usb: add serial number generator

This patch adds a function which creates unique serial numbers for usb
devices and puts it into use.  Windows guests tend to become unhappy if
they find two identical usb devices in the system.  Effects range from
non-functional devices (with yellow exclamation mark in device manager)
to BSODs.  Handing out unique serial numbers to devices fixes this.

With this patch applied almost all emulated devices get a generated,
unique serial number.  There are two exceptions:

 * usb-storage devices will prefer a user-specified serial number
   and will only get a generated number in case the serial property
   is unset.
 * usb-hid devices keep the fixed serial number "42" as it is used
   to signal "remote wakeup actually works".
   See commit 7b074a22da

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb/desc.c

@@ -1,3 +1,5 @@
+#include <ctype.h>
+
 #include "hw/usb.h"
 #include "hw/usb/desc.h"
 #include "trace.h"
@@ -412,6 +414,36 @@ void usb_desc_set_string(USBDevice *dev, uint8_t index, const char *str)
     s->str = g_strdup(str);
 }
 
+/*
+ * This function creates a serial number for a usb device.
+ * The serial number should:
+ *   (a) Be unique within the virtual machine.
+ *   (b) Be constant, so you don't get a new one each
+ *       time the guest is started.
+ * So we are using the physical location to generate a serial number
+ * from it.  It has three pieces:  First a fixed, device-specific
+ * prefix.  Second the device path of the host controller (which is
+ * the pci address in most cases).  Third the physical port path.
+ * Results in serial numbers like this: "314159-0000:00:1d.7-3".
+ */
+void usb_desc_create_serial(USBDevice *dev)
+{
+    DeviceState *hcd = dev->qdev.parent_bus->parent;
+    const USBDesc *desc = usb_device_get_usb_desc(dev);
+    int index = desc->id.iSerialNumber;
+    char serial[64];
+    int dst;
+
+    assert(index != 0 && desc->str[index] != NULL);
+    dst = snprintf(serial, sizeof(serial), "%s", desc->str[index]);
+    if (hcd && hcd->parent_bus && hcd->parent_bus->info->get_dev_path) {
+        char *path = hcd->parent_bus->info->get_dev_path(hcd);
+        dst += snprintf(serial+dst, sizeof(serial)-dst, "-%s", path);
+    }
+    dst += snprintf(serial+dst, sizeof(serial)-dst, "-%s", dev->port->path);
+    usb_desc_set_string(dev, index, serial);
+}
+
 const char *usb_desc_get_string(USBDevice *dev, uint8_t index)
 {
     USBDescString *s;

hw/usb/desc.h

@@ -171,6 +171,7 @@ int usb_desc_other(const USBDescOther *desc, uint8_t *dest, size_t len);
 void usb_desc_init(USBDevice *dev);
 void usb_desc_attach(USBDevice *dev);
 void usb_desc_set_string(USBDevice *dev, uint8_t index, const char *str);
+void usb_desc_create_serial(USBDevice *dev);
 const char *usb_desc_get_string(USBDevice *dev, uint8_t index);
 int usb_desc_string(USBDevice *dev, int index, uint8_t *dest, size_t len);
 int usb_desc_get_descriptor(USBDevice *dev, int value, uint8_t *dest, size_t len);

hw/usb/dev-audio.c

@@ -648,6 +648,7 @@ static int usb_audio_initfn(USBDevice *dev)
 {
     USBAudioState *s = DO_UPCAST(USBAudioState, dev, dev);
 
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
     s->dev.opaque = s;
     AUD_register_card("usb-audio", &s->card);

hw/usb/dev-bluetooth.c

@@ -494,6 +494,7 @@ static void usb_bt_handle_destroy(USBDevice *dev)
 
 static int usb_bt_initfn(USBDevice *dev)
 {
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
     return 0;
 }

hw/usb/dev-hub.c

@@ -520,6 +520,7 @@ static int usb_hub_initfn(USBDevice *dev)
     USBHubPort *port;
     int i;
 
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
     s->intr = usb_ep_get(dev, USB_TOKEN_IN, 1);
     for (i = 0; i < NUM_PORTS; i++) {

hw/usb/dev-network.c

@@ -1324,6 +1324,7 @@ static int usb_net_initfn(USBDevice *dev)
 {
     USBNetState *s = DO_UPCAST(USBNetState, dev, dev);
 
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
 
     s->rndis_state = RNDIS_UNINITIALIZED;

hw/usb/dev-serial.c

@@ -479,6 +479,7 @@ static int usb_serial_initfn(USBDevice *dev)
 {
     USBSerialState *s = DO_UPCAST(USBSerialState, dev, dev);
 
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
 
     if (!s->cs) {

hw/usb/dev-smartcard-reader.c

@@ -1189,6 +1189,7 @@ static int ccid_initfn(USBDevice *dev)
 {
     USBCCIDState *s = DO_UPCAST(USBCCIDState, dev, dev);
 
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
     qbus_create_inplace(&s->bus.qbus, &ccid_bus_info, &dev->qdev, NULL);
     s->intr = usb_ep_get(dev, USB_TOKEN_IN, CCID_INT_IN_EP);

hw/usb/dev-storage.c

@@ -546,6 +546,8 @@ static int usb_msd_initfn(USBDevice *dev)
     }
     if (s->serial) {
         usb_desc_set_string(dev, STR_SERIALNUMBER, s->serial);
+    } else {
+        usb_desc_create_serial(dev);
     }
 
     usb_desc_init(dev);

hw/usb/dev-wacom.c

@@ -339,6 +339,7 @@ static void usb_wacom_handle_destroy(USBDevice *dev)
 static int usb_wacom_initfn(USBDevice *dev)
 {
     USBWacomState *s = DO_UPCAST(USBWacomState, dev, dev);
+    usb_desc_create_serial(dev);
     usb_desc_init(dev);
     s->changed = 1;
     return 0;