kernel-test: don't try to use KVM if not available

Disable KVM if /dev/kvm is missing, as it is apparently the case on our
jenkins nodes. This makes the tests run a bit slower, but not much. Add
kernel_test_wait_for_vm to sleep until the VM is booted up (~5s instead
of ~1s without KVM), so the first test in the testsuite does not fail
when using KVM.

The variable is useful to test the non-KVM code path even if KVM is
available on the host.

Related: OS#3208
Change-Id: I1f337af1e2de6db05b22636bc31a535404235559

README.md

@@ -35,6 +35,7 @@ be used for other testsuites in the future.
 
 Environment variables:
 * `KERNEL_TEST`: set to 1 to run the SUT in QEMU
+* `KERNEL_TEST_KVM`: set to 0 to disable KVM acceleration
 * `KERNEL_BUILD`: set to 1 to build the kernel instead of using the
   pre-built one
 * `KERNEL_REMOTE_NAME`: git remote name (to add multiple git

jenkins-common.sh

@@ -194,6 +194,12 @@ set_clean_up_trap() {
 	trap clean_up_common EXIT INT TERM 0
 }
 
+docker_kvm_param() {
+	if [ "$KERNEL_TEST_KVM" != 0 ]; then
+		echo "--device /dev/kvm:/dev/kvm"
+	fi
+}
+
 # Generate the initrd, and optionally build a kernel, for tests that involve
 # kernel modules. Boot the kernel once in QEMU inside docker to verify that it
 # works. See README.md for description of the KERNEL_* environment variables.
@@ -212,6 +218,15 @@ kernel_test_prepare() {
 	local docker_image="$4"
 	shift 4
 
+	# Store KVM availibility in global KERNEL_TEST_KVM
+	if [ -z "$KERNEL_TEST_KVM" ]; then
+		if [ -e "/dev/kvm" ]; then
+			KERNEL_TEST_KVM=1
+		else
+			KERNEL_TEST_KVM=0
+		fi
+	fi
+
 	mkdir -p "$CACHE_DIR/kernel-test"
 
 	cp "$kernel_config_fragment" \
@@ -221,7 +236,7 @@ kernel_test_prepare() {
 
 	docker run \
 		--cap-add=NET_ADMIN \
-		--device /dev/kvm:/dev/kvm \
+		$(docker_kvm_param) \
 		--device /dev/net/tun:/dev/net/tun \
 		-v "$CACHE_DIR:/cache" \
 		-v "$KERNEL_TEST_DIR:/kernel-test:ro" \
@@ -235,6 +250,31 @@ kernel_test_prepare() {
 		"/kernel-test/prepare.sh"
 }
 
+# Wait until the linux kernel is booted inside QEMU inside docker, and the
+# initrd is right before running the project-specific commands (e.g. starting
+# osmo-ggsn). This may take a few seconds if running without KVM.
+# $1: path to the VM's log file
+kernel_test_wait_for_vm() {
+	local log="$1"
+	local i
+
+	if [ "$KERNEL_TEST" != 1 ]; then
+		return
+	fi
+
+	for i in $(seq 1 10); do
+		sleep 1
+
+		if grep -q KERNEL_TEST_VM_IS_READY "$log"; then
+			return
+		fi
+	done
+
+	# Let clean_up_common kill the VM
+	echo "Timeout while waiting for kernel test VM"
+	exit 1
+}
+
 set -x
 
 # non-jenkins execution: assume local user name

scripts/kernel-test/initrd-init.sh

@@ -22,6 +22,8 @@ fi
 ip link set lo up
 ip link set eth0 up
 
+echo "KERNEL_TEST_VM_IS_READY"
+
 if grep -q SMOKE_TEST /proc/cmdline; then
 	# Called from scripts/kernel-test/prepare.sh:kernel_smoke_test() to
 	# verify that the kernel + initramfs boot up properly. Output this

scripts/kernel-test/run-qemu.sh

@@ -13,8 +13,14 @@ KERNEL_CMDLINE="
 	$@
 "
 
+if [ -e /dev/kvm ]; then
+	MACHINE_ARG="-machine pc,accel=kvm"
+else
+	MACHINE_ARG="-machine pc"
+fi
+
 qemu-system-x86_64 \
-	-machine pc,accel=kvm \
+	$MACHINE_ARG \
 	-smp 1 \
 	-m 512M \
 	-nodefconfig -no-user-config -nodefaults -display none \

ttcn3-ggsn-test/jenkins.sh

@@ -41,7 +41,7 @@ if [ "$KERNEL_TEST" = "1" ]; then
 	GGSN_CMD="/kernel-test/run-qemu.sh"
 	GGSN_DOCKER_ARGS="
 		$(docker_network_params $SUBNET 200)
-		--device /dev/kvm:/dev/kvm
+		$(docker_kvm_param)
 		-v "$KERNEL_TEST_DIR:/kernel-test:ro"
 		-v "$CACHE_DIR:/cache"
 		"
@@ -64,6 +64,8 @@ docker run	--cap-add=NET_ADMIN \
 		$REPO_USER/osmo-ggsn-$IMAGE_SUFFIX \
 		/bin/sh -c "$GGSN_CMD >/data/osmo-ggsn.log 2>&1"
 
+kernel_test_wait_for_vm "$VOL_BASE_DIR/ggsn/osmo-ggsn.log"
+
 # start docker container with testsuite in foreground
 docker run	--rm \
 		--sysctl net.ipv6.conf.all.disable_ipv6=0 \