KVM: Allow expected KVM_RUN errors in tst_kvm_run_instance()

Add a new parameter to tst_kvm_run_instance() for expected errno value,
e.g. EINTR for testing the possiblity to kill running guest. When
ioctl(KVM_RUN) fails with the expected errno, tst_kvm_run_instance()
will return -1 without terminating the test.

Default tst_kvm_run() function expects no KVM_RUN errors.

Signed-off-by: Martin Doucha <mdoucha@suse.cz>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

Author: mdoucha

doc/kvm-test-api.txt

@@ -194,9 +194,12 @@ previously allocated guarded buffers.
   with at least `ram_size` bytes of memory. The VM instance info will be
   stored in `inst`.
 
-- `void tst_kvm_run_instance(struct tst_kvm_instance *inst)` – Executes
-  the program installed in KVM virtual machine `inst`. Any result messages
-  returned by the VM will be automatically printed to controller program output.
+- `int tst_kvm_run_instance(struct tst_kvm_instance *inst, int exp_errno)` –
+  Executes the program installed in KVM virtual machine `inst`. Any result
+  messages returned by the VM will be automatically printed to controller
+  program output. Returns zero. If `exp_errno` is non-zero, the VM execution
+  syscall is allowed to fail with the `exp_errno` error code and
+  `tst_kvm_run_instance()` will return -1 instead of terminating the test.
 
 - `void tst_kvm_destroy_instance(struct tst_kvm_instance *inst)` – Deletes
   the KVM virtual machine `inst`. Note that the guarded buffers assigned

testcases/kernel/kvm/include/kvm_host.h

@@ -125,9 +125,11 @@ struct kvm_cpuid2 *tst_kvm_get_cpuid(int sysfd);
 void tst_kvm_create_instance(struct tst_kvm_instance *inst, size_t ram_size);
 
 /*
- * Execute the given KVM instance and print results.
+ * Execute the given KVM instance and print results. If ioctl(KVM_RUN) is
+ * expected to fail, pass the expected error code in exp_errno, otherwise
+ * set it to zero. Returns last value returned by ioctl(KVM_RUN).
  */
-void tst_kvm_run_instance(struct tst_kvm_instance *inst);
+int tst_kvm_run_instance(struct tst_kvm_instance *inst, int exp_errno);
 
 /*
  * Close the given KVM instance.

testcases/kernel/kvm/lib_host.c

@@ -234,14 +234,28 @@ void tst_kvm_create_instance(struct tst_kvm_instance *inst, size_t ram_size)
 	inst->result->message[0] = '\0';
 }
 
-void tst_kvm_run_instance(struct tst_kvm_instance *inst)
+int tst_kvm_run_instance(struct tst_kvm_instance *inst, int exp_errno)
 {
 	struct kvm_regs regs;
+	int ret;
 
 	while (1) {
 		inst->result->result = KVM_TNONE;
 		inst->result->message[0] = '\0';
-		SAFE_IOCTL(inst->vcpu_fd, KVM_RUN, 0);
+		errno = 0;
+		ret = ioctl(inst->vcpu_fd, KVM_RUN, 0);
+
+		if (ret == -1) {
+			if (errno == exp_errno)
+				return ret;
+
+			tst_brk(TBROK | TERRNO, "ioctl(KVM_RUN) failed");
+		}
+
+		if (ret < 0) {
+			tst_brk(TBROK | TERRNO,
+				"Invalid ioctl(KVM_RUN) return value %d", ret);
+		}
 
 		if (inst->vcpu_info->exit_reason != KVM_EXIT_HLT) {
 			SAFE_IOCTL(inst->vcpu_fd, KVM_GET_REGS, &regs);
@@ -255,6 +269,8 @@ void tst_kvm_run_instance(struct tst_kvm_instance *inst)
 
 		tst_kvm_print_result(inst);
 	}
+
+	return ret;
 }
 
 void tst_kvm_destroy_instance(struct tst_kvm_instance *inst)
@@ -280,7 +296,7 @@ void tst_kvm_setup(void)
 void tst_kvm_run(void)
 {
 	tst_kvm_create_instance(&test_vm, DEFAULT_RAM_SIZE);
-	tst_kvm_run_instance(&test_vm);
+	tst_kvm_run_instance(&test_vm, 0);
 	tst_kvm_destroy_instance(&test_vm);
 	tst_free_all();
 }