Re: Postcopy migration failed with "qemu-system-x86_64: postcopy_ram_listen_thread: loadvm failed: -5"

[Dr. David Alan Gilbert]

* Kei IKEDA (s228040u@st.go.tuat.ac.jp) wrote:
> Hi!
> 
> I am experimenting with post-copy by modifying qemu-6.0.0 in my research.
> I transfer a VM between two machines but it fails most of the time with
> these error messages.
> 
> ```
> qemu-system-x86_64: postcopy_ram_listen_thread: loadvm failed: -5
> 
> 
> qemu-system-x86_64: error while loading state for instance 0x0 of device
> 'kvm-tpr-opt'
> 
> qemu-system-x86_64: load of migration failed: Operation not permitted
> ```
> 
> I checked that it does not happen in vanilla qemu-6.0.0 post-copy migration
> so my modifying causes this error.
> 
> I want to fix this error but I don't know what these error messages mean.
> 
> If anyone knows what the situation is with this error, please let me know.

My guess from that error is that the vapic_post_load function in
hw/i386/kvmvacpic.c is erroring - or something around that;  it tells
you it's the 'kvm-tpr-opt' device that's failing to load, so you need to
find out why.

Are your changes anything to do with apic?

Dave

> Thanks.
> 
> ---Experiment information---
> machine
>  HPE ProLiant DL360 Gen10
> OS
>  Linux 5.11.22 with Ubuntu 22.04.1 LTS
> Startup command
>  source side
>   ```
>   sudo /home/work/qemu-6.0.0/build/x86_64-softmmu/qemu-system-x86_64 -cpu
> host -smp 8 -m 16G -enable-kvm -drive
> if=virtio,file=/var/nfs/migrate/64G.qcow2,cache=none -monitor stdio -qmp
> tcp:localhost:4445,server,nowait -net nic -netdev
> bridge,helper=/usr/lib/qemu/qemu-bridge-helper,id=hn0 -device
> virtio-net-pci,netdev=hn0,id=br0,mac=00:16:3e:33:ad:7d -net
> user,smb=/var/nfs/migrate,hostfwd=tcp::5557-:22,hostfwd=tcp::8000-:11211
>  ```
>  destination side
>   ```
>   sudo /home/kei/work/qeme-6.0.0/build/x86_64-softmmu/qemu-system-x86_64
> -cpu host -smp 8 -m 16G -enable-kvm -drive
> if=virtio,file=/var/nfs/migrate/64G.qcow2,cache=none -monitor stdio
> -incoming tcp:0:4444 -qmp tcp:0:4446,server,nowait -net nic -netdev
> bridge,helper=/usr/lib/qemu/qemu-bridge-helper,id=hn0 -device
> virtio-net-pci,netdev=hn0,id=br0,mac=00:16:3e:33:ad:7d -net
> user,smb=/var/nfs/migrate,hostfwd=tcp::5557-:22,hostfwd=tcp::8000-:11211
>   ```
> ---------------------------------------
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK