Re: [Xen-devel] [PATCH V4] X86/vMCE: handle broken page with regard to migration

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

Ian Campbell wrote:
> (please trim your quotes)
> 
>> More simply, we can remove not only step #8 for last iteration check,
>> but also the action to 'mark broken page to dirty bitmap':
>> In any iteration, there is a key point #4, if vmce occur before #4 it
>> will transfer proper pfn_type/pfn_number and (xl migration) will not
>> access broken page (if guest access the broken page again it will be
>> killed by hypervisor), if vmce occur after #4 system will crash and
>> no need care migration any more. 
>> 
>> So we can go back to the original patch which used to handle 'vmce
>> occur before migration' and entirely don't need add specific code to
>> handle 'vmce occur during migration', since it in fact has handled
>> both cases (and simple). Thoughts?
> 
> Do you not need that stuff to handle MCEs during the live phase?
> 
> Specifically an MCE occurring on a page which is not in the current
> batch at all can be handled safely during the live phase.
> 
> Ian.

No, we don't need care it. Whether a page (mce occurred at) is in current batch 
or not is not important:
1. if xl will not transfer it in the future, that's fine;
2. if xl will transfer it in the future, but it was not in current batch, 
that's also fine --> it will be handled at its batch;
(guest will be killed if it access the broken page again)

Thanks,
Jinsong
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