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