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

[Tim Deegan <tim@xxxxxxx>]

At 09:47 +0100 on 23 Apr (1429782448), Tim Deegan wrote:
> 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.

Ping...

Tim.

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