Re: [PATCH v14 27/44] arm64: RMI: Set RIPAS of initial memslots

[Suzuki K Poulose]

On 19/05/2026 11:02, Aneesh Kumar K.V wrote:
> Steven Price <steven.price@xxxxxxx> writes:
>
> > The memory which the realm guest accesses must be set to RIPAS_RAM.
> > Iterate over the memslots and set all gmem memslots to RIPAS_RAM.
> >
> > Signed-off-by: Steven Price <steven.price@xxxxxxx>
> > ---
>   
>   ...
>   
> > +static int set_ripas_of_protected_regions(struct kvm *kvm)
> > +{
> > +	struct kvm_memslots *slots;
> > +	struct kvm_memory_slot *memslot;
> > +	int idx, bkt;
> > +	int ret = 0;
> > +
> > +	idx = srcu_read_lock(&kvm->srcu);
> > +
> > +	slots = kvm_memslots(kvm);
> > +	kvm_for_each_memslot(memslot, bkt, slots) {
> > +		if (!kvm_slot_has_gmem(memslot))
> > +			continue;
> > +
> > +		ret = realm_init_ipa_state(kvm, memslot->base_gfn,
> > +					   memslot->npages);
> > +		if (ret)
> > +			break;
> > +	}
> > +	srcu_read_unlock(&kvm->srcu, idx);
> > +
> > +	return ret;
> > +}
> > +
> >   int kvm_arm_rmi_populate(struct kvm *kvm,
> >   			 struct kvm_arm_rmi_populate *args)
> >   {
> > @@ -890,6 +922,10 @@ int kvm_activate_realm(struct kvm *kvm)
> >   			return ret;
> >   	}
> >   
> > +	ret = set_ripas_of_protected_regions(kvm);
> > +	if (ret)
> > +		return ret;
> > +
> >   	ret = rmi_realm_activate(virt_to_phys(realm->rd));
> >   	if (ret)
> >   		return -ENXIO;
>
> relam guest already does.
> 	for_each_mem_range(i, &start, &end) {
> 		if (rsi_set_memory_range_protected_safe(start, end)) {
> 			panic("Failed to set memory range to protected: %pa-%pa",
> 			      &start, &end);
> 		}
> 	}
>
> if so why is host required to do this ?

Ideally this should be a call from the VMM (i.e., user). Irrespective of
what the guest does (which the host has no knowledge about), the VMM/
user is better aware of what to do for a given guest. We have done this
implicitly in the KVM as a start, to keep the initial implementation
simple. This could be moved out to the VMM as UABI, if there is
sufficient demand for it.

TL,DR: This should be a host/deployer decision, not the Guest. There
may other guest OS, which do not do RIPAS_RAM early enough.

Suzuki