 			   Signal_context * const context)
 			: _state(state), _context(context) { }
 
-			void run() {
-				cpu_scheduler()->insert(this); }
+
+			/**************************
+			 ** Vm_session interface **
+			 **************************/
+
+			void run()   { cpu_scheduler()->insert(this); }
+			void pause() { cpu_scheduler()->remove(this); }
 
 
 			/**********************
@@ -1300,6 +1305,23 @@ namespace Kernel
 	}
 
 
+	/**
+	 * Do specific syscall for 'user', for details see 'syscall.h'
+	 */
+	void do_pause_vm(Thread * const user)
+	{
+		/* check permissions */
+		assert(user->pd_id() == core_id());
+
+		/* get targeted vm via its id */
+		Vm * const vm = Vm::pool()->object(user->user_arg_1());
+		assert(vm);
+
+		/* pause targeted vm */
+		vm->pause();
+	}
+
+
 	/**
 	 * Handle a syscall request
 	 *
@@ -1344,6 +1366,7 @@ namespace Kernel
 			/* 28         */ do_resume_faulter,
 			/* 29         */ do_ack_signal,
 			/* 30         */ do_kill_signal_context,
+			/* 31         */ do_pause_vm,
 		};
 		enum { MAX_SYSCALL = sizeof(handle_sysc)/sizeof(handle_sysc[0]) - 1 };
 

base-hw/src/core/vm_session_component.cc

@@ -44,6 +44,16 @@ void Vm_session_component::run(void)
 }
 
 
+void Vm_session_component::pause(void)
+{
+	if (!_vm_id) {
+		PWRN("No exception handler registered!");
+		return;
+	}
+	Kernel::pause_vm(_vm_id);
+}
+
+
 Vm_session_component::Vm_session_component(Rpc_entrypoint  *ds_ep,
                                            Range_allocator *ram_alloc,
                                            size_t           ram_quota)