Re: [Xen-devel] [PATCH 1 of 7] Make p2m lookups fully synchronized wrt modifications

[Tim Deegan <tim@xxxxxxx>]

At 00:45 -0500 on 09 Feb (1328748346), Andres Lagar-Cavilla wrote:
> We achieve this by locking/unlocking the global p2m_lock in get/put_gfn.
> 
> The lock is always taken recursively, as there are many paths that
> call get_gfn, and later, make another attempt at grabbing the p2m_lock.
> 
> The lock is not taken for shadow lookups. We believe there are no problems
> remaining for synchronized p2m+shadow paging, but we are not enabling this
> combination due to lack of testing. Unlocked shadow p2m access are tolerable 
> as
> long as shadows do not gain support for paging or sharing.
> 
> HAP (EPT) lookups and all modifications do take the lock.
> 
> Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>

Acked-by: Tim Deegan <tim@xxxxxxx>

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