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Xen Memory Sharing Query
- To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Marc Bonnici <Marc.Bonnici@xxxxxxx>
- Date: Fri, 15 Jul 2022 15:56:46 +0000
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- Delivery-date: Fri, 15 Jul 2022 15:57:13 +0000
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- Thread-topic: Xen Memory Sharing Query
Hi All,
I was wondering if someone could help me understand some of the rules of the
memory sharing implementation in Xen?
Specifically I'm looking to understand what restrictions Xen places on
granting access from one Dom to another from Xen's perspective, and what types
of grant requests would be allowed/rejected by Xen?
I.e. How would the situation be handled if the same frame of memory was
attempted
to be shared multiple times?
As an example scenario, DomA shares 1 physical page of memory in a transaction
with DomB. And then without releasing any memory, DomA attempts to share
another region of memory, which includes the same physical page of the previous
share
with DomB again. This would result in two concurrent shares containing an
overlap.
Apologies if I've missed something but is there any documentation / threat model
that would cover these types of scenarios? So far I have been trying to read
through
the code but was wondering if there is something else I could refer to help me
with my understanding?
Thanks
Kind Regards,
Marc Bonnici
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