migrate from qemu 2.11 to qemu 4.2 failed on arm machine

[Jiatong Shen]

Hello community experts,

   I am facing an issue to migrate a virtual machine from qemu 2.11 to qemu 4.2 node. The command using on src node is

qemu-system-aarch64 -M virt -vnc :2 -rtc base=utc,driftfix=slew -smp 2 -m 4096 -cpu host -enable-kvm -nodefaults -incoming :4443

on the dst node, the command is 

qemu-system-aarch64 -M virt-2.11 -enable-kvm -cpu host -smp 2 -m 4096 -incoming tcp::4443 -rtc base=utc,driftfix=slew -nodefaults  

after running migrate tcp:localhost:4443, the dest machine failed with following message

Segmentation fault (core dumped)

I try to debug and find the following trace: 0x0000aaab0f07262c in armv7m_nvic_neg_prio_requested (opaque=0x0, secure=false) at /root/qemu-4.2.1/hw/intc/armv7m_nvic.c:391.

After some investigation, I believe the issue is from https://elixir.bootlin.com/qemu/v4.2.1/source/target/arm/helper.c#L11134 and ARM_FEATURE_M 's value is changed from 2.11 to 4.2.

My question is do we support migrating from 2.11 to 4.2  on aarch64 platform? Thank you much for the help

--

Best Regards,

Jiatong Shen