1 files changed, 116 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86/nested_invalid_cr3_test.c b/tools/testing/selftests/kvm/x86/nested_invalid_cr3_test.c
new file mode 100644
index 000000000000..a6b6da9cf7fe
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/nested_invalid_cr3_test.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2025, Google LLC.
+ *
+ * This test verifies that L1 fails to enter L2 with an invalid CR3, and
+ * succeeds otherwise.
+ */
+#include "kvm_util.h"
+#include "vmx.h"
+#include "svm_util.h"
+#include "kselftest.h"
+
+
+#define L2_GUEST_STACK_SIZE 64
+
+static void l2_guest_code(void)
+{
+	vmcall();
+}
+
+static void l1_svm_code(struct svm_test_data *svm)
+{
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	uintptr_t save_cr3;
+
+	generic_svm_setup(svm, l2_guest_code,
+			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+	/* Try to run L2 with invalid CR3 and make sure it fails */
+	save_cr3 = svm->vmcb->save.cr3;
+	svm->vmcb->save.cr3 = -1ull;
+	run_guest(svm->vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_ERR);
+
+	/* Now restore CR3 and make sure L2 runs successfully */
+	svm->vmcb->save.cr3 = save_cr3;
+	run_guest(svm->vmcb, svm->vmcb_gpa);
+	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);
+
+	GUEST_DONE();
+}
+
+static void l1_vmx_code(struct vmx_pages *vmx_pages)
+{
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	uintptr_t save_cr3;
+
+	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
+	GUEST_ASSERT(load_vmcs(vmx_pages));
+
+	prepare_vmcs(vmx_pages, l2_guest_code,
+		     &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+	/* Try to run L2 with invalid CR3 and make sure it fails */
+	save_cr3 = vmreadz(GUEST_CR3);
+	vmwrite(GUEST_CR3, -1ull);
+	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
+		     (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
+
+	/* Now restore CR3 and make sure L2 runs successfully */
+	vmwrite(GUEST_CR3, save_cr3);
+	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
+
+	GUEST_DONE();
+}
+
+static void l1_guest_code(void *data)
+{
+	if (this_cpu_has(X86_FEATURE_VMX))
+		l1_vmx_code(data);
+	else
+		l1_svm_code(data);
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	vm_vaddr_t guest_gva = 0;
+
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
+		     kvm_cpu_has(X86_FEATURE_SVM));
+
+	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
+
+	if (kvm_cpu_has(X86_FEATURE_VMX))
+		vcpu_alloc_vmx(vm, &guest_gva);
+	else
+		vcpu_alloc_svm(vm, &guest_gva);
+
+	vcpu_args_set(vcpu, 1, guest_gva);
+
+	for (;;) {
+		struct ucall uc;
+
+		vcpu_run(vcpu);
+		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT(uc);
+		case UCALL_SYNC:
+			break;
+		case UCALL_DONE:
+			goto done;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+	}
+
+done:
+	kvm_vm_free(vm);
+	return 0;
+}