Re: [Xen-devel] [RFC PATCH] PVH: cleanup of p2m upon p2m destroy

[Tim Deegan <tim@xxxxxxx>]

At 11:09 +0100 on 18 Dec (1387361398), Tim Deegan wrote:
> > An alternative might be to just create a link list then and walk it. In
> > general, foreign mappings should be very small, so the overhead of
> > 16 bytes per page for the link list might not be too bad. I will code
> > it if there is no disagreement from any maintainer... everyone has 
> > different ideas :)...
> 
> I think it would be best to walk the p2m trie (i.e. bounded by amount
> of RAM, rather than max GFN) and do it preemptably.  I'll look into
> something like that for the mem_sharing loop today, and foreign
> mapping code can reuse it.

What I've ended up with is making p2m_change_entry_type_global()
preemptible (which is a bigger task but will be needed as domains get
bigger).  Do you think that using that function to switch all mappings
from p2m_foreign to p2m_invalid, appropriately late in the teardown,
will be good enough for what you need?

Cheers,

Tim.

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