* [PATCH net-next 1/2] selftests/vsock: fix vmtest.sh for read-only nested VM runners
2026-03-14 0:00 [PATCH net-next 0/2] selftests/vsock: support nested VM runner for vmtest.sh Bobby Eshleman
@ 2026-03-14 0:00 ` Bobby Eshleman
2026-03-17 14:46 ` Paolo Abeni
2026-03-14 0:00 ` [PATCH net-next 2/2] selftests/vsock: fix vsock_test path shadowing in nested VMs Bobby Eshleman
1 sibling, 1 reply; 5+ messages in thread
From: Bobby Eshleman @ 2026-03-14 0:00 UTC (permalink / raw)
To: Stefano Garzarella, Shuah Khan
Cc: virtualization, netdev, linux-kselftest, linux-kernel,
Jakub Kicinski, Bobby Eshleman
From: Bobby Eshleman <bobbyeshleman@meta.com>
When running vmtest.sh inside a nested VM, there occurs a problem
with stacking two sets of virtiofs/overlay layers (the first set from
the outer VM and the second set from the inner VM). The virtme init
scripts (sshd, udhcpd, etc...) fail to execute basic programs (e.g.,
/bin/cat) and load library dependencies (e.g., libpam) due to ESTALE.
This only occurs when both layers (outer and inner) use virtiofs. Work
around this by using 9p in the inner VM via --force-9p.
Additionally, when the outer VM is read-only, the inner VM's attempt at
populating SSH keys to the root filesystem fails:
virtme-ng-init: mkdir: cannot create directory '/root/.cache': Read-only file system
Work around this by creating a temporary home directory with generated
SSH keys and passing it through to the guest as /root via --rwdir.
Disable strict host key checking in vm_ssh() since the VM will be seen
as a new host each run.
The --rw arg had to be removed to prevent a vng complaint about overlay
(in combination with the other parameters). The guest doesn't really
need write access anyway, so this was probably overly permissive to
begin with.
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
tools/testing/selftests/vsock/vmtest.sh | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index 86e338886b33..c2cfcdf05d99 100755
--- a/tools/testing/selftests/vsock/vmtest.sh
+++ b/tools/testing/selftests/vsock/vmtest.sh
@@ -42,6 +42,8 @@ readonly KERNEL_CMDLINE="\
virtme.ssh virtme_ssh_channel=tcp virtme_ssh_user=$USER \
"
readonly LOG=$(mktemp /tmp/vsock_vmtest_XXXX.log)
+readonly TEST_HOME=$(mktemp -d /tmp/vmtest_home_XXXX)
+readonly SSH_KEY_PATH="${TEST_HOME}"/.ssh/id_ed25519
# Namespace tests must use the ns_ prefix. This is checked in check_netns() and
# is used to determine if a test needs namespace setup before test execution.
@@ -257,7 +259,12 @@ vm_ssh() {
shift
- ${ns_exec} ssh -q -o UserKnownHostsFile=/dev/null -p "${SSH_HOST_PORT}" localhost "$@"
+ ${ns_exec} ssh -q \
+ -i "${SSH_KEY_PATH}" \
+ -o UserKnownHostsFile=/dev/null \
+ -o StrictHostKeyChecking=no \
+ -p "${SSH_HOST_PORT}" \
+ localhost "$@"
return $?
}
@@ -265,6 +272,7 @@ vm_ssh() {
cleanup() {
terminate_pidfiles "${!PIDFILES[@]}"
del_namespaces
+ rm -rf "${TEST_HOME}"
}
check_args() {
@@ -382,6 +390,11 @@ handle_build() {
popd &>/dev/null
}
+setup_home() {
+ mkdir -p "$(dirname "${SSH_KEY_PATH}")"
+ ssh-keygen -t ed25519 -f "${SSH_KEY_PATH}" -N "" -q
+}
+
create_pidfile() {
local pidfile
@@ -451,11 +464,14 @@ vm_start() {
--run \
${kernel_opt} \
${verbose_opt} \
+ --rwdir=/root=${TEST_HOME} \
+ --force-9p \
+ --cwd /root \
--qemu-opts="${qemu_opts}" \
--qemu="${qemu}" \
--user root \
--append "${KERNEL_CMDLINE}" \
- --rw &> ${logfile} &
+ &> ${logfile} &
timeout "${WAIT_QEMU}" \
bash -c 'while [[ ! -s '"${pidfile}"' ]]; do sleep 1; done; exit 0'
@@ -1532,6 +1548,7 @@ check_deps
check_vng
check_socat
handle_build
+setup_home
echo "1..${#ARGS[@]}"
--
2.52.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH net-next 2/2] selftests/vsock: fix vsock_test path shadowing in nested VMs
2026-03-14 0:00 [PATCH net-next 0/2] selftests/vsock: support nested VM runner for vmtest.sh Bobby Eshleman
2026-03-14 0:00 ` [PATCH net-next 1/2] selftests/vsock: fix vmtest.sh for read-only nested VM runners Bobby Eshleman
@ 2026-03-14 0:00 ` Bobby Eshleman
1 sibling, 0 replies; 5+ messages in thread
From: Bobby Eshleman @ 2026-03-14 0:00 UTC (permalink / raw)
To: Stefano Garzarella, Shuah Khan
Cc: virtualization, netdev, linux-kselftest, linux-kernel,
Jakub Kicinski, Bobby Eshleman
From: Bobby Eshleman <bobbyeshleman@meta.com>
The /root mount introduced for nested VM support shadows any host paths
under /root. This breaks systems where the outer VM runs as root and the
vsock_test binary path is something like:
/root/linux/tools/testing/selftests/vsock/vsock_test
Fix this by copying vsock_test into the temporary home directory that
gets mounted as /root in the guest, and using a relative path to invoke
it.
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
tools/testing/selftests/vsock/vmtest.sh | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index c2cfcdf05d99..8182c748f214 100755
--- a/tools/testing/selftests/vsock/vmtest.sh
+++ b/tools/testing/selftests/vsock/vmtest.sh
@@ -393,6 +393,7 @@ handle_build() {
setup_home() {
mkdir -p "$(dirname "${SSH_KEY_PATH}")"
ssh-keygen -t ed25519 -f "${SSH_KEY_PATH}" -N "" -q
+ cp "${VSOCK_TEST}" "${TEST_HOME}"/vsock_test
}
create_pidfile() {
@@ -601,7 +602,7 @@ vm_vsock_test() {
# log output and use pipefail to respect vsock_test errors
set -o pipefail
if [[ "${host}" != server ]]; then
- vm_ssh "${ns}" -- "${VSOCK_TEST}" \
+ vm_ssh "${ns}" -- ./vsock_test \
--mode=client \
--control-host="${host}" \
--peer-cid="${cid}" \
@@ -609,7 +610,7 @@ vm_vsock_test() {
2>&1 | log_guest
rc=$?
else
- vm_ssh "${ns}" -- "${VSOCK_TEST}" \
+ vm_ssh "${ns}" -- ./vsock_test \
--mode=server \
--peer-cid="${cid}" \
--control-port="${port}" \
--
2.52.0
^ permalink raw reply related [flat|nested] 5+ messages in thread