Re: [RFC PATCH v4 0/2] Some optimization for stage-2 translation

[Marc Zyngier]

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?

Thanks,

        M.
--
Jazz is not dead. It just smells funny...