Re: kernel device reset support

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Avi Kivity wrote:
>>>     
>>>       
>> For a graceful reboot, this one is not needed since every APs are
>> already brought to HALT status before BSP issue RESET signal. But in
>> case of non-graceful reboot, it is possible the VCPUs are still
>> executing guest instruction, so we kick the VCPU and then use this logic
>> to force the exception handler to be a heavy VM Exit and execute
>> following code at beginning of kvm_vcpu_ioctl_run. (Let
>> VCPU_MP_STATE_UNINITIALIZED take effective)
>>
>>         if (unlikely(vcpu->mp_state == VCPU_MP_STATE_UNINITIALIZED)) {
>>                 if (irqchip_in_kernel(vcpu->kvm) && vcpu->apic)
>>                         kvm_lapic_reset(vcpu);
>>                 kvm_vcpu_block(vcpu);
>>                 vcpu_put(vcpu);
>>                 return -EAGAIN;
>>         }
>>
>> Whether we need to handle those un-graceful reboot case is up to you :-)
>> If not, then those code can be removed.
>>   
>>     
>
> We do need to support ungraceful resets.  But this could easily be done 
> via vcpu->requests.
>
> To reset a vcpu:
>
>     set_bit(KVM_REQ_RESET, &vcpu->requests)
>     kvm_vcpu_kick(vcpu);
>
> And in __vcpu_run():
>
>    if (vcpu_requests) {
>          if (test_and_reset_bit(KVM_REQ_RESET, &vcpu->requests))
>             ....
>    }
>
>   


To be clear, you can move the reset call to that location ("...") and 
avoid the need to take a heavyweight exit completely.

-- 
error compiling committee.c: too many arguments to function


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