Re: [PATCH v4 24/27] KVM: s390: arm64: Implement vm/vcpu create destroy.

[Marc Zyngier]

On Wed, 08 Jul 2026 07:51:50 +0100,
Steffen Eiden <seiden@xxxxxxxxxxxxx> wrote:
> 
> On Tue, Jul 07, 2026 at 04:10:19PM +0100, Marc Zyngier wrote:
> > On Mon, 06 Jul 2026 09:52:24 +0100,
> > Steffen Eiden <seiden@xxxxxxxxxxxxx> wrote:
> > > 
> > > Implement init and destroy IOCTLS for vcpu and vm.
> > > Implement arch vm IOCTL. Use s390 gmap.
> > > 
> > > Co-developed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > > Co-developed-by: Andreas Grapentin <gra@xxxxxxxxxxxxx>
> > > Signed-off-by: Andreas Grapentin <gra@xxxxxxxxxxxxx>
> > > Co-developed-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
> > > Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
> > > Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
> > > ---
> > >  arch/s390/kvm/arm64/arm.c       | 190 ++++++++++++++++++++++++++++++++
> > >  arch/s390/kvm/arm64/arm.h       |  56 ++++++++++
> > >  arch/s390/kvm/gmap/faultin.c    |   5 +
> > >  arch/s390/kvm/gmap/gmap.c       |   4 +
> > >  arch/s390/kvm/gmap/trace-gmap.h |  13 +++
> > >  5 files changed, 268 insertions(+)
> > > 
> > > diff --git a/arch/s390/kvm/arm64/arm.c b/arch/s390/kvm/arm64/arm.c
> > > index 19249ec5c539..3a4092698fae 100644
> > > --- a/arch/s390/kvm/arm64/arm.c
> > > +++ b/arch/s390/kvm/arm64/arm.c
> > > @@ -8,6 +8,10 @@
> > >  #include <linux/kvm_types.h>
> > >  #include <linux/kvm_host.h>
> > >  
> > > +#include <arm64/kvm_mmu.h>
> > > +
> > > +#include <gmap.h>
> > > +
> > >  #include "arm.h"
> > >  
> > >  static unsigned long system_supported_vcpu_features(void);
> > > @@ -31,6 +35,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> > >  		break;
> > >  	case KVM_CAP_IOEVENTFD:
> > >  	case KVM_CAP_ARM_USER_IRQ:
> > > +	case KVM_CAP_PRE_FAULT_MEMORY:
> > 
> > arm64 *doesn't* support this yet. Please make sure you don't deviate
> > from what arm64 currently supports.
> >
> 
> I hoped the corresponding arm64 series is merged when we got this :) 

If the quality of the previous postings of that series is anything to
go by, I doubt this will be merged on this side of the death of the
universe.

> I will remove this advertisement. I'll keep the implementation as the compiler
> expect that function to be present anyways, as native s390 KVM now implements
> this CAP. OK? 

As long as the code isn't reachable from the arm64 side, that's fine
by me.

	M.

-- 
Without deviation from the norm, progress is not possible.