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...

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