Re: [PATCH v1 3/4] KVM: MMU: Add 5 level EPT & Shadow page table support.

[Yu Zhang]

On 8/14/2017 11:02 PM, Paolo Bonzini wrote:
> On 14/08/2017 16:32, Yu Zhang wrote:
> > On 8/14/2017 10:13 PM, Paolo Bonzini wrote:
> > > On 14/08/2017 13:37, Yu Zhang wrote:
> > > > Thanks a lot for your comments, Paolo. :-)
> > > >
> > > >
> > > > On 8/14/2017 3:31 PM, Paolo Bonzini wrote:
> > > > > On 12/08/2017 15:35, Yu Zhang wrote:
> > > > > >     struct rsvd_bits_validate {
> > > > > > -    u64 rsvd_bits_mask[2][4];
> > > > > > +    u64 rsvd_bits_mask[2][5];
> > > > > >         u64 bad_mt_xwr;
> > > > > >     };
> > > > > Can you change this 4 to PT64_ROOT_MAX_LEVEL in patch 2?
> > > > Well, I had tried, but failed to find a neat approach to do so. The
> > > > difficulty I have met is that PT64_ROOT_MAX_LEVEL is defined together
> > > > with PT64_ROOT_4LEVEL/PT32E_ROOT_LEVEL/PT32_ROOT_LEVEL in mmu.h, yet
> > > > the rsvd_bits_validate structure is defined in kvm_host.h, which are
> > > > included in quite a lot .c files that do not include mmu.h or include
> > > > the mmu.h after kvm_host.h.
> > > >
> > > > I guess that's the reason why the magic number 4 instead of
> > > > PT64_ROOT_4LEVEL is used in current definition of
> > > > rsvd_bits_vadlidate. :-)
> > > Yes, you're right.  I think the solution is to define
> > > PT64_ROOT_MAX_LEVEL in kvm_host.h.
> > Thanks, Paolo. How about we also move the definition of PT64_ROOT_4LEVEL/
> > PT32E_ROOT_LEVEL/PT32_ROOT_LEVEL from mmu.h to kvm_host.h? Then we
> > can define PT64_ROOT_MAX_LEVEL as PT64_ROOT_4LEVEL instead of 4 in
> > kvm_host.h.
> No, I think those are best left in mmu.h.  They are only used in mmu
> files, except for two occurrences in svm.c.
>
> kvm_host.h would have PT64_ROOT_MAX_LEVEL just because it is slightly
> better than "4" or "5".

OK. I can define PT64_ROOT_MAX_LEVEL in kvm_host.h as 4 in patch 2, and 
change
it to 5 in patch 3. :- )

Thanks
Yu