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Re: [Xen-devel] [PATCH 3/3 V3] XSA-60 security hole: cr0.cd handling

>>> On 30.10.13 at 16:21, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> Andrew Cooper wrote:
>> How about this:
>> 1) Clear a page with ud2s
>> 2) Use the hypervisor msr to write a new hypercall page over this
>> cleared page
>> 3) Immediately try to make a hypercall using this new page
>> What guarantee is there that Xen writing the hypercall page has made
>> its way correctly back to RAM by the time domU tries to execute the
>> hypercall? 
> Sorry, seems I didn't understand it?

He just gave you an example for what I was telling you in an
abstract way.


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