On Thu, Sep 10, 2026 at 07:57:03PM +0100, Fuad Tabba wrote:
> Hi,
>
> On Tue, 25 Aug 2026 at 17:02, Lorenzo Stoakes (ARM) <[email protected]> wrote:
> ..
> > +int main(void)
> > +{
> > + struct nested_s2_state s2;
> > + struct kvm_vcpu_init init;
> > + struct kvm_vcpu *vcpu;
> > + struct kvm_vm *vm;
> > + struct ucall uc;
> > + u64 npages;
> > +
> > + TEST_REQUIRE(kvm_check_cap(KVM_CAP_ARM_EL2));
>
> Would test_supports_el2() work better here? It honours the NV=0
> opt-out, and since HAS_EL2 is set unconditionally below, NV=0 doesn't
> disable this test as things stand.
That sounds sensible :) Will fix on respin.
>
> Cheers,
> /fuad
>
> > + TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
> > +
> > + 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);
> > + kvm_arch_vm_finalize_vcpus(vm);
> > +
> > + npages = TEST_MEM_SIZE / vm->page_size;
> > + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, TEST_MEM_GPA,
> > + TEST_MEM_SLOT, npages, 0);
> > + virt_map(vm, TEST_MEM_GPA, TEST_MEM_GPA, npages);
> > +
> > + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> > + NESTED_S2_ROOT_GPA, NESTED_S2_ROOT_SLOT,
> > + vm_adjust_num_guest_pages(vm->mode, 1),
> > 0);
> > +
> > + /* Run the guest until it has ERET'd from vEL2 to vEL1. */
> > + vcpu_run(vcpu);
> > + switch (get_ucall(vcpu, &uc)) {
> > + case UCALL_SYNC:
> > + TEST_ASSERT_EQ(uc.args[1], 1);
> > + break;
> > + case UCALL_ABORT:
> > + REPORT_GUEST_ASSERT(uc);
> > + break;
> > + default:
> > + TEST_FAIL("Unhandled ucall: %ld", uc.cmd);
> > + }
> > +
> > + /*
> > + * The vCPU's last-run context is vEL1, backed by a shadow stage-2
> > + * MMU. Enable nested stage-2 with an empty root so that the ioctl
> > + * fails if it tries to interpret the userspace GPA as an L2 IPA.
> > + *
> > + * Prefault in two halves so that the second ioctl exercises a
> > + * repeated shadow-MMU attach and canonical stage-2 swap.
> > + *
> > + * (Note that an implementation that wrongly populates shadow
> > + * stage-2 page tables would not be caught as userland can't
> > + * inspect these.)
> > + */
> > + s2 = enable_empty_nested_s2(vcpu);
> > + pre_fault(vcpu, TEST_MEM_GPA, TEST_MEM_SIZE / 2);
> > + pre_fault(vcpu, TEST_MEM_GPA + TEST_MEM_SIZE / 2, TEST_MEM_SIZE /
> > 2);
> > + restore_nested_s2(vcpu, &s2);
> > +
> > + /* Resume at vEL1 and touch the prefaulted range. */
> > + vcpu_run(vcpu);
> > + switch (get_ucall(vcpu, &uc)) {
> > + case UCALL_DONE:
> > + break;
> > + case UCALL_ABORT:
> > + REPORT_GUEST_ASSERT(uc);
> > + break;
> > + default:
> > + TEST_FAIL("Unhandled ucall: %ld", uc.cmd);
> > + }
> > +
> > + kvm_vm_free(vm);
> > + return 0;
> > +}
> >
> > --
> > 2.55.0
> >
--
Cheers, Lorenzo
