ide: Fix segfault when flushing a device that doesn't exist

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/tests/ide-test.c b/tests/ide-test.c
index a77a037..ffce6ed 100644
--- a/tests/ide-test.c
+++ b/tests/ide-test.c
@@ -564,6 +564,19 @@
     ide_test_quit();
 }
 
+static void test_flush_nodev(void)
+{
+    ide_test_start("");
+
+    /* FLUSH CACHE command on device 0*/
+    outb(IDE_BASE + reg_device, 0);
+    outb(IDE_BASE + reg_command, CMD_FLUSH_CACHE);
+
+    /* Just testing that qemu doesn't crash... */
+
+    ide_test_quit();
+}
+
 int main(int argc, char **argv)
 {
     const char *arch = qtest_get_arch();
@@ -601,6 +614,7 @@
     qtest_add_func("/ide/bmdma/teardown", test_bmdma_teardown);
 
     qtest_add_func("/ide/flush", test_flush);
+    qtest_add_func("/ide/flush_nodev", test_flush_nodev);
 
     qtest_add_func("/ide/retry/flush", test_retry_flush);