[kvm-unit-tests PATCH v5 1/4] runtime: add support for panic tests

[Nico Boehr <nrb@linux.ibm.com>]

QEMU supports a guest state "guest-panicked" which indicates something
in the guest went wrong, for example on s390x, when an external
interrupt loop was triggered.

Since the guest does not continue to run when it is in the
guest-panicked state, it is currently impossible to write panicking
tests in kvm-unit-tests. Support from the runtime is needed to check
that the guest enters the guest-panicked state.

Similar to migration tests, add a new group panic. Tests in this
group must enter the guest-panicked state to succeed.

The runtime will spawn a QEMU instance, connect to the QMP and listen
for events. To parse the QMP protocol, jq[1] is used. Same as with
netcat in the migration tests, panic tests won't run if jq is not
installed.

The guest is created in the stopped state and only continued when
connection to the QMP was successful. This ensures no events are missed
between QEMU start and the connect to the QMP.

[1] https://stedolan.github.io/jq/

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 s390x/run             |  2 +-
 scripts/arch-run.bash | 49 +++++++++++++++++++++++++++++++++++++++++++
 scripts/runtime.bash  |  3 +++
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/s390x/run b/s390x/run
index 24138f6803be..f1111dbdbe62 100755
--- a/s390x/run
+++ b/s390x/run
@@ -30,7 +30,7 @@ M+=",accel=$ACCEL"
 command="$qemu -nodefaults -nographic $M"
 command+=" -chardev stdio,id=con0 -device sclpconsole,chardev=con0"
 command+=" -kernel"
-command="$(migration_cmd) $(timeout_cmd) $command"
+command="$(panic_cmd) $(migration_cmd) $(timeout_cmd) $command"
 
 # We return the exit code via stdout, not via the QEMU return code
 run_qemu_status $command "$@"
diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
index 0dfaf017db0a..51e4b97b27d1 100644
--- a/scripts/arch-run.bash
+++ b/scripts/arch-run.bash
@@ -104,6 +104,14 @@ qmp ()
 	echo '{ "execute": "qmp_capabilities" }{ "execute":' "$2" '}' | ncat -U $1
 }
 
+qmp_events ()
+{
+	while ! test -S "$1"; do sleep 0.1; done
+	echo '{ "execute": "qmp_capabilities" }{ "execute": "cont" }' |
+		ncat --no-shutdown -U $1 |
+		jq -c 'select(has("event"))'
+}
+
 run_migration ()
 {
 	if ! command -v ncat >/dev/null 2>&1; then
@@ -164,6 +172,40 @@ run_migration ()
 	return $ret
 }
 
+run_panic ()
+{
+	if ! command -v ncat >/dev/null 2>&1; then
+		echo "${FUNCNAME[0]} needs ncat (netcat)" >&2
+		return 77
+	fi
+
+	if ! command -v jq >/dev/null 2>&1; then
+		echo "${FUNCNAME[0]} needs jq" >&2
+		return 77
+	fi
+
+	qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
+
+	trap 'kill 0; exit 2' INT TERM
+	trap 'rm -f ${qmp}' RETURN EXIT
+
+	# start VM stopped so we don't miss any events
+	eval "$@" -chardev socket,id=mon1,path=${qmp},server=on,wait=off \
+		-mon chardev=mon1,mode=control -S &
+
+	panic_event_count=$(qmp_events ${qmp} | jq -c 'select(.event == "GUEST_PANICKED")' | wc -l)
+	if [ "$panic_event_count" -lt 1 ]; then
+		echo "FAIL: guest did not panic"
+		ret=3
+	else
+		# some QEMU versions report multiple panic events
+		echo "PASS: guest panicked"
+		ret=1
+	fi
+
+	return $ret
+}
+
 migration_cmd ()
 {
 	if [ "$MIGRATION" = "yes" ]; then
@@ -171,6 +213,13 @@ migration_cmd ()
 	fi
 }
 
+panic_cmd ()
+{
+	if [ "$PANIC" = "yes" ]; then
+		echo "run_panic"
+	fi
+}
+
 search_qemu_binary ()
 {
 	local save_path=$PATH
diff --git a/scripts/runtime.bash b/scripts/runtime.bash
index bbf87cf4ed3f..f8794e9a25ce 100644
--- a/scripts/runtime.bash
+++ b/scripts/runtime.bash
@@ -145,6 +145,9 @@ function run()
     if find_word "migration" "$groups"; then
         cmdline="MIGRATION=yes $cmdline"
     fi
+    if find_word "panic" "$groups"; then
+        cmdline="PANIC=yes $cmdline"
+    fi
     if [ "$verbose" = "yes" ]; then
         echo $cmdline
     fi
-- 
2.36.1