Hi Marc,

On 2021/1/22 19:47, Marc Zyngier wrote:
> Hi Yanan,
>
> On 2021-01-22 10:13, Yanan Wang wrote:
>> Hi, Will, Marc,
>> Is there any further comment on the v3 series I post previously?
>
> None, I was planning to queue them for 5.12 over the weekend.
>
>> If they are not fine to you, then I think maybe we should just turn
>> back to the original solution in v1, where I suggestted to filter out
>> the case of only updating access permissions in the map handler and
>> handle it right there.
>>
>> Here are the reasons for my current opinion:
>> With an errno returned from the map handler for this single case, there
>> will be one more vcpu exit from guest and we also have to consider the
>> spurious dirty pages. Besides, it seems that the EAGAIN errno has been
>> chosen specially for this case and can not be used elsewhere for other
>> reasons, as we will change this errno to zero at the end of the 
>> function.
>>
>> The v1 solution looks like more concise at last, so I refine the diff
>> and post the v4 with two patches here, just for a contrast.
>>
>> Which solution will you prefer now? Could you please let me know.
>
> I'm still very much opposed to mixing mapping and permission changes.
> How bad is the spurious return to a vcpu?
>
>
Actually, there is not much difference functionally for these two solutions.
I just thought there was a bit more change relatively in v3 for the new 
page-table framework.
But I still respect your opinion, so v3 is fine enough.  :)

Thanks,

Yanan.