Re: [Xen-devel] [PATCH] Make get_page_from_l1e refcount correctly onforeign pagetables.

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 14/05/2009 09:22, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:

>> Perhaps the whole thing gets more convoluted because of c/s 19383, which
>> added a vcpu parameter for no apparent reason (current is used for that
>> everywhere afaict).
> 
> That parameter is used so that dom0 can modify a PV domU's pagetables
> using the MMU ops (so dom0 tools can offline a suspect page without
> domU's help).  In that case, I think the current patch actually fixes a
> latent bug in refcounting foreign mappings from the target domU to a
> third (HVM) domain, that was missed in cs 19383.
> 
> This is all pretty confusing, though, and Keir may correct me on any or
> all of it. :)

I wish I could. I need a damp towel wrapped round my head to understand the
details of that code now. We may need to step back and refactor and rethink
after 3.4. Hence my reluctance to mess with it now, as I fear introducing
bugs more significant than latent stubdom issues.

 -- Keir



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