Re: [PATCH v3 09/10] KVM: selftests: Support running stress save+restore and #PF test in L2

[Sean Christopherson]

On Mon, Jun 29, 2026, Yosry Ahmed wrote:
> +static bool parse_args_nested(int argc, char *argv[])
> +{
> +	bool nested = false;
> +	int opt;
> +
> +	while ((opt = getopt(argc, argv, "n")) != -1) {

Since the test ends up taking args anyways, might as well have it take the number
of iterations too.

But, why make it an either-or?  If nested is supported, run the test non-nested
and then run it nested.  While I am sloooooowly working towards utilizing Vipin's
selftest runner, IMO this is still basic functionality that should be tested by
default, i.e. shouldn't require fancy opt-in.

> +		switch (opt) {
> +		case 'n':
> +			nested = true;
> +			break;
> +		default:
> +			printf("Usage: %s [-n]\n", argv[0]);
> +			exit(1);
> +		}
> +	}
> +
> +	return nested;
> +}
> +
>  int main(int argc, char *argv[])
>  {
>  	struct kvm_x86_state *state;
> @@ -136,12 +188,24 @@ int main(int argc, char *argv[])
>  	struct kvm_vm *vm;
>  	struct ucall uc;
>  	u64 *pgtable;
> +	bool nested;
>  	gva_t gva;
>  	u64 pte;
>  
> -	vm = vm_create_with_one_vcpu(&vcpu, guest_access_memory);
> +	nested = parse_args_nested(argc, argv);
> +
> +	vm = vm_create_with_one_vcpu(&vcpu, nested ? l1_guest_code : guest_access_memory);
>  	vm_install_exception_handler(vm, PF_VECTOR, guest_pf_handler);
>  
> +	if (nested) {
> +		TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM) || kvm_cpu_has(X86_FEATURE_VMX));
> +		if (kvm_cpu_has(X86_FEATURE_SVM))
> +			vcpu_alloc_svm(vm, &gva);
> +		else
> +			vcpu_alloc_vmx(vm, &gva);
> +		vcpu_args_set(vcpu, 1, gva);
> +	}
> +
>  	pte_present_mask = PTE_PRESENT_MASK(&vm->mmu);
>  	pte_huge_mask = PTE_HUGE_MASK(&vm->mmu);
>  	sync_global_to_guest(vm, pte_present_mask);
> @@ -216,7 +280,7 @@ int main(int argc, char *argv[])
>  
>  	sync_global_from_guest(vm, guest_faults);
>  	TEST_ASSERT(guest_faults > 0, "No guest page faults triggered");
> -	pr_info("Guest page faults: %lu\n", guest_faults);
> +	pr_info("Guest page faults%s: %lu\n", nested ? " (in L2)" : "", guest_faults);
>  
>  	pthread_cancel(sigusr_thread);
>  	pthread_join(sigusr_thread, NULL);
> -- 
> 2.55.0.rc0.799.gd6f94ed593-goog
>