Re: [PATCH 1/2] KVM: page track: add a new notifier type: track_flush_slot

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

On 10/11/2016 02:32 AM, Paolo Bonzini wrote:
>
>
> On 10/10/2016 20:01, Neo Jia wrote:
>>> Hi Neo,
>>>
>>> AFAIK this is needed because KVMGT doesn't paravirtualize the PPGTT,
>>> while nVidia does.
>>
>> Hi Paolo and Xiaoguang,
>>
>> I am just wondering how device driver can register a notifier so he can be
>> notified for write-protected pages when writes are happening.
>
> It can't yet, but the API is ready for that.  kvm_vfio_set_group is
> currently where a struct kvm_device* and struct vfio_group* touch. Given
> a struct kvm_device*, dev->kvm provides the struct kvm to be passed to
> kvm_page_track_register_notifier.  So I guess you could add a callback
> that passes the struct kvm_device* to the mdev device.
>
> Xiaoguang and Guangrong, what were your plans?  We discussed it briefly
> at KVM Forum but I don't remember the details.
>

Your suggestion was that pass kvm fd to KVMGT via VFIO, so that we can
figure out the kvm instance based on the fd.

We got a new idea, how about search the kvm instance by mm_struct, it
can work as KVMGT is running in the vcpu context and it is much more
straightforward.