On 2012-11-21 16:08, Christian Borntraeger wrote:
> On 21/11/12 16:06, Alexander Graf wrote:
> [...]
>>>>>>> +static int cpu_post_load(void *opaque, int version_id)
>>>>>>> +{
>>>>>>> + CPUS390XState *env = opaque;
>>>>>>> + struct kvm_fpu fpu;
>>>>>>> + int i, r;
>>>>>>> +
>>>>>>> + if (!kvm_enabled()) {
>>>>>>> + return 0;
>>>>>>> + }
>>>>>>> +
>>>>>>> + for (i = 0; i< 16; i++) {
>>>>>>> + fpu.fprs[i] = env->fregs[i].ll;
>>>>>>> + }
>>>>>>> + fpu.fpc = env->fpc;
>>>>>>> +
>>>>>>> + r = kvm_vcpu_ioctl(env, KVM_SET_FPU,&fpu);
>>>>>>> + assert(r == 0);
>>>>>>> +
>>>>>>> + return 0;
>>>>>>> +}
>>>>>> The kvm register sync needs to happen in the kvm register sync function
>>>>>> :)
>>>>> That would eliminate the whole purpose of sync regs and forces us to have
>>>>> an
>>>>> expensive ioctl on lots of exits (again). I would prefer to sync the
>>>>> registers
>>>>> that we never need in qemu just here.
>>>> That's why the register sync has different stages.
>>> Not the get_register. Which is called on every synchronize_state. Which
>>> happen quite often
>>> on s390.
>>
>> Sounds like bad design then :).
>>
>> Maybe we should explicitly tell the register synchronization which register
>> sets to sync, so that we don't waste time getting _all_ the state every time
>> we sync registers?
>
> Yes, a level statement for kvm_arch_get_registers would be good.
>
The challenge is defining those levels generically - as it is also
generic code that calls cpu_synchronize_state. What levels do you have
in mind? And where would they be applied?
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
