Re: [Xen-devel] [V7 PATCH 5/7] pvh: change xsm_add_to_physmap

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hello Mukesh,

On 30/01/14 01:33, Mukesh Rathor wrote:
> > > I'm not sure what you mean:
> > >   - the code that Mukesh is adding doesn't have a struct page, it's
> > >     just grabbing the foreign domid from the hypercall arg;
> > >   - if we did have a struct page, we'd just need to take a ref to
> > >     stop the owner changing underfoot; and
> > >   - get_pg_owner() takes a domid anyway.
> > Sorry, I was confused/mislead by the name...
> >
> > rcu_lock_live_remote_domain_by_id does look like what is needed.
Following the xentrace tread: 
http://www.gossamer-threads.com/lists/xen/devel/315883, 
rcu_lock_live_remote_domain_by_id will not correctly works.
On Xen on ARM, xentrace is using this hypercall to map XEN page (via 
DOMID_XEN). In this case, rcu_lock_*domain* will always fails which will 
prevent xentrace to works on Xen on ARM (and on PVH).
Regards,

--
Julien Grall

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