Re: qemu-kvm: do not allow vcpu stop with in progress PIO

Alexander Graf
2010-02-10T17:03:43Z

Avi Kivity wrote:
> On 02/10/2010 06:52 PM, Alexander Graf wrote:
>>
>> Hrm, trying to read the thread I'm still somewhat lost. What exactly do
>> you want to document?
>>
>>
>
> The problem: if KVM_RUN exits with KVM_EXIT_MMIO or KVM_EXIT_IO, then
> the internal state is inconsistent. The instruction is only half
> completed, and we need to reissue KVM_RUN to complete it.
>
> However, if we're migrating, then we don't want to execute any more
> guest code. Luckily, if you KVM_RUN with a pending signal, then the
> pending mmio or io will be completed, and then, if the pending signal
> is unmasked in kvm's signal mask, KVM_RUN will exit immediately.
>
> I would like to document the fact that the signal check happens
> between the mmio completion and guest entry, and the above sequence as
> a way to get consistent state after mmio.
>

I see. Yes, that works for PPC Book3S too. We check for signals on the
beginning of vcpu_run. I'm not sure about BookE though.

Either way - wouldn't it make more sense to just move the check to
generic code?

Alex