migration: close kvm after cpr

cpr-transfer breaks vfio network connectivity to and from the guest, and
the host system log shows:
  irq bypass consumer (token 00000000a03c32e5) registration fails: -16
which is EBUSY.  This occurs because KVM descriptors are still open in
the old QEMU process.  Close them.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/1751493538-202042-4-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
index f5555cabe7..0e903cdd2f 100644
--- a/hw/vfio/cpr.c
+++ b/hw/vfio/cpr.c
@@ -190,3 +190,24 @@ const VMStateDescription vfio_cpr_pci_vmstate = {
         VMSTATE_END_OF_LIST()
     }
 };
+
+static NotifierWithReturn kvm_close_notifier;
+
+static int vfio_cpr_kvm_close_notifier(NotifierWithReturn *notifier,
+                                       MigrationEvent *e,
+                                       Error **errp)
+{
+    if (e->type == MIG_EVENT_PRECOPY_DONE) {
+        vfio_kvm_device_close();
+    }
+    return 0;
+}
+
+void vfio_cpr_add_kvm_notifier(void)
+{
+    if (!kvm_close_notifier.notify) {
+        migration_add_notifier_mode(&kvm_close_notifier,
+                                    vfio_cpr_kvm_close_notifier,
+                                    MIG_MODE_CPR_TRANSFER);
+    }
+}