[PATCH v3 01/14] KVM: Allow architectures to disallow pre-fault

[Lorenzo Stoakes (ARM)]

On Wed, Sep 23, 2026 at 11:54:15AM +0100, Fuad Tabba wrote:
> Hi Lorenzo,
>
> On Tue, 22 Sep 2026 19:07:53 +0100, Oliver Upton <oupton at kernel.org> wrote:
> [...]
> > I'd favor doing something like below and sticking the comment inline in
> > the ioctl handler. Unless I'm missing something blatantly obvious, I
> > don't see why the x86 or s390 pre-conditions can't be tested early too.
> [...]
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> [...]
> > +int kvm_arch_pre_fault_allowed(struct kvm_vcpu *vcpu)
> > +{
> > +        if (!kvm_vcpu_initialized(vcpu))
> > +                return -ENOEXEC;
> > +
> > +        return 0;
> > +}
>
> The same goes for arm64's pKVM check: kvm_arch_vcpu_pre_fault_memory()
> returns -EOPNOTSUPP for is_protected_kvm_enabled() only after
> vcpu_load(), so on a pKVM host the ioctl loads a vCPU the hypervisor
> may not have created yet before rejecting it. Could that check move
> into kvm_arch_pre_fault_allowed() as well?

Ack yeah that sounds good, will do for v4!

>
> Cheers,
> /fuad

--
Cheers, Lorenzo