There are more debug messages but these seem like the most relevant.
Apr 3 20:02:18 localhost xapi: [debug||1864 ||vgpuops] vGPUs allocated to VM (OpaqueRef:ee6254af-44af-4bcf-8382-d9b7542d2b3c) are:
Apr 3 20:02:56 localhost xapi: [ warn||1864 ||rbac_audit] cannot marshall arguments for the action VM.migrate_send: name and value list lengths don't match. str_names=[session_id,vm,dest,live,vdi_map,vif_map,options,vgpu_map,], xml_values=[S(OpaqueRef:4489cc5b-fbe9-44d4-a60f-627b8960338f),S(OpaqueRef:ee6254af-44af-4bcf-8382-d9b7542d2b3c),{SM:S(http://10.100.10.31/services/SM?session_id=OpaqueRef:cd0a7342-5155-434d-a8ca-2e9f7dcf8460);host:S(OpaqueRef:ac2e50bc-1f80-417a-8eea-a7ce955d4c24);xenops:S(http://10.100.10.31/services/xenops?session_id=OpaqueRef:cd0a7342-5155-434d-a8ca-2e9f7dcf8460);session_id:S(OpaqueRef:cd0a7342-5155-434d-a8ca-2e9f7dcf8460);master:S(http://10.100.10.31/)},B(true),{OpaqueRef:a4398d4e-946c-4c83-ad5f-b4dc1c3ddeee:S(OpaqueRef:4c00dfd9-a30c-47a4-8367-e8a7d7c53cb6);OpaqueRef:188682c3-1b45-4ae4-98cf-0dfff1d90d56:S(OpaqueRef:4c00dfd9-a30c-47a4-8367-e8a7d7c53cb6)},{},{force:S(false)},]