Re: [PATCH net-next v3] selftests/vsock: add initial vmtest.sh for vsock

[Paolo Abeni <pabeni@redhat.com>]

On 4/29/25 1:48 AM, Bobby Eshleman wrote:
> This commit introduces a new vmtest.sh runner for vsock.
> 
> It uses virtme-ng/qemu to run tests in a VM. The tests validate G2H,
> H2G, and loopback. The testing tools from tools/testing/vsock/ are
> reused. Currently, only vsock_test is used.
> 
> VMCI and hyperv support is automatically built, though not used.
> 
> Only tested on x86.
> 
> To run:
> 
>   $ tools/testing/selftests/vsock/vmtest.sh
> 
> or
> 
>   $ make -C tools/testing/selftests TARGETS=vsock run_tests
> 
> Results:
> 	# linux/tools/testing/selftests/vsock/vmtest.log
> 	setup:  Building kernel and tests
> 	setup:  Booting up VM
> 	setup:  VM booted up
> 	test:vm_server_host_client:guest:       Control socket listening on 0.0.0.0:51000
> 	test:vm_server_host_client:guest:       Control socket connection accepted...
> 	[...]
> 	test:vm_loopback:guest: 30 - SOCK_STREAM retry failed connect()...ok
> 	test:vm_loopback:guest: 31 - SOCK_STREAM SO_LINGER null-ptr-deref...ok
> 	test:vm_loopback:guest: 31 - SOCK_STREAM SO_LINGER null-ptr-deref...ok
> 
> Future work can include vsock_diag_test.
> 
> vmtest.sh is loosely based off of tools/testing/selftests/net/pmtu.sh,
> which was picked out of the bag of tests I knew to work with NIPA.
> 
> Because vsock requires a VM to test anything other than loopback, this
> patch adds vmtest.sh as a kselftest itself. This is different than other
> systems that have a "vmtest.sh", where it is used as a utility script to
> spin up a VM to run the selftests as a guest (but isn't hooked into
> kselftest). This aspect is worth review, as I'm not aware of all of the
> enviroments where this would run.

I think this approach is interesting, but I think it will need some
additional more work, see below...

[...]

> diff --git a/tools/testing/selftests/vsock/settings b/tools/testing/selftests/vsock/settings
> new file mode 100644
> index 0000000000000000000000000000000000000000..e7b9417537fbc4626153b72e8f295ab4594c844b
> --- /dev/null
> +++ b/tools/testing/selftests/vsock/settings
> @@ -0,0 +1 @@
> +timeout=0

We need a reasonable, bounded runtime for nipa integration.

> diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
> new file mode 100755
> index 0000000000000000000000000000000000000000..d70b9446e531d6d20beb24ddeda2cf0a9f7e9a39
> --- /dev/null
> +++ b/tools/testing/selftests/vsock/vmtest.sh
> @@ -0,0 +1,354 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (c) 2025 Meta Platforms, Inc. and affiliates
> +#
> +# Dependencies:
> +#		* virtme-ng
> +#		* busybox-static (used by virtme-ng)
> +#		* qemu	(used by virtme-ng)

You should probably check for such tools presence and bail out with skip
otherwise.

> +
> +SCRIPT_DIR="$(cd -P -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
> +KERNEL_CHECKOUT=$(realpath ${SCRIPT_DIR}/../../../..)

This is not going to work if/when the self-tests are installed in their
own directory via `make install` in the tools/testing/selftests/
directory, and that use case is supposed to work.

At very least you should check for the expected layout and skip otherwise.

> +QEMU=$(command -v qemu-system-$(uname -m))
> +VERBOSE=0
> +SKIP_BUILD=0
> +VSOCK_TEST=${KERNEL_CHECKOUT}/tools/testing/vsock/vsock_test
> +
> +TEST_GUEST_PORT=51000
> +TEST_HOST_PORT=50000
> +TEST_HOST_PORT_LISTENER=50001
> +SSH_GUEST_PORT=22
> +SSH_HOST_PORT=2222
> +VSOCK_CID=1234
> +WAIT_PERIOD=3
> +WAIT_PERIOD_MAX=20
> +
> +QEMU_PIDFILE=/tmp/qemu.pid
> +
> +# virtme-ng offers a netdev for ssh when using "--ssh", but we also need a
> +# control port forwarded for vsock_test.  Because virtme-ng doesn't support
> +# adding an additional port to forward to the device created from "--ssh" and
> +# virtme-init mistakenly sets identical IPs to the ssh device and additional
> +# devices, we instead opt out of using --ssh, add the device manually, and also
> +# add the kernel cmdline options that virtme-init uses to setup the interface.
> +QEMU_OPTS=""
> +QEMU_OPTS="${QEMU_OPTS} -netdev user,id=n0,hostfwd=tcp::${TEST_HOST_PORT}-:${TEST_GUEST_PORT}"
> +QEMU_OPTS="${QEMU_OPTS},hostfwd=tcp::${SSH_HOST_PORT}-:${SSH_GUEST_PORT}"
> +QEMU_OPTS="${QEMU_OPTS} -device virtio-net-pci,netdev=n0"
> +QEMU_OPTS="${QEMU_OPTS} -device vhost-vsock-pci,guest-cid=${VSOCK_CID}"
> +QEMU_OPTS="${QEMU_OPTS} --pidfile ${QEMU_PIDFILE}"
> +KERNEL_CMDLINE="virtme.dhcp net.ifnames=0 biosdevname=0 virtme.ssh virtme_ssh_user=$USER"
> +
> +LOG=${SCRIPT_DIR}/vmtest.log
> +
> +#		Name				Description
> +avail_tests="
> +	vm_server_host_client	Run vsock_test in server mode on the VM and in client mode on the host.	
> +	vm_client_host_server	Run vsock_test in client mode on the VM and in server mode on the host.	
> +	vm_loopback		Run vsock_test using the loopback transport in the VM.	
> +"
> +
> +usage() {
> +	echo
> +	echo "$0 [OPTIONS] [TEST]..."
> +	echo "If no TEST argument is given, all tests will be run."
> +	echo
> +	echo "Options"
> +	echo "  -v: verbose output"
> +	echo "  -s: skip build"
> +	echo
> +	echo "Available tests${avail_tests}"
> +	exit 1
> +}
> +
> +die() {
> +	echo "$*" >&2
> +	exit 1
> +}
> +
> +vm_ssh() {
> +	ssh -q -o UserKnownHostsFile=/dev/null -p 2222 localhost $*
> +	return $?
> +}
> +
> +cleanup() {
> +	if [[ -f "${QEMU_PIDFILE}" ]]; then
> +		pkill -SIGTERM -F ${QEMU_PIDFILE} 2>&1 >/dev/null
> +	fi
> +}
> +
> +build() {
> +	log_setup "Building kernel and tests"
> +
> +	pushd ${KERNEL_CHECKOUT} >/dev/null
> +	vng \
> +		--kconfig \
> +		--config ${KERNEL_CHECKOUT}/tools/testing/selftests/vsock/config.vsock
> +	make -j$(nproc)
> +	make -C ${KERNEL_CHECKOUT}/tools/testing/vsock
> +	popd >/dev/null

I think it would be better to avoid the kernel rebuild. A possible
alternative could be including in 'config' the needed knobs for vng's
sake and re-use the running kernel.

Cheers,

Paolo