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

[Tim Deegan <tim@xxxxxxx>]

At 05:43 +0000 on 10 Apr (1428644619), Zhang, Yang Z wrote:
> 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.

Any progress?  AFAICT nested VMX is not safe to use until this is
fixed.

Tim.

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