vm_session: return vcpu id when creating vcpu

Ref #3553

repos/base-nova/src/core/include/vm_session_component.h

@@ -78,6 +78,7 @@ class Genode::Vm_session_component
 
 				addr_t new_pt_id();
 
+				Vcpu_id id() { return _id; }
 				bool match(Vcpu_id const id) const { return id.id == _id.id; }
 				Ram_dataspace_capability ds_cap() const { return _ds_cap; }
 
@@ -180,7 +181,7 @@ class Genode::Vm_session_component
 		void attach(Dataspace_capability, addr_t, Attach_attr) override;
 		void attach_pic(addr_t) override {}
 		void detach(addr_t, size_t) override;
-		void _create_vcpu(Thread_capability);
+		Vcpu_id _create_vcpu(Thread_capability);
 };
 
 #endif /* _CORE__VM_SESSION_COMPONENT_H_ */

repos/base-nova/src/core/vm_session_component.cc

@@ -33,6 +33,7 @@
 
 using Genode::addr_t;
 using Genode::Vm_session_component;
+using Vcpu_id = Genode::Vm_session::Vcpu_id;
 
 enum { CAP_RANGE_LOG2 = 2, CAP_RANGE = 1 << CAP_RANGE_LOG2 };
 
@@ -153,10 +154,10 @@ static Genode::uint8_t _with_kernel_quota_upgrade(addr_t const pd_target,
 	return res;
 }
 
-void Vm_session_component::_create_vcpu(Thread_capability cap)
+Vcpu_id Vm_session_component::_create_vcpu(Thread_capability cap)
 {
-	if (!cap.valid())
-		return;
+	Vcpu_id ret;
+	if (!cap.valid()) return ret;
 
 	/* lookup vmm pd and cpu location of handler thread in VMM */
 	addr_t             kernel_cpu_id = 0;
@@ -178,7 +179,7 @@ void Vm_session_component::_create_vcpu(Thread_capability cap)
 
 	/* if VMM pd lookup failed then deny to create vCPU */
 	if (!vmm_pd_sel || vmm_pd_sel == Vcpu::invalid())
-		return;
+		return ret;
 
 	/* allocate vCPU object */
 	Vcpu &vcpu = *new (_heap) Vcpu(_constrained_md_ram_alloc,
@@ -191,7 +192,7 @@ void Vm_session_component::_create_vcpu(Thread_capability cap)
 
 	/* we ran out of caps in core */
 	if (!vcpu.ds_cap().valid())
-		return;
+		return ret;
 
 	/* core PD selector */
 	addr_t const core_pd = platform_specific().core_pd_sel();
@@ -204,7 +205,7 @@ void Vm_session_component::_create_vcpu(Thread_capability cap)
 	if (res != Nova::NOVA_OK) {
 		error("create_sm = ", res);
 		destroy(_heap, &vcpu);
-		return;
+		return ret;
 	}
 
 	addr_t const event_base = (1U << Nova::NUM_INITIAL_VCPU_PT_LOG2) * _id_alloc;
@@ -217,7 +218,7 @@ void Vm_session_component::_create_vcpu(Thread_capability cap)
 	if (res != Nova::NOVA_OK) {
 		error("create_ec = ", res);
 		destroy(_heap, &vcpu);
-		return;
+		return ret;
 	}
 
 	addr_t const dst_sm_ec_sel = Nova::NUM_INITIAL_PT_RESERVED
@@ -239,11 +240,12 @@ void Vm_session_component::_create_vcpu(Thread_capability cap)
 	{
 		error("map sm ", res, " ", _id_alloc);
 		destroy(_heap, &vcpu);
-		return;
+		return ret;
 	}
 
-	_id_alloc++;
 	_vcpus.insert(&vcpu);
+	_id_alloc++;
+	return vcpu.id();
 }
 
 void Vm_session_component::_run(Vcpu_id const vcpu_id)

repos/base-nova/src/lib/base/vm_session.cc

@@ -29,7 +29,6 @@ using namespace Genode;
 struct Vcpu;
 
 static Genode::Registry<Genode::Registered<Vcpu> > vcpus;
-static unsigned vcpu_id = 0;
 
 struct Vcpu {
 
@@ -425,8 +424,9 @@ struct Vcpu {
 
 	public:
 
-		Vcpu(Vm_handler_base &o, unsigned id, Allocator &alloc)
-		: _obj(o), _alloc(alloc), _id({id}) { }
+		Vcpu(Vm_handler_base &o, Vm_session::Vcpu_id const id,
+		     Allocator &alloc)
+		: _obj(o), _alloc(alloc), _id(id) { }
 
 		virtual ~Vcpu() { }
 
@@ -703,9 +703,10 @@ Vm_session_client::create_vcpu(Allocator &alloc, Env &env,
                                Vm_handler_base &handler)
 {
 	Thread * ep = reinterpret_cast<Thread *>(&handler._rpc_ep);
-	call<Rpc_create_vcpu>(ep->cap());
 
-	Vcpu * vcpu = new (alloc) Registered<Vcpu> (vcpus, handler, vcpu_id++, alloc);
+	Vcpu * vcpu = new (alloc) Registered<Vcpu> (vcpus, handler,
+	                                            call<Rpc_create_vcpu>(ep->cap()),
+	                                            alloc);
 	vcpu->assign_ds_state(env.rm(), call<Rpc_cpu_state>(vcpu->id()));
 
 	Signal_context_capability dontcare_exit;