usb-host: claim port

When configured to pass through a specific host port (using hostbus and
hostport properties), try to claim the port if supported by the kernel.
That will avoid any kernel drivers binding to devices plugged into that
port.  It will not stop any userspace apps (such as usb_modeswitch)
access the device via usbfs though.

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

trace-events

@@ -263,6 +263,7 @@ usb_host_ep_stop_iso(int bus, int addr, int ep) "dev %d:%d, ep %d"
 usb_host_reset(int bus, int addr) "dev %d:%d"
 usb_host_auto_scan_enabled(void)
 usb_host_auto_scan_disabled(void)
+usb_host_claim_port(int bus, int hub, int port) "bus %d, hub addr %d, port %d"
 
 # hw/scsi-bus.c
 scsi_req_alloc(int target, int lun, int tag) "target %d lun %d tag %d"

usb-linux.c

@@ -115,6 +115,7 @@ struct USBAutoFilter {
 typedef struct USBHostDevice {
     USBDevice dev;
     int       fd;
+    int       hub_fd;
 
     uint8_t   descr[8192];
     int       descr_len;
@@ -525,6 +526,9 @@ static void usb_host_handle_destroy(USBDevice *dev)
     USBHostDevice *s = (USBHostDevice *)dev;
 
     usb_host_close(s);
+    if (s->hub_fd != -1) {
+        close(s->hub_fd);
+    }
     QTAILQ_REMOVE(&hostdevs, s, next);
     qemu_remove_exit_notifier(&s->exit);
 }
@@ -1266,10 +1270,63 @@ static int usb_host_initfn(USBDevice *dev)
 
     dev->auto_attach = 0;
     s->fd = -1;
+    s->hub_fd = -1;
+
     QTAILQ_INSERT_TAIL(&hostdevs, s, next);
     s->exit.notify = usb_host_exit_notifier;
     qemu_add_exit_notifier(&s->exit);
     usb_host_auto_check(NULL);
+
+#ifdef USBDEVFS_CLAIM_PORT
+    if (s->match.bus_num != 0 && s->match.port != NULL) {
+        char *h, hub_name[64], line[1024];
+        int hub_addr, portnr, ret;
+
+        snprintf(hub_name, sizeof(hub_name), "%d-%s",
+                 s->match.bus_num, s->match.port);
+
+        /* try strip off last ".$portnr" to get hub */
+        h = strrchr(hub_name, '.');
+        if (h != NULL) {
+            portnr = atoi(h+1);
+            *h = '\0';
+        } else {
+            /* no dot in there -> it is the root hub */
+            snprintf(hub_name, sizeof(hub_name), "usb%d",
+                     s->match.bus_num);
+            portnr = atoi(s->match.port);
+        }
+
+        if (!usb_host_read_file(line, sizeof(line), "devnum",
+                                hub_name)) {
+            goto out;
+        }
+        if (sscanf(line, "%d", &hub_addr) != 1) {
+            goto out;
+        }
+
+        if (!usb_host_device_path) {
+            goto out;
+        }
+        snprintf(line, sizeof(line), "%s/%03d/%03d",
+                 usb_host_device_path, s->match.bus_num, hub_addr);
+        s->hub_fd = open(line, O_RDWR | O_NONBLOCK);
+        if (s->hub_fd < 0) {
+            goto out;
+        }
+
+        ret = ioctl(s->hub_fd, USBDEVFS_CLAIM_PORT, &portnr);
+        if (ret < 0) {
+            close(s->hub_fd);
+            s->hub_fd = -1;
+            goto out;
+        }
+
+        trace_usb_host_claim_port(s->match.bus_num, hub_addr, portnr);
+    }
+out:
+#endif
+
     return 0;
 }