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Re: [Xen-devel] long latency of domain shutdown

To: Jan Beulich <jbeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] long latency of domain shutdown
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 28 Apr 2008 15:42:09 +0100
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On 28/4/08 15:30, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> Okay, thanks - so I indeed missed the call to hypercall_preempt_check()
> in relinquish_memory(), which is the key indicator here.
> However, that change deals exclusively with domain shutdown, but not
> with the more general page table pinning/unpinning operations, which I
> believe are (as described) vulnerable to mis-use by a malicious guest (I
> realize that well behaved guests would not normally present a heavily
> populated address space here, but it also cannot  be entirely excluded)
> - the upper bound to the number of operations on x86-64 is 512**4
> or 2**36 l1 table entries (ignoring the hypervisor hole which doesn't
> need processing).

True. It turns out to be good enough in practice though.

 -- Keir

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