Re: [Xen-devel] [PATCH] VMX: wbinvd when vmentry under UC

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Andrew Cooper wrote:
> On 29/11/13 14:15, Liu, Jinsong wrote:
>> Jan Beulich wrote:
>>>>>> "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> 11/28/13 8:17 AM >>>
>>>> Liu, Jinsong wrote:
>>>>> Yes. reprogram_timer here just delay timer a little slot, say,
>>>>> 1~2ms. I think it's OK, i.e. at any point of wbinvd() operation at
>>>>> hypervisor, or any irq disabled area, timer interrupt in fact also
>>>>> has good chance to be delayed some time -- however at
>>>>> TIMER_SOFTIRQ, all expired thing would be executed, and
>>>>> re-calculated and set next time point via reprogram_timer --
>>>>> that's OK. 
>>>> Comments/thoughts about this option?
>>> Apart from continuing to be very uncertain that this won't have any
>>> bad side effects, I'm also rather concerned that you deal with one
>>> special case interrupt here, ignoring other potentially high rate
>>> ones (like such coming from NICs). 
>>> 
>>> Jan
>> Considering this, seems adding flag is the only work around way
>> since high freq interrupt would result in dead-like-loop. My concern
>> of adding flag is it's not easy to clean every possible path,
>> especially future extension.   
>> 
>> Or, do not support vt-d w/o snoop.
>> 
>> Thanks,
>> Jinsong
> 
> Do you know how many systems have vt-d without snoop ?
> 
> ~Andrew

Yes, that's what I need check inside Intel. Maybe not feasible idea I agree.

Thanks,
Jinsong
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