Re: [Xen-devel] [PATCH] x86/p2m: Stop other vcpus using a nested p2m before clearing it

[Tim Deegan <tim@xxxxxxx>]

At 18:48 +0000 on 07 Feb (1486493293), Andrew Cooper wrote:
> Until the IPI has completed, other processors might be running on this nested
> p2m object.  clear_domain_page() does not guarantee to make 8-byte atomic
> updates, which means that a pagewalk on a remote processor might encounter a
> partial update.
> 
> This is currently safe as other issues prevents a nested p2m ever being shared
> between two cpus (although this is contrary to the original plan).
> 
> Setting p2m->np2m_base to P2M_BASE_EADDR before the IPI ensures that the IPI'd
> processors won't continue to use the flushed mappings.
> 
> While modifying this function, remove all the trailing whitespace and tweak
> style in the affected areas.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Tim Deegan <tim@xxxxxxx>

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