On 22/09/15 13:53, Jan Beulich wrote:
Rather than dirtying a page when establishing a (permanent) mapping,
dirty it when the page gets unmapped, or - if still mapped - on the
final iteration of a save operation (or in other cases where the guest
is paused or already shut down). (Transient mappings continue to get
dirtied upon getting mapped, to avoid the overhead of tracking.)

Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
v2: Refine predicate for calling hvm_mapped_guest_frames_mark_dirty()
     (now including all shut down domains as well as tool stack paused
     ones).

I am still convinced that it is wrong for Xen to second-guess what libxc is actually doing.

libxc should explicitly ask for the permanent mappings (or not) via another bit in a shadow op. Anything else risks not getting the bits set (so memory corruption), or having too many bits set in non-interested cases (unwanted overhead).

~Andrew

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