Re: [PATCH v2 08/13] s390x: protvirt: Add new VCPU reset functions

[David Hildenbrand <david@redhat.com>]

On 29.11.19 12:21, Janosch Frank wrote:
> On 11/29/19 11:47 AM, David Hildenbrand wrote:
>> On 29.11.19 10:48, Janosch Frank wrote:
>>> CPU resets for protected guests need to be done via Ultravisor
>>> calls. Hence we need a way to issue these calls for each reset.
>>>
>>> As we formerly had only one reset function and it was called for
>>> initial, as well as for the clear reset, we now need a new interface.
>>>
>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>> ---
>>>  target/s390x/cpu.c       | 14 ++++++++++++--
>>>  target/s390x/kvm-stub.c  | 10 +++++++++-
>>>  target/s390x/kvm.c       | 38 ++++++++++++++++++++++++++++++++------
>>>  target/s390x/kvm_s390x.h |  4 +++-
>>>  4 files changed, 56 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
>>> index bd39cb54b7..52fefa1586 100644
>>> --- a/target/s390x/cpu.c
>>> +++ b/target/s390x/cpu.c
>>> @@ -131,8 +131,18 @@ static void s390_cpu_reset(CPUState *s, cpu_reset_type type)
>>>      }
>>>  
>>>      /* Reset state inside the kernel that we cannot access yet from QEMU. */
>>> -    if (kvm_enabled() && type != S390_CPU_RESET_NORMAL) {
>>> -        kvm_s390_reset_vcpu(cpu);
>>> +    if (kvm_enabled()) {
>>> +        switch (type) {
>>> +        case S390_CPU_RESET_CLEAR:
>>> +            kvm_s390_reset_vcpu_clear(cpu);
>>> +            break;
>>> +        case S390_CPU_RESET_INITIAL:
>>> +            kvm_s390_reset_vcpu_initial(cpu);
>>> +            break;
>>> +        case S390_CPU_RESET_NORMAL:
>>> +            kvm_s390_reset_vcpu_normal(cpu);
>>> +            break;
>>> +        }
>>
>> I would have assumed you only have to do that for pv? For ordinary
>> guests we can avoid unnecessary ioctls IMHO.
> 
> Remember the reset normal IRQ fix in KVM?
> Without it we're not architecture compliant.

Please spell that out somewhere. People reviewing this have no idea
what's going on under the hood :)


-- 
Thanks,

David / dhildenb