nested_invalid_cr3_test.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2025, Google LLC.
  4 *
  5 * This test verifies that L1 fails to enter L2 with an invalid CR3, and
  6 * succeeds otherwise.
  7 */
  8#include "kvm_util.h"
  9#include "vmx.h"
 10#include "svm_util.h"
 11#include "kselftest.h"
 12
 13
 14#define L2_GUEST_STACK_SIZE 64
 15
 16static void l2_guest_code(void)
 17{
 18	vmcall();
 19}
 20
 21static void l1_svm_code(struct svm_test_data *svm)
 22{
 23	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 24	uintptr_t save_cr3;
 25
 26	generic_svm_setup(svm, l2_guest_code,
 27			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 28
 29	/* Try to run L2 with invalid CR3 and make sure it fails */
 30	save_cr3 = svm->vmcb->save.cr3;
 31	svm->vmcb->save.cr3 = -1ull;
 32	run_guest(svm->vmcb, svm->vmcb_gpa);
 33	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_ERR);
 34
 35	/* Now restore CR3 and make sure L2 runs successfully */
 36	svm->vmcb->save.cr3 = save_cr3;
 37	run_guest(svm->vmcb, svm->vmcb_gpa);
 38	GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);
 39
 40	GUEST_DONE();
 41}
 42
 43static void l1_vmx_code(struct vmx_pages *vmx_pages)
 44{
 45	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 46	uintptr_t save_cr3;
 47
 48	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
 49	GUEST_ASSERT(load_vmcs(vmx_pages));
 50
 51	prepare_vmcs(vmx_pages, l2_guest_code,
 52		     &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 53
 54	/* Try to run L2 with invalid CR3 and make sure it fails */
 55	save_cr3 = vmreadz(GUEST_CR3);
 56	vmwrite(GUEST_CR3, -1ull);
 57	GUEST_ASSERT(!vmlaunch());
 58	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
 59		     (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
 60
 61	/* Now restore CR3 and make sure L2 runs successfully */
 62	vmwrite(GUEST_CR3, save_cr3);
 63	GUEST_ASSERT(!vmlaunch());
 64	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 65
 66	GUEST_DONE();
 67}
 68
 69static void l1_guest_code(void *data)
 70{
 71	if (this_cpu_has(X86_FEATURE_VMX))
 72		l1_vmx_code(data);
 73	else
 74		l1_svm_code(data);
 75}
 76
 77int main(int argc, char *argv[])
 78{
 79	struct kvm_vcpu *vcpu;
 80	struct kvm_vm *vm;
 81	vm_vaddr_t guest_gva = 0;
 82
 83	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
 84		     kvm_cpu_has(X86_FEATURE_SVM));
 85
 86	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
 87
 88	if (kvm_cpu_has(X86_FEATURE_VMX))
 89		vcpu_alloc_vmx(vm, &guest_gva);
 90	else
 91		vcpu_alloc_svm(vm, &guest_gva);
 92
 93	vcpu_args_set(vcpu, 1, guest_gva);
 94
 95	for (;;) {
 96		struct ucall uc;
 97
 98		vcpu_run(vcpu);
 99		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
100
101		switch (get_ucall(vcpu, &uc)) {
102		case UCALL_ABORT:
103			REPORT_GUEST_ASSERT(uc);
104		case UCALL_SYNC:
105			break;
106		case UCALL_DONE:
107			goto done;
108		default:
109			TEST_FAIL("Unknown ucall %lu", uc.cmd);
110		}
111	}
112
113done:
114	kvm_vm_free(vm);
115	return 0;
116}