[RFC PATCH v11 13/29] KVM: Add transparent hugepage support for dedicated guest memory

[Paolo Bonzini]

On Fri, Jul 21, 2023 at 7:13 PM Sean Christopherson <seanjc at google.com> wrote:
> On Fri, Jul 21, 2023, Paolo Bonzini wrote:
> > On 7/19/23 01:44, Sean Christopherson wrote:
> > > @@ -413,6 +454,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args)
> > >     u64 flags = args->flags;
> > >     u64 valid_flags = 0;
> > > +   if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> > > +           valid_flags |= KVM_GUEST_MEMFD_ALLOW_HUGEPAGE;
> > > +
> >
> > I think it should be always allowed.  The outcome would just be "never have
> > a hugepage" if thp is not enabled in the kernel.
>
> I don't have a strong preference.  My thinking was that userspace would probably
> rather have an explicit error, as opposed to silently running with a misconfigured
> setup.

Considering that is how madvise(MADV_HUGEPAGE) behaves, your patch is
good. I disagree but consistency is better.

Paolo