Il 16/09/2014 17:55, Marcelo Tosatti ha scritto: > On Tue, Sep 16, 2014 at 05:42:16PM +0200, Paolo Bonzini wrote: >> Il 16/09/2014 17:14, Marcelo Tosatti ha scritto: >>> + /* >>> + * Make sure that CPU state is synchronized from KVM >>> + * once every VM state change callback has finished. >> >> Which other callback could affect the in-kernel state, > > Marcin mentioned that APIC state was the culprit. > > Perhaps > > bdrv_drain_all(); > ret = bdrv_flush_all(); > > Can change the interrupt state ?
Ah, I thought Marcin was checking on the destination, not the source. > Then that should read "once VM stop has finished". But I still do not understand. The cpu_synchronize_all_states() call in kvmclock_vm_state_change() is needed to make env->tsc up to date with the value on the source, right? But if the synchronize_all_states+clean_all_dirty pair runs on the source, why is the cpu_synchronize_all_states() call in qemu_savevm_state_complete() not enough? It runs even later than kvmclock_vm_state_change. I don't understand even the original patch without cpu_clean_all_dirty()... Paolo
