base: extend PD session by system_control_cap

Per Affinity::Location a system control cap can be requested. The capability
provides an RPC interface to request and set Cpu_state, as provided by the
former Pd::managing_system(Cpu_state) method. Invocation of those system
control capabilities then *can* (see below) be executed on the desired CPU
as described by Affinity::Location.

The system control cap will be invalid for kernels that don't support
system_control/managing_system functionality at all.

The system control cap will be ever by the same, e.g. ignoring the
Affinity::Location parameter, if the used kernel doesn't support or doesn't
require the feature to execute the system control per CPU.

The commit is a preparation step to add guarded and selective x86 MSR
access per CPU.

Fixes #5009

repos/base/src/core/include/core_env.h

@@ -75,7 +75,8 @@ class Core::Core_env : public Noncopyable
 			            _region_map,
 			            *((Pager_entrypoint *)nullptr),
 			            "" /* args to native PD */,
-			            platform_specific().core_mem_alloc())
+			            platform_specific().core_mem_alloc(),
+			            *((Core::System_control *)nullptr))
 		{
 			_pd_session.init_cap_and_ram_accounts();
 		}

repos/base/src/core/include/pd_root.h

@@ -33,6 +33,7 @@ class Core::Pd_root : public Root_component<Pd_session_component>
 		Range_allocator  &_phys_alloc;
 		Region_map       &_local_rm;
 		Range_allocator  &_core_mem;
+		System_control   &_system_control;
 
 		/**
 		 * The RAM allocations of system management components are getting
@@ -91,7 +92,7 @@ class Core::Pd_root : public Root_component<Pd_session_component>
 				                     _virt_range_from_args(args),
 				                     _managing_system(args),
 				                     _local_rm, _pager_ep, args,
-				                     _core_mem);
+				                     _core_mem, _system_control);
 		}
 
 		void _upgrade_session(Pd_session_component *pd, const char *args) override
@@ -111,11 +112,13 @@ class Core::Pd_root : public Root_component<Pd_session_component>
 		        Range_allocator  &phys_alloc,
 		        Region_map       &local_rm,
 		        Allocator        &md_alloc,
-		        Range_allocator  &core_mem)
+		        Range_allocator  &core_mem,
+		        System_control   &system_control)
 		:
 			Root_component<Pd_session_component>(&ep, &md_alloc),
 			_ep(ep), _signal_ep(signal_ep), _pager_ep(pager_ep),
-			_phys_alloc(phys_alloc), _local_rm(local_rm), _core_mem(core_mem)
+			_phys_alloc(phys_alloc), _local_rm(local_rm), _core_mem(core_mem),
+			_system_control(system_control)
 		{ }
 };
 

repos/base/src/core/include/pd_session_component.h

@@ -30,6 +30,7 @@
 #include <constrained_core_ram.h>
 #include <platform_pd.h>
 #include <signal_broker.h>
+#include <system_control.h>
 #include <rpc_cap_factory.h>
 #include <ram_dataspace_factory.h>
 #include <native_pd_component.h>
@@ -52,6 +53,7 @@ class Core::Pd_session_component : public Session_object<Pd_session>
 		Constructible<Account<Ram_quota> > _ram_account { };
 
 		Rpc_entrypoint            &_ep;
+		Core::System_control      &_system_control;
 		Constrained_ram_allocator  _constrained_md_ram_alloc;
 		Constrained_core_ram       _constrained_core_ram_alloc;
 		Sliced_heap                _sliced_heap;
@@ -131,10 +133,12 @@ class Core::Pd_session_component : public Session_object<Pd_session>
 		                     Region_map       &local_rm,
 		                     Pager_entrypoint &pager_ep,
 		                     char const       *args,
-		                     Range_allocator  &core_mem)
+		                     Range_allocator  &core_mem,
+		                     Core::System_control &system_control)
 		:
 			Session_object(ep, resources, label, diag),
 			_ep(ep),
+			_system_control(system_control),
 			_constrained_md_ram_alloc(*this, _ram_quota_guard(), _cap_quota_guard()),
 			_constrained_core_ram_alloc(_ram_quota_guard(), _cap_quota_guard(), core_mem),
 			_sliced_heap(_constrained_md_ram_alloc, local_rm),
@@ -329,11 +333,17 @@ class Core::Pd_session_component : public Session_object<Pd_session>
 		Capability<Native_pd> native_pd() override { return _native_pd.cap(); }
 
