Re: [Qemu-devel] [PATCH v1 for-2.12 2/2] s390x: load_psw() should only exchange the PSW for KVM

[Christian Borntraeger]

On 04/09/2018 01:44 PM, David Hildenbrand wrote:
> On 09.04.2018 13:40, Christian Borntraeger wrote:
>>
>>
>> On 04/09/2018 01:36 PM, David Hildenbrand wrote:
>>> On 09.04.2018 13:35, Christian Borntraeger wrote:
>>>>
>>>>
>>>> On 04/09/2018 01:30 PM, David Hildenbrand wrote:
>>>>> Let's simplify it a bit. On some weird circumstances we would have tried
>>>>> to recompute watchpoints when running under KVM.
> 
> 
> 
>>>>>
>>>>> Signed-off-by: David Hildenbrand <address@hidden>
>>>>> ---
>>>>>  target/s390x/helper.c | 10 ++++++----
>>>>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>>>>
>>>>> diff --git a/target/s390x/helper.c b/target/s390x/helper.c
>>>>> index 615fa24ab9..e8548f340a 100644
>>>>> --- a/target/s390x/helper.c
>>>>> +++ b/target/s390x/helper.c
>>>>> @@ -103,16 +103,18 @@ void load_psw(CPUS390XState *env, uint64_t mask, 
>>>>> uint64_t addr)
>>>>>
>>>>>      env->psw.addr = addr;
>>>>>      env->psw.mask = mask;
>>>>> -    if (tcg_enabled()) {
>>>>> -        env->cc_op = (mask >> 44) & 3;
>>>>> +
>>>>> +    /* KVM will handle all WAITs and trigger a WAIT exit on 
>>>>> disabled_wait */
>>>>> +    if (!tcg_enabled()) {
>>>>> +        return;
>>>>>      }
>>>>> +    env->cc_op = (mask >> 44) & 3;
>>>>
>>>> Do we have any call path were KVM could call load_psw?
>>>
>>> do_restart_interrupt()
>>>
>>> SIGP while the target CPU is stopped.
>>
>> makes sense. Can you add that to the patch description? that makes it easier 
>> to understand
>> what can really go wrong without this patch.
> 
> Sure!
> 
> Conny, when (and if ;) ) picking this up, can you change the description to
> 
> "Let's simplify it a bit. On some weird circumstances we would have
> tried to recompute watchpoints when running under KVM. load_psw() is
> called from do_restart_interrupt() during a SIGP RESTART if the target
> CPU is STOPPED. Let's touch watchpoints only in the TCG case - where
> they are used for PER emulation."
> 
With that:

Acked-by: Christian Borntraeger <address@hidden>