[Qemu-devel] [PATCH] usb/vmstate: add parent dev path

[Gerd Hoffmann <kraxel@redhat.com>]

... to make vmstate id string truely unique with multiple host
controllers, i.e. move from "1/usb-ptr" to "0000:00:01.3/1/usb-ptr"
(usb tabled connected to piix3 uhci).

This obviously breaks migration.  To handle this the usb bus
property "full-path" is added.  When setting this to false old
behavior is maintained.  This way current qemu will be compatible
with old versions when started using '-M pc-$oldversion'.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/pc_piix.c |   28 ++++++++++++++++++++++++++++
 hw/usb.h     |    5 +++++
 hw/usb/bus.c |   18 +++++++++++++++++-
 3 files changed, 50 insertions(+), 1 deletions(-)

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 3f99f9a..8cb7d5f 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -386,6 +386,10 @@ static QEMUMachine pc_machine_v1_0 = {
             .driver   = "isa-fdc",
             .property = "check_media_rate",
             .value    = "off",
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     },
@@ -405,6 +409,10 @@ static QEMUMachine pc_machine_v0_15 = {
             .driver   = "isa-fdc",
             .property = "check_media_rate",
             .value    = "off",
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     },
@@ -449,6 +457,10 @@ static QEMUMachine pc_machine_v0_14 = {
             .driver   = "pc-sysfw",
             .property = "rom_only",
             .value    = stringify(1),
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     },
@@ -505,6 +517,10 @@ static QEMUMachine pc_machine_v0_13 = {
             .driver   = "pc-sysfw",
             .property = "rom_only",
             .value    = stringify(1),
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     },
@@ -565,6 +581,10 @@ static QEMUMachine pc_machine_v0_12 = {
             .driver   = "pc-sysfw",
             .property = "rom_only",
             .value    = stringify(1),
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     }
@@ -633,6 +653,10 @@ static QEMUMachine pc_machine_v0_11 = {
             .driver   = "pc-sysfw",
             .property = "rom_only",
             .value    = stringify(1),
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     }
@@ -713,6 +737,10 @@ static QEMUMachine pc_machine_v0_10 = {
             .driver   = "pc-sysfw",
             .property = "rom_only",
             .value    = stringify(1),
+        },{
+            .driver   = "USB",
+            .property = "full-path",
+            .value    = "no",
         },
         { /* end of list */ }
     },
diff --git a/hw/usb.h b/hw/usb.h
index e95085f..ae7ccda 100644
--- a/hw/usb.h
+++ b/hw/usb.h
@@ -182,12 +182,17 @@ struct USBEndpoint {
     QTAILQ_HEAD(, USBPacket) queue;
 };
 
+enum USBDeviceFlags {
+    USB_DEV_FLAG_FULL_PATH,
+};
+
 /* definition of a USB device */
 struct USBDevice {
     DeviceState qdev;
     USBPort *port;
     char *port_path;
     void *opaque;
+    uint32_t flags;
 
     /* Actual connected speed */
     int speed;
diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index d3f8358..f1e567b 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -19,6 +19,8 @@ static struct BusInfo usb_bus_info = {
     .get_fw_dev_path = usb_get_fw_dev_path,
     .props      = (Property[]) {
         DEFINE_PROP_STRING("port", USBDevice, port_path),
+        DEFINE_PROP_BIT("full-path", USBDevice, flags,
+                        USB_DEV_FLAG_FULL_PATH, true),
         DEFINE_PROP_END_OF_LIST()
     },
 };
@@ -460,7 +462,21 @@ static void usb_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 static char *usb_get_dev_path(DeviceState *qdev)
 {
     USBDevice *dev = USB_DEVICE(qdev);
-    return g_strdup(dev->port->path);
+    DeviceState *hcd = qdev->parent_bus->parent;
+    char *id = NULL;
+
+    if ((dev->flags & (1 << USB_DEV_FLAG_FULL_PATH)) &&
+        hcd && hcd->parent_bus && hcd->parent_bus->info->get_dev_path) {
+        id = hcd->parent_bus->info->get_dev_path(hcd);
+    }
+    if (id) {
+        int len = strlen(id)+strlen(dev->port->path)+2;
+        char *ret = g_malloc(len);
+        snprintf(ret, len, "%s/%s", id, dev->port->path);
+        return ret;
+    } else {
+        return g_strdup(dev->port->path);
+    }
 }
 
 static char *usb_get_fw_dev_path(DeviceState *qdev)
-- 
1.7.1