qemu: Add new test tracing_exception_injection

This patch adds a new test that verifies whether the
host allows tracing of exception injection in KVM.
Signed-off-by: NYunping Zheng <yunzheng@redhat.com>

qemu/tests/cfg/tracing_exception_injection.cfg

+- tracing_exception_injection:
+    type = tracing_exception_injection

qemu/tests/tracing_exception_injection.py

+import logging
+from autotest.client import utils, os_dep
+from autotest.client.shared import error
+
+
+@error.context_aware
+def run_tracing_exception_injection(test, params, env):
+    """
+    Run tracing of exception injection test
+
+    1) Boot the main vm, or just verify it if it's already booted.
+    2) In host run kvm_stat, it should work.
+    3) In host check host allow tracing of exception injection in KVM.
+
+    @param test: QEMU test object.
+    @param params: Dictionary with the test parameters.
+    @param env: Dictionary with test environment.
+    """
+    error.context("Get the main VM", logging.info)
+    vm = env.get_vm(params["main_vm"])
+    vm.verify_alive()
+
+    error.context("Check that kvm_stat works in host", logging.info)
+    kvm_stat_bin = os_dep.command("kvm_stat")
+    check_cmd = "%s -1 -f exits" % kvm_stat_bin
+    host_cmd_output = utils.system_output(check_cmd)
+    if host_cmd_output:
+        if host_cmd_output.split()[1] == '0':
+            raise error.TestFail("kvm_stat did not provide the expected "
+                                 "output: %s" % host_cmd_output)
+        logging.info("kvm_stat provided the expected output")
+    logging.info("Host cmd output '%s'", host_cmd_output)
+
+    error.context("Check that host allows tracing of exception injection in KVM",
+                  logging.info)
+    exec_cmd = "grep kvm:kvm_inj_exception "
+    exec_cmd += " /sys/kernel/debug/tracing/available_events"
+    inj_check_cmd = params.get("injection_check_cmd", exec_cmd)
+    try:
+        utils.run(inj_check_cmd)
+    except error.CmdError:
+        err_msg = "kvm:kvm_inj_exception is not an avaliable event in host"
+        raise error.TestFail(err_msg)
+    logging.info("Host supports tracing of exception injection in KVM")