platform_drv: skip assign device if iommu missing

Avoid red messages in the log on machines with no IOMMU, which recurring
confuse people.

Issue #2801

repos/os/src/drivers/acpi/acpi.cc

@@ -177,6 +177,10 @@ struct Device_scope : Genode::Mmio
 	};
 
 	unsigned count() const {
+		unsigned const length = read<Length>();
+		if (length < 6)
+			return 0;
+
 		unsigned paths = (read<Length>() - 6) / 2;
 		if (paths > MAX_PATHS) {
 			Genode::error("Device_scope: more paths (", paths, ") than"
@@ -187,6 +191,29 @@ struct Device_scope : Genode::Mmio
 	}
 };
 
+/* DMA Remapping Hardware Definition - Intel VT-d IO Spec - 8.3. */
+struct Dmar_drhd : Genode::Mmio
+{
+	struct Length  : Register<0x2, 16> { };
+	struct Flags   : Register<0x4,  8> { };
+	struct Segment : Register<0x6, 16> { };
+	struct Phys    : Register<0x8, 64> { };
+
+	Dmar_drhd(addr_t a) : Genode::Mmio(a) { }
+
+	template <typename FUNC>
+	void apply(FUNC const &func = [] () { } )
+	{
+		addr_t addr = base() + 16;
+		do {
+			Device_scope scope(addr);
+
+			func(scope);
+
+			addr = scope.base() + scope.read<Device_scope::Length>();
+		} while (addr < base() + read<Length>());
+	}
+};
 
 /* DMA Remapping Reporting structure - Intel VT-d IO Spec - 8.3. */
 struct Dmar_rmrr : Genode::Mmio
@@ -1366,8 +1393,12 @@ void Acpi::generate_report(Genode::Env &env, Genode::Allocator &alloc)
 		/* lambda definition for scope evaluation in rmrr */
 		auto func_scope = [&] (Device_scope const &scope)
 		{
+			if (!scope.count())
+				return;
+
 			xml.node("scope", [&] () {
 				xml.attribute("bus_start", scope.read<Device_scope::Bus>());
+				xml.attribute("type", scope.read<Device_scope::Type>());
 				for (unsigned j = 0 ; j < scope.count(); j++) {
 					xml.node("path", [&] () {
 						attribute_hex(xml, "dev",
@@ -1383,6 +1414,17 @@ void Acpi::generate_report(Genode::Env &env, Genode::Allocator &alloc)
 		     entry; entry = entry->next()) {
 
 			entry->apply([&] (Dmar_common const &dmar) {
+				if (dmar.read<Dmar_common::Type>() == Dmar_common::Type::DRHD) {
+					Dmar_drhd drhd(dmar.base());
+
+					xml.node("drhd", [&] () {
+						attribute_hex(xml, "phys", drhd.read<Dmar_drhd::Phys>());
+						attribute_hex(xml, "flags", drhd.read<Dmar_drhd::Flags>());
+						attribute_hex(xml, "segment", drhd.read<Dmar_drhd::Segment>());
+						drhd.apply(func_scope);
+					});
+				}
+
 				if (dmar.read<Dmar_common::Type>() != Dmar_common::Type::RMRR)
 					return;
 

repos/os/src/drivers/platform/spec/x86/pci_session_component.h

@@ -219,7 +219,7 @@ class Platform::Session_component : public Genode::Rpc_object<Session>
 		Genode::List<Device_component>     _device_list { };
 		Platform::Pci_buses               &_pci_bus;
 		Genode::Heap                      &_global_heap;
-		bool                               _no_device_pd = false;
+		bool                               _iommu;
 
 		/**
 		 * Registry of RAM dataspaces allocated by the session
@@ -463,7 +463,8 @@ class Platform::Session_component : public Genode::Rpc_object<Session>
 		                  Genode::Attached_io_mem_dataspace &pciconf,
 		                  Platform::Pci_buses               &buses,
 		                  Genode::Heap                      &global_heap,
-		                  char                        const *args)
+		                  char                        const *args,
+		                  bool                        const iommu)
 		:
 			_env(env),
 			_config(config),
@@ -472,7 +473,7 @@ class Platform::Session_component : public Genode::Rpc_object<Session>
 			_cap_guard(Genode::cap_quota_from_args(args)),
 			_md_alloc(_env_ram, env.rm()),
 			_label(Genode::label_from_args(args)),
-			_pci_bus(buses), _global_heap(global_heap)
+			_pci_bus(buses), _global_heap(global_heap), _iommu(iommu)
 		{
 			/* subtract the RPC session and session dataspace capabilities */
 			_cap_guard.withdraw(Genode::Cap_quota{2});
@@ -763,7 +764,7 @@ class Platform::Session_component : public Genode::Rpc_object<Session>
 		{
 			using namespace Genode;
 
-			if (!device || device->config_space() == ~0UL)
+			if (!device || device->config_space() == ~0UL || !_iommu)
 				return;
 
 			try {
@@ -840,6 +841,8 @@ class Platform::Root : public Genode::Root_component<Session_component>
 
 		Genode::Constructible<Platform::Pci_buses> _buses { };
 
+		bool _iommu { false };
+
 		void _parse_report_rom(Genode::Env &env, const char * acpi_rom,
 		                       bool acpi_platform)
 		{
@@ -914,6 +917,11 @@ class Platform::Root : public Genode::Root_component<Session_component>
 					continue;
 				}
 
+				if (node.has_type("drhd")) {
+					_iommu = true;
+					continue;
+				}
+
 				if (node.has_type("rmrr")) {
 					uint64_t mem_start = 0, mem_end = 0;
 					node.attribute("start").value(&mem_start);
@@ -1029,7 +1037,8 @@ class Platform::Root : public Genode::Root_component<Session_component>
 		{
 			try {
 				return  new (md_alloc())
-					Session_component(_env, _config, *_pci_confspace, *_buses, _heap, args);
+					Session_component(_env, _config, *_pci_confspace, *_buses,
+					                  _heap, args, _iommu);
 			}
 			catch (Genode::Session_policy::No_policy_defined) {
 				Genode::error("Invalid session request, no matching policy for ",

tool/run/boot_dir/hw

@@ -37,7 +37,7 @@ proc run_boot_dir {binaries} {
 	# generate static ACPI report for platform driver on Muen
 	if {[have_spec "muen"]} {
 		set fh [open "bin/acpi" "WRONLY CREAT TRUNC"]
-		puts $fh "<acpi><bdf start=\"0\" count=\"16384\" base=\"0xf8000000\"/></acpi>"
+		puts $fh "<acpi><bdf start=\"0\" count=\"16384\" base=\"0xf8000000\"/><drhd/></acpi>"
 		close $fh
 	}