 
-		/*******************************
-		 ** Managing system interface **
-		 *******************************/
+		/******************************
+		 ** System control interface **
+		 ******************************/
 
-		Managing_system_state managing_system(Managing_system_state const &) override;
+		Capability<System_control> system_control_cap(Affinity::Location const location) override
+		{
+			if (_managing_system == Managing_system::PERMITTED)
+				return _system_control.control_cap(location);
+
+			return { };
+		}
 
 
 		/*******************************************

repos/base/src/core/include/system_control.h

@@ -0,0 +1,36 @@
+/*
+ * \brief  Interface to get access to privileged system control capability
+ * \author Alexander Boettcher
+ * \date   2023-09-25
+ */
+
+/*
+ * Copyright (C) 2023 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _CORE__INCLUDE__SYSTEM_CONTROL_H_
+#define _CORE__INCLUDE__SYSTEM_CONTROL_H_
+
+
+#include <base/rpc_server.h>
+
+
+namespace Core {
+
+	class System_control;
+
+	System_control & init_system_control(Allocator &, Rpc_entrypoint &);
+}
+
+
+class Core::System_control : Interface
+{
+	public:
+
+		virtual Capability<Pd_session::System_control> control_cap(Affinity::Location) const = 0;
+};
+
+#endif /* _CORE__INCLUDE__SYSTEM_CONTROL_H_ */

repos/base/src/core/main.cc

@@ -29,6 +29,7 @@
 #include <core_env.h>
 #include <core_service.h>
 #include <signal_transmitter.h>
+#include <system_control.h>
 #include <rom_root.h>
 #include <rm_root.h>
 #include <cpu_root.h>
@@ -255,6 +256,8 @@ void Genode::bootstrap_component(Genode::Platform &)
 	using Trace_root              = Core::Trace::Root;
 	using Trace_session_component = Core::Trace::Session_component;
 
+	static Core::System_control &system_control = init_system_control(sliced_heap, ep);
+
 	static Rom_root    rom_root    (ep, ep, platform().rom_fs(), sliced_heap);
 	static Rm_root     rm_root     (ep, sliced_heap, core_ram_alloc, local_rm, pager_ep);
 	static Cpu_root    cpu_root    (core_ram_alloc, local_rm, ep, ep, pager_ep,
@@ -262,7 +265,8 @@ void Genode::bootstrap_component(Genode::Platform &)
 	static Pd_root     pd_root     (ep, core_env().signal_ep(), pager_ep,
 	                                platform().ram_alloc(),
 	                                local_rm, sliced_heap,
-	                                platform_specific().core_mem_alloc());
+	                                platform_specific().core_mem_alloc(),
+	                                system_control);
 	static Log_root    log_root    (ep, sliced_heap);
 	static Io_mem_root io_mem_root (ep, ep, platform().io_mem_alloc(),
 	                                platform().ram_alloc(), sliced_heap);

repos/base/src/core/pd_session_support.cc

@@ -22,6 +22,20 @@ bool Pd_session_component::assign_pci(addr_t, uint16_t) { return true; }
 
 void Pd_session_component::map(addr_t, addr_t) { }
 
-using State = Genode::Pd_session::Managing_system_state;
 
-State Pd_session_component::managing_system(State const &) { return State(); }
+class System_control_dummy : public System_control
+{
+	public:
+
+		Capability<Pd_session::System_control> control_cap(Affinity::Location) const override
+		{
+			return { };
+		}
+};
+
+
+System_control & Core::init_system_control(Allocator &, Rpc_entrypoint &)
+{
+	static System_control_dummy dummy { };
+	return dummy;
+}