Re: [PATCH v2 5/5] KVM: MMU: retry #PF for softmmu

Xiao Guangrong
2010-11-15T09:55:25Z

On 11/15/2010 05:30 PM, Avi Kivity wrote:

>> Yeah, this 'retry' is unnecessary if the process is killed, but this
>> case is infrequent, the most case is the process keeps running and try
>> to access the fault address later.
>
> The problem is that if we retry in this case, we install an incorrect spte?
>

......

>> can avoid if the page mapping have been fixed.
>
> The guest may have changed page directories or other levels.
>

......

>> > Or another thread may have mmap()ed something else over the
>> > same address.
>>
>> The mmap virtual address is also visible for other threads since the
>> threads
>> have the same page table, so i think this case is the same as above?
>
> Again, don't we install the wrong spte in this case?
>

I think it doesn't corrupts spte since we will walk guest page table again
and map it to shadow pages when we retry #PF.