Re: About two-dimensional page translation (e.g., Intel EPT) and shadow page table in Linux QEMU/KVM

[Maxim Levitsky]

On Mon, 2021-07-12 at 08:02 -0500, harry harry wrote:
> Dear Maxim,
> 
> Thanks for your reply. I knew, in our current design/implementation,
> EPT/NPT is enabled by a module param. I think it is possible to modify
> the QEMU/KVM code to let it support EPT/NPT and show page table (SPT)
> simultaneously (e.g., for an 80-core server, 40 cores use EPT/NPT and
> the other 40 cores use SPT). What do you think? Thanks!
> 
> Best regards,
> Harry
> 
> On Mon, Jul 12, 2021 at 4:49 AM Maxim Levitsky <mlevitsk@redhat.com> wrote:
> > On Sun, 2021-07-11 at 15:13 -0500, harry harry wrote:
> > > Hi all,
> > > 
> > > I hope you are very well! May I know whether it is possible to enable
> > > two-dimensional page translation (e.g., Intel EPT) mechanisms and
> > > shadow page table mechanisms in Linux QEMU/KVM at the same time on a
> > > physical server? For example, if the physical server has 80 cores, is
> > > it possible to let 40 cores use Intel EPT mechanisms for page
> > > translation and the other 40 cores use shadow page table mechanisms?
> > > Thanks!
> > 
> > Nope sadly. EPT/NPT is enabled by a module param.
> > 
> > Best regards,
> >         Maxim Levitsky
> > 
> > > Best,
> > > Harry
> > > 
For same VM, I don't think it is feasable.

For multiple VMs make some use NPT/EPT and some don't,
this should be possible to implement.

Why do you need it?

Best regards,
        Maxim Levitsky