Re: [Xen-devel] [PATCH 3/3] x86/mm-locks: apply a bias to lock levels for current domain

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.12.18 at 15:07, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 19/12/2018 13:55, George Dunlap wrote:
>> Yes, if someone uses XSM to bypass the IS_PRIV() functionality to give
>> one domain access over another, then the lock checking will trigger.
> 
> Noone should be able to trigger assertions in the hypervisor by simply
> editing the XSM policy.
> 
> This quite clearly demonstrates that the proposed logic isn't appropriate.

You could view it the other way around: Anyone who writes an
XSM policy violating assumptions in the hypervisor is shooting
themselves in the foot (read: introduces a bug). In particular I
don't think something like fuzzed XSM policies would make any
sense (which is no different to someone making random edits).

Jan



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