On Fri, 24 Jul 2026 09:10:49 -0400
Matthew Rosato <[email protected]> wrote:

> On 7/13/26 11:52 AM, Claudio Imbrenda wrote:
> > Allow mapping guest with 2G hugepages on hosts that support it.
> > 
> > Signed-off-by: Claudio Imbrenda <[email protected]>
> > ---
> >  target/s390x/kvm/kvm.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> > index 72031a5714..23fa714b69 100644
> > --- a/target/s390x/kvm/kvm.c
> > +++ b/target/s390x/kvm/kvm.c
> > @@ -298,13 +298,13 @@ void kvm_s390_set_max_pagesize(uint64_t pagesize, 
> > Error **errp)
> >          return;
> >      }
> >  
> > -    if (pagesize != 1 * MiB) {
> > +    if ((pagesize == 2 * GiB) &&
> > +        kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_2G, 0)) {
> >          error_setg(errp, "Memory backing with 2G pages was specified, "
> >                     "but KVM does not support this memory backing");
> >          return;
> > -    }
> > -
> > -    if (kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_1M, 0)) {
> > +    } else if ((pagesize == MiB) &&
> > +               kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_HPAGE_1M, 0)) {
> >          error_setg(errp, "Memory backing with 1M pages was specified, "
> >                     "but KVM does not support this memory backing");
> >          return;  
> 
> Just double-checking -- If you successfully take the 2G path here you
> will still set cap_hpage_1m = 1;
> 
> I suspect it's intentional to fence diag 308?  But then IMO

I was more thinking of cmma and similar, but yes it's intentional

> 
> s/kvm_s390_get_hpage_1m/kvm_s390_get_hpage/
> and
> s/ cap_hpage_1m/ cap_hpage_any/
> or something like that

Yeah, makes sense. I wanted to keep my changes minimal, hence why I
left the old names.




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