Re: [Qemu-devel] latest rc: virtio-blk hangs forever after migration

["Marcin Gibuła" <m.gibula@beyond.pl>]

On 29.07.2014 18:58, Paolo Bonzini wrote:
> Il 18/07/2014 10:48, Paolo Bonzini ha scritto:
>>
>> It is easy to find out if the "fix" is related to 1 or 2/3: just write
>>
>>       if (cpu->kvm_vcpu_dirty) {
>>           printf ("do_kvm_cpu_synchronize_state_always: look at 2/3\n");
>>           kvm_arch_get_registers(cpu);
>>       } else {
>>           printf ("do_kvm_cpu_synchronize_state_always: look at 1\n");
>>       }
>>
>> To further refine between 2 and 3, I suppose you can set a breakpoint on
>> cpu_synchronize_all_states and kvm_cpu_exec, and see which is called
>> first after cpu_synchronize_all_states_always.
>
> Marcin, have you ever gotten round to doing this?

Source side of migration, without my ugly hack:

called do_kvm_cpu_synchronize_state: vcpu not dirty, getting registers
called do_kvm_cpu_synchronize_state: vcpu not dirty, getting registers
called kvm_cpu_synchronize_state: vcpu dirty
called kvm_cpu_synchronize_state: vcpu dirty
shutting down

without it:

called do_kvm_cpu_synchronize_state_always
called do_kvm_cpu_synchronize_state_always
called do_kvm_cpu_synchronize_state: vcpu not dirty, getting registers
called do_kvm_cpu_synchronize_state: vcpu not dirty, getting registers
shutting down

So it's probably about 2 from your list ("the next call to 
do_kvm_cpu_synchronize_state will do kvm_arch_get_registers").

I've tapped into kvm_cpu_exec() to find out if it's 
kvm_arch_put_registers(), but nothing was logged during migration so 
it's probably not 3.

-- 
mg