[QEMU HCI-8.0 PATCH v2 03/13] usb-host: add migration blocker for CPR modes #VSTOR-137800

[Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>]

We're about to add support for CPR migration to usb-host in the upcoming
commits.  Right now CPR is crashing with usb-host devices.  Let's add
migration blocker upfront, for both cpr-exec and cpr-transfer.  The
blocker is added unconditionally, so that we resuse CPR migration instead
of crashing on it.  That is for the sake of bisectability of the upcoming
commits.  It is going to be lifted (conditioned) in a following patch
once CPR support is added.  Also, blocker is added at the end of
usb_host_realize(), so we have to cleanup all the side effects done
earlier in .realize() in case migrate_add_blocker_modes() fails.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 hw/usb/host-libusb.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index a8e6f142ec0..86f96087085 100644
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -46,6 +46,7 @@
 #endif
 
 #include "qapi/error.h"
+#include "migration/blocker.h"
 #include "migration/vmstate.h"
 #include "monitor/monitor.h"
 #include "qemu/error-report.h"
@@ -103,6 +104,7 @@ struct USBHostDevice {
     char                             port[16];
 
     int                              hostfd;
+    Error                            *cpr_blocker;
     libusb_device                    *dev;
     libusb_device_handle             *dh;
     struct libusb_device_descriptor  ddesc;
@@ -1254,6 +1256,18 @@ static void usb_host_realize(USBDevice *udev, Error **errp)
 
     s->exit.notify = usb_host_exit_notifier;
     qemu_add_exit_notifier(&s->exit);
+
+    error_setg(&s->cpr_blocker, "usb-host device %s does not support CPR: ",
+               DEVICE(s)->id ?: "(anonymous)");
+    if (migrate_add_blocker_modes(&s->cpr_blocker, errp,
+                                  MIG_MODE_CPR_TRANSFER,
+                                  MIG_MODE_CPR_EXEC, -1) < 0) {
+        qemu_remove_exit_notifier(&s->exit);
+        if (s->needs_autoscan) {
+            QTAILQ_REMOVE(&hostdevs, s, next);
+        }
+        usb_host_close(s);
+    }
 }
 
 static void usb_host_instance_init(Object *obj)
@@ -1275,6 +1289,7 @@ static void usb_host_unrealize(USBDevice *udev)
         QTAILQ_REMOVE(&hostdevs, s, next);
     }
     usb_host_close(s);
+    migrate_del_blocker(&s->cpr_blocker);
 }
 
 static void usb_host_cancel_packet(USBDevice *udev, USBPacket *p)
-- 
2.47.1