Hi Steve I tested your patch which hit a problem under enable/disable nic mq state(The full test scenario is live migration vm at local under enable/disable vm nic mq state): Run command: /qemu-img info /home/images/vm1.qcow2 --output=json Error info: qemu-img: Could not open '/home/images/vm1.qcow2': Failed to get shared "write" lock
In the same environment if I remove the enable/disable nic mq steps, it can work well. Note: This issue has not been reproduced 100%, but in order to confirm this is really a bug, I test the following: 1. Live migration vm at local under enable/disable nic mq state: 3/5 reproduce ratio 2. Only live migration 5 times are all passed. Thanks Lei On Fri, Jul 18, 2025 at 4:48 AM Steve Sistare <steven.sist...@oracle.com> wrote: > > Tap and vhost devices can be preserved during cpr-transfer using > traditional live migration methods, wherein the management layer > creates new interfaces for the target and fiddles with 'ip link' > to deactivate the old interface and activate the new. > > However, CPR can simply send the file descriptors to new QEMU, > with no special management actions required. The user enables > this behavior by specifing '-netdev tap,cpr=on'. The default > is cpr=off. > > Steve Sistare (8): > migration: stop vm earlier for cpr > migration: cpr setup notifier > vhost: reset vhost devices for cpr > cpr: delete all fds > Revert "vhost-backend: remove vhost_kernel_reset_device()" > tap: common return label > tap: cpr support > tap: postload fix for cpr > > qapi/net.json | 5 +- > include/hw/virtio/vhost.h | 1 + > include/migration/cpr.h | 3 +- > include/net/tap.h | 1 + > hw/net/virtio-net.c | 20 +++++++ > hw/vfio/device.c | 2 +- > hw/virtio/vhost-backend.c | 6 ++ > hw/virtio/vhost.c | 32 +++++++++++ > migration/cpr.c | 24 ++++++-- > migration/migration.c | 38 ++++++++----- > net/tap-win32.c | 5 ++ > net/tap.c | 141 > +++++++++++++++++++++++++++++++++++----------- > 12 files changed, 223 insertions(+), 55 deletions(-) > > -- > 1.8.3.1 > >
