Re: [PATCH] KVM: PCIPT: VT-d support

[Avi Kivity <avi@qumranet.com>]

Muli Ben-Yehuda wrote:
> On Thu, Jul 10, 2008 at 06:07:27PM +0800, Yang, Sheng wrote:
>
>   
>> I think it's may be unnecessary to map pages when device
>> assigned. The table can be set up along with set_memory_region(), it
>> covered all memory slots already, or I miss something here?
>>     
>
> VT-d is only initialized after the slots are originally created, so
> when VT-d is initialized is map all of the existing slots separately,
> and then for each new slot that may be added we'll catch it via
> set_memory_region().
>   

It makes sense to initialize VT-d before.  Since memslots can be created 
and destroyed dynamically, with the current implementation we can see

  create slot
  create slot
  init VT-d
  create slot

which means we need to support both slot-creation-after-VT-d and 
init-VT-d-after-slot-creation.  If we initialize VT-d up front, we only 
need to support (and test) one scenario.

On the other hand, this means that you will not be able to assign 
devices unless you specified this when creating the VM; but I think this 
is fair.

-- 
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