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Re: [Xen-devel] [v7][RFC][PATCH 01/13] xen: RMRR fix

>>> On 29.10.14 at 01:48, <tiejun.chen@xxxxxxxxx> wrote:
> On 2014/10/28 17:34, Jan Beulich wrote:
>>>>> On 28.10.14 at 09:36, <tiejun.chen@xxxxxxxxx> wrote:
>>> On 2014/10/27 17:41, Jan Beulich wrote:
>>>>>>> On 27.10.14 at 03:00, <tiejun.chen@xxxxxxxxx> wrote:
>>>>> n 2014/10/24 18:52, Jan Beulich wrote:
>>>>>>>>> On 24.10.14 at 09:34, <tiejun.chen@xxxxxxxxx> wrote:
>>>>>>> 5. Before we take real device assignment, any access to RMRR may issue
>>>>>>> ept_handle_violation because of p2m_access_n. Then we just call
>>>>>>> update_guest_eip() to return.
>>>>>> I.e. ignore such accesses? Why?
>>>>> Yeah. This illegal access isn't allowed but its enough to ignore that
>>>>> without further protection or punishment.
>>>>> Or what procedure should be concerned here based on your opinion?
>>>> If the access is illegal, inject a fault to the guest or kill it, unless 
>>>> you
>>> Kill means we will crash domain? Seems its radical, isn't it? So I guess
>>> its better to inject a fault.
>>> But what kind of fault you prefer currently?
>> #GP (but this being arbitrary is why simply killing the guest is another
>> option to consider).
> In this case I think we just need to refer to native behavior. So I feel 
> GP may be a little bit reasonable.

But as said before - prior to switching to raising #GP, clarify for
yourself what behavior you want and why. It you properly explain
(in the patch description) why ignoring the accesses is better (read:
closer to native behavior in comparable cases), then this is fine with
me. I.e. I'm not so much questioning the solution, but the lack of
reasoning why it got chosen.


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