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/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)