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* Re: [PATCH v3 06/17] s390x: protvirt: Add migration blocker
From: Janosch Frank @ 2020-02-20 11:24 UTC (permalink / raw)
  To: Cornelia Huck; +Cc: qemu-s390x, mihajlov, qemu-devel, david
In-Reply-To: <20200220114815.01634a4c.cohuck@redhat.com>

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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?

> 
>> +        }
>> +
>>          if (s390_machine_pv_secure(ms)) {
>>              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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