1 files changed, 145 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c b/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c
new file mode 100644
index 000000000000..fad3634fd9eb
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+#include <signal.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+
+#include "kselftest.h"
+
+static void guest_ud_handler(struct ex_regs *regs)
+{
+	/* Loop on the ud2 until guest state is made invalid. */
+}
+
+static void guest_code(void)
+{
+	asm volatile("ud2");
+}
+
+static void __run_vcpu_with_invalid_state(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+
+	vcpu_run(vcpu);
+
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_INTERNAL_ERROR);
+	TEST_ASSERT(run->emulation_failure.suberror == KVM_INTERNAL_ERROR_EMULATION,
+		    "Expected emulation failure, got %d",
+		    run->emulation_failure.suberror);
+}
+
+static void run_vcpu_with_invalid_state(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * Always run twice to verify KVM handles the case where _KVM_ queues
+	 * an exception with invalid state and then exits to userspace, i.e.
+	 * that KVM doesn't explode if userspace ignores the initial error.
+	 */
+	__run_vcpu_with_invalid_state(vcpu);
+	__run_vcpu_with_invalid_state(vcpu);
+}
+
+static void set_timer(void)
+{
+	struct itimerval timer;
+
+	timer.it_value.tv_sec  = 0;
+	timer.it_value.tv_usec = 200;
+	timer.it_interval = timer.it_value;
+	TEST_ASSERT_EQ(setitimer(ITIMER_REAL, &timer, NULL), 0);
+}
+
+static void set_or_clear_invalid_guest_state(struct kvm_vcpu *vcpu, bool set)
+{
+	static struct kvm_sregs sregs;
+
+	if (!sregs.cr0)
+		vcpu_sregs_get(vcpu, &sregs);
+	sregs.tr.unusable = !!set;
+	vcpu_sregs_set(vcpu, &sregs);
+}
+
+static void set_invalid_guest_state(struct kvm_vcpu *vcpu)
+{
+	set_or_clear_invalid_guest_state(vcpu, true);
+}
+
+static void clear_invalid_guest_state(struct kvm_vcpu *vcpu)
+{
+	set_or_clear_invalid_guest_state(vcpu, false);
+}
+
+static struct kvm_vcpu *get_set_sigalrm_vcpu(struct kvm_vcpu *__vcpu)
+{
+	static struct kvm_vcpu *vcpu = NULL;
+
+	if (__vcpu)
+		vcpu = __vcpu;
+	return vcpu;
+}
+
+static void sigalrm_handler(int sig)
+{
+	struct kvm_vcpu *vcpu = get_set_sigalrm_vcpu(NULL);
+	struct kvm_vcpu_events events;
+
+	TEST_ASSERT(sig == SIGALRM, "Unexpected signal = %d", sig);
+
+	vcpu_events_get(vcpu, &events);
+
+	/*
+	 * If an exception is pending, attempt KVM_RUN with invalid guest,
+	 * otherwise rearm the timer and keep doing so until the timer fires
+	 * between KVM queueing an exception and re-entering the guest.
+	 */
+	if (events.exception.pending) {
+		set_invalid_guest_state(vcpu);
+		run_vcpu_with_invalid_state(vcpu);
+	} else {
+		set_timer();
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	TEST_REQUIRE(host_cpu_is_intel);
+	TEST_REQUIRE(!vm_is_unrestricted_guest(NULL));
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+	get_set_sigalrm_vcpu(vcpu);
+
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+
+	vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler);
+
+	/*
+	 * Stuff invalid guest state for L2 by making TR unusuable.  The next
+	 * KVM_RUN should induce a TRIPLE_FAULT in L2 as KVM doesn't support
+	 * emulating invalid guest state for L2.
+	 */
+	set_invalid_guest_state(vcpu);
+	run_vcpu_with_invalid_state(vcpu);
+
+	/*
+	 * Verify KVM also handles the case where userspace gains control while
+	 * an exception is pending and stuffs invalid state.  Run with valid
+	 * guest state and a timer firing every 200us, and attempt to enter the
+	 * guest with invalid state when the handler interrupts KVM with an
+	 * exception pending.
+	 */
+	clear_invalid_guest_state(vcpu);
+	TEST_ASSERT(signal(SIGALRM, sigalrm_handler) != SIG_ERR,
+		    "Failed to register SIGALRM handler, errno = %d (%s)",
+		    errno, strerror(errno));
+
+	set_timer();
+	run_vcpu_with_invalid_state(vcpu);
+}