Re: [Xen-devel] [Qemu-devel] [PATCH] x86: Skip check apic_id_limit for Xen

[Lan Tianyu <tianyu.lan@xxxxxxxxx>]

On 2017年10月26日 22:27, Michael S. Tsirkin wrote:
> On Thu, Oct 26, 2017 at 02:19:43PM +0200, Eduardo Habkost wrote:
>> On Mon, Aug 21, 2017 at 10:22:15AM +0800, Lan Tianyu wrote:
>>> On 2017年08月19日 00:38, Eduardo Habkost wrote:
>>>> On Thu, Aug 17, 2017 at 09:37:10AM +0800, Lan Tianyu wrote:
>>>>> On 2017年08月16日 19:21, Paolo Bonzini wrote:
>>>>>> On 16/08/2017 02:22, Lan Tianyu wrote:
>>>>>>> Xen vIOMMU device model will be in Xen hypervisor. Skip vIOMMU
>>>>>>> check for Xen here when vcpu number is more than 255.
>>>>>>
>>>>>> I think you still need to do a check for vIOMMU being enabled.
>>>>>
>>>>> Yes, this will be done in the Xen tool stack and Qemu doesn't have such
>>>>> knowledge. Operations of create, destroy Xen vIOMMU will be done in the
>>>>> Xen tool stack.
>>>>
>>>> Shouldn't we make QEMU have knowledge of the vIOMMU device, then?
>>>> Won't QEMU need to know about it eventually?
>>>>
>>>
>>> Hi Eduardo:
>>>      Thanks for your review.
>>>      Xen has some guest modes which doesn't use Qemu and we tried to
>>> make Xen vIOMMU framework compatible with all guest modes. So far, we
>>> are adding interrupt remapping function for Xen vIOMMU and find qemu
>>> doesn't need to know Xen vIOMMU. The check of vcpu number > 255 here
>>> will be done in Xen side and so skip the check in Qemu to avoid blocking
>>> Xen creating >255 vcpus.
>>>      We may make Qemu have knowledge of the vIOMMU device if it's
>>> necessary when adding new function.
>>
>> I was expecting it to go through the PC tree, but I will queue it
>> on x86-next instead.
> 
> I was waiting for an ack from you or Paolo as you participated in the
> discussion. But sure, go ahead
> 
> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> 

Great. Thanks.
-- 
Best regards
Tianyu Lan

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