Re: RFC KVM: arm64: selftest: stage 2 mapping helpers

[Oliver Upton <oliver.upton@linux.dev>]

On Wed, Oct 22, 2025 at 02:25:42PM +0900, Itaru Kitayama wrote:
> Hi Oliver,
> Thanks for your review. Below is the updated helper patch and a test program
> which does ERET in L1 guest (in guest_code). However, upon execution I keep 
> getting IABTs from lower EL.

I don't have the time to help debugging this, you'll need to spend some
time on this if you can.

> int main(void)
> {
> 	struct kvm_vm *vm;
> 	struct kvm_vcpu *vcpu;
> 	struct kvm_vcpu_init init = {};
> 
> 	/* Check we're on a NV2 hardware */
> 	if (!kvm_check_cap(KVM_CAP_ARM_EL2))
> 		exit(KSFT_SKIP);
> 
> 	vm = vm_create(1);
> 
> 	kvm_get_default_vcpu_target(vm, &init);
>         init.features[0] |= BIT(KVM_ARM_VCPU_HAS_EL2);
>         vcpu = aarch64_vcpu_add(vm, 0, &init, guest_code);

Keep in mind that aarch64_vcpu_add() will wind up initializing the EL2
CPU context when HAS_EL2 is set. To get a functional EL1 you'll need to
initialize the EL1 CPU context, including the MMU and allocating a
separate stack.

You can probably get away with reusing the EL2&0 page tables at EL1 so
long as the stage-2 translation is an identity mapping.

Thanks,
Oliver