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

Avi Kivity
2010-02-10T17:08:44Z

On 02/10/2010 07:07 PM, Gleb Natapov wrote:
> 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 think only blocking syscalls and ioctls can be expected to return -EINTR.

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