Re: [Xen-devel] Nested EPT flushes on p2m change?

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Tian, Kevin wrote on 2015-04-03:
>> From: Tim Deegan [mailto:tim@xxxxxxx]
>> Sent: Thursday, March 26, 2015 7:10 PM
>> 
>> Hi, VMX maintainers,
>> 
>> I was looking at the nested EPT code while following up on Ed's
>> email about altp2m design, and I can't see where nested-EPT entries
>> get removed when a host EPT entry is removed/changed.
>> 
>> On nested NPT, this is handled in hap_write_p2m_entry(), which
>> detects that the domain has nested p2ms and calls
>> p2m_flush_nestedp2m() if necessary.
>> 
>> But nested EPT doesn't use the ->write_p2m_entry() hook to update
>> entries, it uses atomic_write_ept_entry() instead.  AFAICS the only
>> flushing done on that path is ept_sync_domain(), which doesn't do
>> anything about nested p2ms.
>> 
>> Am I forgetting something?

It looks like you are right. The original nested EPT doesn't consider it. 

CC Xiantao who is the author of the nested EPT.

>> 
> 
> Add Yang who understands that detail better than me. :-)
> 
> Thanks
> Kevin


Best regards,
Yang


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