Re: [PATCH 1/2] don't start cpu main loop while there is still init work to do.

[Avi Kivity <avi@redhat.com>]

Glauber Costa wrote:
> As soon as we call kvm_init_vcpu(), we start the vcpu thread.
> However, there is still things that has to be done, as soon
> as the new CPUState is created. Examples include initializing the
> apic, halting the cpu, etc.
>
> Without this patch, it is possible that the cpu may want to start
> using those things, before initializing them, leading to segfaults.
> We introduce another state variable, "initialized", meaning that
> the cpu is already created, but not totally initialized,
> to serialize it.
>
> Before this patch:
> (qemu) cpu_set X online => segfaults ~ 80 % of the time
> After this patch:
> (qemu) cpu_set X online => works.
>
>   

Is it possible to move all those things to the vcpu thread, so it 
serializes naturally?

I'd like to avoid vcpu ioctls from more than one thread, in case we ever 
move to a syscall implementation.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.