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

["Chen, Tiejun" <tiejun.chen@intel.com>]

On 2014/7/30 18:47, Jan Beulich wrote:
>>>> On 30.07.14 at 12:40, <tiejun.chen@intel.com> wrote:
>> On 2014/7/30 18:25, Jan Beulich wrote:
>>>>>> On 30.07.14 at 11:40, <tiejun.chen@intel.com> wrote:
>>>>    From what those codes mean, it just return regardless whether they
>>>> really conflict. And this is just a good assumption, so if I'm
>>>> understanding this properly, actually our patches do this thing
>>>> precisely because we further check if this assumption is true, then take
>>>> necessary actions.
>>>
>>> Except that the pointed out check prevents the code you modify
>>> from being reached at all, i.e. as long as that check is there it
>>> doesn't matter (for any passed through USB device) what action
>>> rmrr_identity_mapping() takes.
>>>
>>
>> Sorry, what do you mean?
>>
>>   From my point of view these two patches should be better than drop
>> simply RMRR for any PT USB device no matter if its really necessary.
>
> I mean that for USB devices your patches change nothing without
> said check also getting removed.
>

Jan,

For USB instance, I think currently we still keep that until we have a 
complete solution since this is always safe.

Additionally, I'm trying to figure out that solution. As I mentioned 
previously, I think we can reserve all RMRR once when a guest call 
XENMEM_machine_memory_map to create its own memory. What about this 
idea? Or other better suggestions?

Thanks
Tiejun