Re: [Xen-devel] PML (Page Modification Logging) design for Xen

[Tim Deegan <tim@xxxxxxx>]

At 07:08 +0000 on 12 Feb (1423721283), Tian, Kevin wrote:
> for general log dirty, ept_invalidate_emt is required because there is 
> access permission change (dirtied page becomes rw after 1st fault,
> so need to change them back to ro again for the new dirty tracking
> round). But for PML, there's no permission change at all (always rw),
> so such behavior should be noted by general logdirty layer for better
> optimization.

AIUI the reason for calling ept_invalidate_emt() is to avoid having to
update a large number of EPTEs at once.  If you still need to update a
large number of EPTEs (to clear the Dirty bits), that has to me
preemptable, or else use ept_invalidate_emt().

Or have I misunderstood?

Tim.

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