ahci: routing policies based on device serial/model

Fixes #1882

repos/os/src/drivers/ahci/README

@@ -18,10 +18,13 @@ which client can access a certain device:
 !    <any-service> <parent /> <any-child /> </any-service>
 !  </route>
 !  <config>
-!    <policy label="test-ahci" device="0" />
+!    <!-- use model and serial number -->
+!    <policy label="test-ahci" model="QEMU HARDDISK" serial="QM00005" />
+!    <!-- use controller port number -->
 !    <policy label="bench" device="1" />
 !  </config>
 !</start>
 
-In the example above, a session request labeled with "test-ahci"
-gains access to device 0, while "bench" gains access to device 1.
+In the example above, a session request labeled with "test-ahci" gains access to
+a device with certain model and serial numbers, while "bench" gains access to
+device at port 1.

repos/os/src/drivers/ahci/ahci.cc

@@ -185,6 +185,19 @@ struct Ahci
 		return port_num < MAX_PORTS && ports[port_num] && !port_claimed[port_num] &&
 		       ports[port_num]->ready();
 	}
+
+	long device_number(const char *model_num, const char *serial_num)
+	{
+		for (long port_num = 0; port_num < MAX_PORTS; port_num++) {
+			Ata_driver* drv = dynamic_cast<Ata_driver *>(ports[port_num]);
+			if (!drv)
+				continue;
+
+			if (*drv->model == model_num && *drv->serial == serial_num)
+				return port_num;
+		}
+		return -1;
+	}
 };
 
 
@@ -220,4 +233,9 @@ bool Ahci_driver::is_avail(long device_num)
 }
 
 
+long Ahci_driver::device_number(char const *model_num, char const *serial_num)
+{
+	return sata_ahci()->device_number(model_num, serial_num);
+}
+
 

repos/os/src/drivers/ahci/ahci.h

@@ -39,6 +39,7 @@ namespace Ahci_driver {
 	void init(Ahci_root &ep);
 
 	bool is_avail(long device_num);
+	long device_number(char const *model_num, char const *serial_num);
 
 	Block::Driver *claim_port(long device_num);
 	void           free_port(long device_num);

repos/os/src/drivers/ahci/ata_driver.h

@@ -26,6 +26,9 @@ struct Identity : Genode::Mmio
 {
 	Identity(Genode::addr_t base) : Mmio(base) { }
 
+	struct Serial_number : Register_array<0x14, 8, 20, 8> { };
+	struct Model_number : Register_array<0x36, 8, 40, 8> { };
+
 	struct Queue_depth : Register<0x96, 16>
 	{
 		struct Max_depth : Bitfield<0, 5> { };
@@ -71,6 +74,40 @@ struct Identity : Genode::Mmio
 	}
 };
 
+
+/**
+ * 16-bit word big endian device ASCII characters
+ */
+template <typename DEVICE_STRING>
+struct String
+{
+	char buf[DEVICE_STRING::ITEMS + 1];
+
+	String(Identity & info)
+	{
+		long j = 0;
+		for (unsigned long i = 0; i < DEVICE_STRING::ITEMS; i++) {
+			/* read and swap even and uneven characters */
+			char c = (char)info.read<DEVICE_STRING>(i ^ 1);
+			if (Genode::is_whitespace(c) && j == 0)
+				continue;
+			buf[j++] = c;
+		}
+
+		buf[j] = 0;
+
+		/* remove trailing white spaces */
+		while ((j > 0) && (buf[--j] == ' '))
+			buf[j] = 0;
+	}
+
+	bool operator == (char const *other) const
+	{
+		return strcmp(buf, other) == 0;
+	}
+};
+
+
 /**
  * Commands to distinguish between ncq and non-ncq operation
  */
@@ -135,9 +172,15 @@ struct Dma_ext_command : Io_command
  */
 struct Ata_driver : Port_driver
 {
-	Genode::Lazy_volatile_object<Identity>   info;
-	Io_command                              *io_cmd = nullptr;
-	Block::Packet_descriptor                 pending[32];
+	typedef ::String<Identity::Serial_number> Serial_string;
+	typedef ::String<Identity::Model_number>  Model_string;
+
+	Genode::Lazy_volatile_object<Identity>      info;
+	Genode::Lazy_volatile_object<Serial_string> serial;
+	Genode::Lazy_volatile_object<Model_string>  model;
+
+	Io_command                               *io_cmd = nullptr;
+	Block::Packet_descriptor                  pending[32];
 
 	Ata_driver(Port &port, Signal_context_capability state_change)
 	: Port_driver(port, state_change)
@@ -242,8 +285,14 @@ struct Ata_driver : Port_driver
 
 			if (Port::Is::Dss::get(status) || Port::Is::Pss::get(status)) {
 				info.construct(device_info);
-				if (verbose)
+				serial.construct(*info);
+				model.construct(*info);
+
+				if (verbose) {
+					PLOG("\t\tmodel number: %s", model->buf);
+					PLOG("\t\tserial number: %s", serial->buf);
 					info->info();
+				}
 
 				check_device();
 				if (ncq_support())

repos/os/src/drivers/ahci/main.cc

@@ -61,27 +61,32 @@ class Block::Root_multiple_clients : public Root_component< ::Session_component>
 
 		Server::Entrypoint &_ep;
 
-		long _device_num(const char *session_label)
+		long _device_num(const char *session_label, char *model, char *sn, size_t bufs_len)
 		{
 			long num = -1;
 
-			try {
-				using namespace Genode;
+			Xml_node policy = config()->xml_node().sub_node("policy");
 
-				Xml_node policy = Genode::config()->xml_node().sub_node("policy");
+			for (;; policy = policy.next("policy")) {
+				char label_buf[64];
+				policy.attribute("label").value(label_buf, sizeof(label_buf));
 
-				for (;; policy = policy.next("policy")) {
-					char label_buf[64];
-					policy.attribute("label").value(label_buf, sizeof(label_buf));
+				if (Genode::strcmp(session_label, label_buf))
+					continue;
 
-					if (Genode::strcmp(session_label, label_buf))
-						continue;
-
-					/* read device attribute */
+				/* try read device port number attribute */
+				try {
 					policy.attribute("device").value(&num);
-					break;
-				}
-			} catch (...) {}
+				} catch (...) { }
+
+				/* try read device model and serial number attributes */
+				try {
+					model[0] = sn[0] = 0;
+					policy.attribute("model").value(model, bufs_len);
+					policy.attribute("serial").value(sn, bufs_len);
+				} catch (...) { }
+				break;
+			}
 
 			return num;
 		}
@@ -96,12 +101,16 @@ class Block::Root_multiple_clients : public Root_component< ::Session_component>
 			/* TODO: build quota check */
 
 			/* Search for configured device */
-			char label_buf[64];
+			char label_buf[64], model_buf[64], sn_buf[64];
 			Genode::Arg_string::find_arg(args,
 			                             "label").string(label_buf,
 			                                             sizeof(label_buf),
 			                                             "<unlabeled>");
-			long num = _device_num(label_buf);
+			long num = _device_num(label_buf, model_buf, sn_buf, sizeof(model_buf));
+			/* prefer model/serial routing */
+			if ((model_buf[0] != 0) && (sn_buf[0] != 0))
+				num = Ahci_driver::device_number(model_buf, sn_buf);
+
 			if (num < 0) {
 				PERR("No confguration found for client: %s", label_buf);
 				throw Root::Invalid_args();