Re: [PATCH v3 06/17] s390x: protvirt: Add migration blocker

[Janosch Frank <frankja@linux.ibm.com>]

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On 2/20/20 12:39 PM, Cornelia Huck wrote:
> On Thu, 20 Feb 2020 12:24:23 +0100
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> On 2/20/20 11:48 AM, Cornelia Huck wrote:
>>> On Fri, 14 Feb 2020 10:16:25 -0500
>>> Janosch Frank <frankja@linux.ibm.com> wrote:
>>>   
>>>> Migration is not yet supported.
>>>>
>>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>>> ---
>>>>  hw/s390x/s390-virtio-ccw.c | 16 ++++++++++++++++
>>>>  1 file changed, 16 insertions(+)
>>>>
>>>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>>>> index 5fa4372083..d64724af91 100644
>>>> --- a/hw/s390x/s390-virtio-ccw.c
>>>> +++ b/hw/s390x/s390-virtio-ccw.c
>>>> @@ -42,6 +42,9 @@
>>>>  #include "hw/s390x/tod.h"
>>>>  #include "sysemu/sysemu.h"
>>>>  #include "hw/s390x/pv.h"
>>>> +#include "migration/blocker.h"
>>>> +
>>>> +static Error *pv_mig_blocker;
>>>>  
>>>>  S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>>>>  {
>>>> @@ -373,6 +376,7 @@ static void s390_machine_reset(MachineState *machine)
>>>>      CPUState *cs, *t;
>>>>      S390CPU *cpu;
>>>>      S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
>>>> +    static Error *local_err;
>>>>  
>>>>      /* get the reset parameters, reset them once done */
>>>>      s390_ipl_get_reset_request(&cs, &reset_type);
>>>> @@ -422,6 +426,17 @@ static void s390_machine_reset(MachineState *machine)
>>>>          }
>>>>          run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL);
>>>>  
>>>> +        if (!pv_mig_blocker) {
>>>> +            error_setg(&pv_mig_blocker,
>>>> +                       "protected VMs are currently not migrateable.");
>>>> +        }
>>>> +        migrate_add_blocker(pv_mig_blocker, &local_err);  
>>>
>>> If I'm not lost in the context, that's during PV_RESET. I'm a bit
>>> confused why you'd add the blocker here?  
>>
>> Where would you want me to add it?
>> It's here where we switch into secure mode and I need to block before
>> switching and unblock if it fails.
>>
>> When having the blocker in diag.c, I'd have a hard time unblocking on a
>> PV switch fail.
>>
>>>   
>>>> +        if (local_err) {
>>>> +            error_report_err(local_err);
>>>> +            error_free(pv_mig_blocker);
>>>> +            exit(1);  
>>>
>>> Why the exit()? Can't you fail the call?  
>>
>> Well, if that fails and we go protected, I wouldn't be protected agains
>> migrations, right?
> 
> No, I meant not go protected, if that's possible.

That would be an option, now that we have a proper d308 rc for such a thing.

Will add!

> 
>>
>>>   
>>>> +        }
>>>> +
>>>>          if (s390_machine_pv_secure(ms)) {
> 
> Ok, I think what confuses me is this call: it reads as if you actually
> tear down things if the machine is secure. Call it
> s390_machine_pv_make_secure() to make sure it is actively doing
> something and not checking a previously set value?

Ok, will use something along these lines

> 
>>>>              CPU_FOREACH(t) {
>>>>                  s390_pv_vcpu_destroy(t);
>>>> @@ -430,6 +445,7 @@ static void s390_machine_reset(MachineState *machine)
>>>>              ms->pv = false;
>>>>  
>>>>              s390_machine_inject_pv_error(cs);
>>>> +            migrate_del_blocker(pv_mig_blocker);
>>>>              s390_cpu_set_state(S390_CPU_STATE_OPERATING, cpu);
>>>>              return;
>>>>          }  
>>>
>>>   
>>
>>
> 



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