Re: [PATCH v1 17/17] perf test kvm: Add some basic perf kvm test coverage

[Namhyung Kim <namhyung@kernel.org>]

On Sat, Nov 22, 2025 at 12:19:29AM -0800, Ian Rogers wrote:
> Setup qemu with KVM then run kvm stat and some host
> recording/reporting/build-id tests.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/tests/shell/kvm.sh | 154 ++++++++++++++++++++++++++++++++++
>  1 file changed, 154 insertions(+)
>  create mode 100755 tools/perf/tests/shell/kvm.sh
> 
> diff --git a/tools/perf/tests/shell/kvm.sh b/tools/perf/tests/shell/kvm.sh
> new file mode 100755
> index 000000000000..2fafde1a29cc
> --- /dev/null
> +++ b/tools/perf/tests/shell/kvm.sh
> @@ -0,0 +1,154 @@
> +#!/bin/bash
> +# perf kvm tests
> +# SPDX-License-Identifier: GPL-2.0
> +
> +set -e
> +
> +err=0
> +perfdata=$(mktemp /tmp/__perf_kvm_test.perf.data.XXXXX)
> +qemu_pid_file=$(mktemp /tmp/__perf_kvm_test.qemu.pid.XXXXX)
> +
> +cleanup() {
> +	rm -f "${perfdata}"
> +	if [ -f "${qemu_pid_file}" ]; then
> +		if [ -s "${qemu_pid_file}" ]; then
> +			qemu_pid=$(cat "${qemu_pid_file}")
> +			if [ -n "${qemu_pid}" ]; then
> +				kill "${qemu_pid}" 2>/dev/null || true
> +			fi
> +		fi
> +		rm -f "${qemu_pid_file}"
> +	fi
> +	trap - EXIT TERM INT
> +}
> +
> +trap_cleanup() {
> +	echo "Unexpected signal in ${FUNCNAME[1]}"
> +	cleanup
> +	exit 1
> +}
> +trap trap_cleanup EXIT TERM INT
> +
> +skip() {
> +	echo "Skip: $1"
> +	cleanup
> +	exit 2
> +}
> +
> +test_kvm_stat() {
> +	echo "Testing perf kvm stat"
> +
> +	echo "Recording kvm events for pid ${qemu_pid}..."
> +	if ! perf kvm stat record -p "${qemu_pid}" -o "${perfdata}" sleep 1; then
> +		echo "Failed to record kvm events"
> +		err=1
> +		return
> +	fi
> +
> +	echo "Reporting kvm events..."
> +	if ! perf kvm -i "${perfdata}" stat report 2>&1 | grep -q "VM-EXIT"; then
> +		echo "Failed to find VM-EXIT in report"
> +		perf kvm -i "${perfdata}" stat report 2>&1
> +		err=1
> +		return
> +	fi
> +
> +	echo "perf kvm stat test [Success]"
> +}
> +
> +test_kvm_record_report() {
> +	echo "Testing perf kvm record/report"
> +
> +	echo "Recording kvm profile for pid ${qemu_pid}..."
> +	# Use --host to avoid needing guest symbols/mounts for this simple test
> +	# We just want to verify the command runs and produces data
> +	# We run in background and kill it because 'perf kvm record' appends options
> +	# after the command, which breaks 'sleep' (e.g. it gets '-e cycles').
> +	perf kvm --host record -p "${qemu_pid}" -o "${perfdata}" &
> +	rec_pid=$!
> +	sleep 1
> +	kill -INT "${rec_pid}"
> +	wait "${rec_pid}" || true
> +
> +	echo "Reporting kvm profile..."
> +	# Check for some standard output from report
> +	if ! perf kvm -i "${perfdata}" report --stdio 2>&1 | grep -q "Event count"; then
> +		echo "Failed to report kvm profile"
> +		perf kvm -i "${perfdata}" report --stdio 2>&1
> +		err=1
> +		return
> +	fi
> +
> +	echo "perf kvm record/report test [Success]"
> +}
> +
> +test_kvm_buildid_list() {
> +	echo "Testing perf kvm buildid-list"
> +
> +	# We reuse the perf.data from the previous record test
> +	if ! perf kvm --host -i "${perfdata}" buildid-list 2>&1 | grep -q "."; then
> +		echo "Failed to list buildids"
> +		perf kvm --host -i "${perfdata}" buildid-list 2>&1
> +		err=1
> +		return
> +	fi
> +
> +	echo "perf kvm buildid-list test [Success]"
> +}
> +
> +setup_qemu() {
> +	# Find qemu
> +	if [ "$(uname -m)" = "x86_64" ]; then
> +		qemu="qemu-system-x86_64"
> +	elif [ "$(uname -m)" = "aarch64" ]; then
> +		qemu="qemu-system-aarch64"
> +	elif [ "$(uname -m)" = "s390x" ]; then
> +		qemu="qemu-system-s390x"
> +	elif [ "$(uname -m)" = "ppc64le" ]; then
> +		qemu="qemu-system-ppc64"
> +	else
> +		qemu="qemu-system-$(uname -m)"
> +	fi
> +
> +	if ! which -s "$qemu"; then
> +		skip "$qemu not found"
> +	fi
> +
> +	if [ ! -r /dev/kvm ] || [ ! -w /dev/kvm ]; then
> +		skip "/dev/kvm not accessible"
> +	fi
> +
> +	if ! perf kvm stat record -a sleep 0.01 >/dev/null 2>&1; then
> +		skip "No permission to record kvm events"
> +	fi
> +
> +	echo "Starting $qemu..."
> +	# Start qemu in background, detached, with pidfile
> +	# We use -display none -daemonize and a monitor to keep it alive/controllable if needed
> +	# We don't need a real kernel, just KVM active.
> +	if ! $qemu -enable-kvm -display none -daemonize -pidfile "${qemu_pid_file}" -monitor none; then

What is running in the guest?

Thanks,
Namhyung


> +		echo "Failed to start qemu"
> +		err=1
> +		return
> +	fi
> +
> +	# Wait a bit for qemu to start
> +	sleep 1
> +	qemu_pid=$(cat "${qemu_pid_file}")
> +
> +	if ! kill -0 "${qemu_pid}" 2>/dev/null; then
> +		echo "Qemu process failed to stay alive"
> +		err=1
> +		return
> +	fi
> +}
> +
> +setup_qemu
> +if [ $err -eq 0 ]; then
> +	test_kvm_stat
> +	test_kvm_record_report
> +	test_kvm_buildid_list
> +fi
> +
> +cleanup
> +exit $err
> -- 
> 2.52.0.rc2.455.g230fcf2819-goog
>