Re: Trying to switch EPTP for execute-protecting guest pages

[Paolo Bonzini <pbonzini@redhat.com>]

On 24/11/2015 15:51, Estrada, Zachary J wrote:
> 2) Got it. Let's say I want to work with a copy of the extended page
> tables instead of the original, what would be the best way to do so?

Why would you want that?  It's difficult to give an answer without
understanding what you're doing.  Notice that KVM pretty much always
leaves the X bit set (__direct_map uses ACC_ALL for the pte_access
parameter) so it's easy to go from your copy of the extended page tables
to the original.

I'm not sure if this is your problem, but perhaps you want to record in
the role whether the page comes from your version or the original?  The
role is like the hash key, if the role is the same you get the same PTE.

Paolo

> Right now I'm traversing the full tables using root_hpa, but if there's
> a better way using the spte interface, I would prefer that.