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

Gleb Natapov
2010-02-10T17:07:52Z

On Wed, Feb 10, 2010 at 07:01:46PM +0200, 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.
>
Can we be sure that pending signal checking will not be introduces
somewhere in ioctl generic code before kvm specific code is called?

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

--
Gleb.