Re: [kvm-devel] KVM: kvm_vcpu_block task state race

[Avi K. <av...@qu...>]

Marcelo Tosatti wrote:
>> The best practice is to issue all vcpu ioctls from the thread that 
>> created the vcpu; this becomes mandatory if we ever switch to a syscall 
>> interface and remove the mutex.
>>     
>
> For things like register dumps I don't believe its worthwhile. Much
> simpler to stop the vcpu with SIG_IPI, retrieve registers, and run it
> again (now that you mention the busy-spin, it is broken right now, if a
> vcpu is spinning without exiting to userspace).
>
> So do you want to give wait_event_interruptible() a try or wait for that
> change until userspace never issues vcpu ioctl's to a possibly busy vcpu
> (and go with the patch above)?
>   

Do we have anything critical that issues vcpu ioctls outside its 
thread?  While I much prefer wait_event_interruptible(), I don't want to 
break existing userspace.

-- 
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