platform_drv/x86: support to disable MSI-X

+ disable for wifi driver MSI-X

Issue #4079

repos/base/run/platform_drv.inc

@@ -107,7 +107,7 @@ proc platform_drv_policy {} {
 			<policy label_prefix="ps2_drv">  <device name="PS2"/> </policy>
 			<policy label_prefix="nic_drv">  <pci class="ETHERNET"/> </policy>
 			<policy label_prefix="fb_drv">   <pci class="VGA"/> </policy>
-			<policy label_prefix="wifi_drv"> <pci class="WIFI"/> </policy>
+			<policy label_prefix="wifi_drv" msix="false"> <pci class="WIFI"/> </policy>
 			<policy label_prefix="usb_drv">  <pci class="USB"/> </policy>
 			<policy label_prefix="ahci_drv"> <pci class="AHCI"/> </policy>
 			<policy label_prefix="nvme_drv"> <pci class="NVME"/> </policy>

repos/gems/recipes/raw/drivers_managed-pc/drivers.config

@@ -124,7 +124,7 @@
 				<pci bus="0" device="0" function="0"/>
 				<pci class="ISABRIDGE"/>
 			</policy>
-			<policy label_suffix="-> wifi">  <pci class="WIFI"/> </policy>
+			<policy label_suffix="-> wifi" msix="false">  <pci class="WIFI"/> </policy>
 			<policy label_suffix="-> nic">   <pci class="ETHERNET"/> </policy>
 			<policy label_suffix="-> audio"> <pci class="AUDIO"/> <pci class="HDAUDIO"/> </policy>
 			<policy label="acpica"> </policy>

repos/os/src/drivers/platform/spec/x86/README

@@ -66,13 +66,15 @@ the device specified by the triple, the device will not appear during device
 discovery by the client with the fuzzy pci class policy.
 
 
-By default the driver will try to use MSIs if the device and the used kernel
+By default the driver will try to use first MSI-X, then MSI and finally GSI.
-supports it. This behaviour can be overwritten:
+However, the MSI-X/MSI feature depends on the support by the used kernel and
+the PCI capabilities of the device. The MSI and MSI-X feature can be disabled
+explicitly by configuration, e.g.:
 
 !<start name="platform_drv" managing_system="yes">
 ! <resource name="RAM" quantum="8M"/>
 ! <config>
-!  <policy label_prefix="nic_drv" irq_mode="nomsi">
+!  <policy label_prefix="nic_drv" msi="false" msix="false">
 !  ...
 !  </policy>
 ! </config>

repos/os/src/drivers/platform/spec/x86/pci_device.cc

@@ -175,10 +175,11 @@ Genode::Irq_session_capability Platform::Device_component::irq(uint8_t id)
 
 	uint16_t const msi_cap  = _msi_cap();
 	uint16_t const msix_cap = _msix_cap();
-
+	bool const try_msi_msix = (_session.msi_usage()  && msi_cap) ||
+	                          (_session.msix_usage() && msix_cap);
 	_irq_session = construct_at<Irq_session_component>(_mem_irq_component,
 	                                                   _configure_irq(_irq_line, msi_cap, msix_cap),
-	                                                   (!_session.msi_usage() || (!msi_cap && !msix_cap)) ? ~0UL : _config_space,
+	                                                   try_msi_msix ? _config_space : ~0UL,
 	                                                   _env, _global_heap);
 	_env.ep().rpc_ep().manage(_irq_session);
 
@@ -186,7 +187,7 @@ Genode::Irq_session_capability Platform::Device_component::irq(uint8_t id)
 	bool msi_used = false;
 
 	if (_irq_session->msi()) {
-		if (msix_cap)
+		if (_session.msix_usage() && msix_cap)
 			msix_used = _setup_msix(msix_cap);
 		if (!msix_used && msi_cap)
 			msi_used = _setup_msi(msi_cap);

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

@@ -221,7 +221,8 @@ class Platform::Session_component : public Rpc_object<Session>
 		Pci::Config::Delayer      &_delayer;
 		Device_bars_pool          &_devices_bars;
 		bool                       _iommu;
-		bool                       _msi_usage { true };
+		bool                       _msi_usage  { true };
+		bool                       _msix_usage { true };
 
 		/**
 		 * Registry of RAM dataspaces allocated by the session
@@ -499,8 +500,9 @@ class Platform::Session_component : public Rpc_object<Session>
 		{
 			Session_policy const policy { _label, _config.xml() };
 
-			typedef String<10> Mode;
+			_msi_usage  = policy.attribute_value("msi", _msi_usage);
-			_msi_usage = policy.attribute_value("irq_mode", Mode()) != "nomsi";
+			_msix_usage = _msi_usage &&
+			              policy.attribute_value("msix", _msix_usage);
 
 			/* check policy for non-pci devices */
 			policy.for_each_sub_node("device", [&] (Xml_node device_node) {
@@ -656,6 +658,11 @@ class Platform::Session_component : public Rpc_object<Session>
 		bool msi_usage() const { return _msi_usage; }
 
 
+		/**
+		 * Check whether msi-x usage was explicitly switched off
+		 */
+		bool msix_usage() const { return _msix_usage; }
+
 		/***************************
 		 ** PCI session interface **
 		 ***************************/

repos/ports/run/netperf.inc

@@ -180,7 +180,7 @@ source ${genode_dir}/repos/base/run/platform_drv.inc
 proc platform_drv_policy {} {
 	global use_wifi_driver
 	if { $use_wifi_driver } {
-		return {<policy label_prefix="nic_drv"> <pci class="WIFI"/> </policy>}}
+		return {<policy label_prefix="nic_drv" msix="false"> <pci class="WIFI"/> </policy>}}
 	return {<policy label_prefix="usb_host_drv"> <pci class="USB"/> </policy>}
 }