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

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).


Julien Grall

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