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Re: [Xen-devel] [v6][PATCH 2/2] xen:vtd: missing RMRR mapping while share EPT

>>> On 30.09.14 at 05:51, <yang.z.zhang@xxxxxxxxx> wrote:
> Jan Beulich wrote on 2014-09-25:
>>>>> On 25.09.14 at 03:53, <yang.z.zhang@xxxxxxxxx> wrote:
>>> Jan Beulich wrote on 2014-09-24:
>>>>>>> On 24.09.14 at 10:23, <yang.z.zhang@xxxxxxxxx> wrote:
>>>>> 1. RMRR region isn't reserved in guest e820 table and guest is
>>>>> able to touch it.
>>>>> Possible solution: set RMRR region as reserved in guest e820
>>>>> table and create identity map in EPT and VT-d page table.
>>>> And relocate guest RAM accordingly.
>>> ok. Let's look into more detail:
>>> 1. Whether there has device assigned or not, the RMRR mapping must
>>> be created when building e820 table if the VT-d is enabled.
> My original propose should be wrong: if there is no device attached when 
> creating guest, we should not create the identity map in guest. But I don't 
> know how to setup the EPT mapping for RMRR region in this case. Any idea?

Of course these mappings shouldn't be created blindly. There simply
shouldn't be mapped anything in these wholes, so that the identity
mappings can be put there if needed. That's why we need tool stack
awareness of these regions after all.


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