1 // SPDX-License-Identifier: GPL-2.0-only 2 #include "test_util.h" 3 #include "kvm_util.h" 4 #include "processor.h" 5 6 #include <signal.h> 7 #include <string.h> 8 #include <sys/ioctl.h> 9 #include <sys/time.h> 10 11 #include "kselftest.h" 12 13 static void guest_ud_handler(struct ex_regs *regs) 14 { 15 /* Loop on the ud2 until guest state is made invalid. */ 16 } 17 18 static void guest_code(void) 19 { 20 asm volatile("ud2"); 21 } 22 23 static void __run_vcpu_with_invalid_state(struct kvm_vcpu *vcpu) 24 { 25 struct kvm_run *run = vcpu->run; 26 27 vcpu_run(vcpu); 28 29 TEST_ASSERT(run->exit_reason == KVM_EXIT_INTERNAL_ERROR, 30 "Expected KVM_EXIT_INTERNAL_ERROR, got %d (%s)\n", 31 run->exit_reason, exit_reason_str(run->exit_reason)); 32 TEST_ASSERT(run->emulation_failure.suberror == KVM_INTERNAL_ERROR_EMULATION, 33 "Expected emulation failure, got %d\n", 34 run->emulation_failure.suberror); 35 } 36 37 static void run_vcpu_with_invalid_state(struct kvm_vcpu *vcpu) 38 { 39 /* 40 * Always run twice to verify KVM handles the case where _KVM_ queues 41 * an exception with invalid state and then exits to userspace, i.e. 42 * that KVM doesn't explode if userspace ignores the initial error. 43 */ 44 __run_vcpu_with_invalid_state(vcpu); 45 __run_vcpu_with_invalid_state(vcpu); 46 } 47 48 static void set_timer(void) 49 { 50 struct itimerval timer; 51 52 timer.it_value.tv_sec = 0; 53 timer.it_value.tv_usec = 200; 54 timer.it_interval = timer.it_value; 55 ASSERT_EQ(setitimer(ITIMER_REAL, &timer, NULL), 0); 56 } 57 58 static void set_or_clear_invalid_guest_state(struct kvm_vcpu *vcpu, bool set) 59 { 60 static struct kvm_sregs sregs; 61 62 if (!sregs.cr0) 63 vcpu_sregs_get(vcpu, &sregs); 64 sregs.tr.unusable = !!set; 65 vcpu_sregs_set(vcpu, &sregs); 66 } 67 68 static void set_invalid_guest_state(struct kvm_vcpu *vcpu) 69 { 70 set_or_clear_invalid_guest_state(vcpu, true); 71 } 72 73 static void clear_invalid_guest_state(struct kvm_vcpu *vcpu) 74 { 75 set_or_clear_invalid_guest_state(vcpu, false); 76 } 77 78 static struct kvm_vcpu *get_set_sigalrm_vcpu(struct kvm_vcpu *__vcpu) 79 { 80 static struct kvm_vcpu *vcpu = NULL; 81 82 if (__vcpu) 83 vcpu = __vcpu; 84 return vcpu; 85 } 86 87 static void sigalrm_handler(int sig) 88 { 89 struct kvm_vcpu *vcpu = get_set_sigalrm_vcpu(NULL); 90 struct kvm_vcpu_events events; 91 92 TEST_ASSERT(sig == SIGALRM, "Unexpected signal = %d", sig); 93 94 vcpu_events_get(vcpu, &events); 95 96 /* 97 * If an exception is pending, attempt KVM_RUN with invalid guest, 98 * otherwise rearm the timer and keep doing so until the timer fires 99 * between KVM queueing an exception and re-entering the guest. 100 */ 101 if (events.exception.pending) { 102 set_invalid_guest_state(vcpu); 103 run_vcpu_with_invalid_state(vcpu); 104 } else { 105 set_timer(); 106 } 107 } 108 109 int main(int argc, char *argv[]) 110 { 111 struct kvm_vcpu *vcpu; 112 struct kvm_vm *vm; 113 114 TEST_REQUIRE(is_intel_cpu()); 115 TEST_REQUIRE(!vm_is_unrestricted_guest(NULL)); 116 117 vm = vm_create_with_one_vcpu(&vcpu, guest_code); 118 get_set_sigalrm_vcpu(vcpu); 119 120 vm_init_descriptor_tables(vm); 121 vcpu_init_descriptor_tables(vcpu); 122 123 vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler); 124 125 /* 126 * Stuff invalid guest state for L2 by making TR unusuable. The next 127 * KVM_RUN should induce a TRIPLE_FAULT in L2 as KVM doesn't support 128 * emulating invalid guest state for L2. 129 */ 130 set_invalid_guest_state(vcpu); 131 run_vcpu_with_invalid_state(vcpu); 132 133 /* 134 * Verify KVM also handles the case where userspace gains control while 135 * an exception is pending and stuffs invalid state. Run with valid 136 * guest state and a timer firing every 200us, and attempt to enter the 137 * guest with invalid state when the handler interrupts KVM with an 138 * exception pending. 139 */ 140 clear_invalid_guest_state(vcpu); 141 TEST_ASSERT(signal(SIGALRM, sigalrm_handler) != SIG_ERR, 142 "Failed to register SIGALRM handler, errno = %d (%s)", 143 errno, strerror(errno)); 144 145 set_timer(); 146 run_vcpu_with_invalid_state(vcpu); 147 } 148