vcontainer: add QEMU hypervisor backend and register in recipes

Add vrunner-backend-qemu.sh implementing the hypervisor interface for
QEMU (arch setup, KVM detection, disk/network/9p options, VM lifecycle,
QMP control). Register backend scripts in vcontainer-native and
vcontainer-tarball recipes so they are available in both build-time
and standalone tarball contexts.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

1 files changed, 260 insertions, 0 deletions

diff --git a/recipes-containers/vcontainer/files/vrunner-backend-qemu.sh b/recipes-containers/vcontainer/files/vrunner-backend-qemu.sh
new file mode 100644
index 00000000..87054876
--- /dev/null
+++ b/recipes-containers/vcontainer/files/vrunner-backend-qemu.sh
@@ -0,0 +1,260 @@
+#!/bin/bash
+# SPDX-FileCopyrightText: Copyright (C) 2025 Bruce Ashfield
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# vrunner-backend-qemu.sh
+# QEMU hypervisor backend for vrunner.sh
+#
+# This backend implements the hypervisor interface for QEMU.
+# It is sourced by vrunner.sh when VCONTAINER_HYPERVISOR=qemu.
+#
+# Backend interface functions:
+#   hv_setup_arch()            - Set arch-specific QEMU command and machine type
+#   hv_check_accel()           - Detect KVM acceleration
+#   hv_build_disk_opts()       - Build QEMU disk drive options
+#   hv_build_network_opts()    - Build QEMU network options
+#   hv_build_9p_opts()         - Build QEMU virtio-9p options
+#   hv_build_daemon_opts()     - Build QEMU daemon mode options (serial, QMP)
+#   hv_build_vm_cmd()          - Assemble final QEMU command line
+#   hv_start_vm_background()   - Start QEMU in background, capture PID
+#   hv_start_vm_foreground()   - Start QEMU in foreground (interactive)
+#   hv_is_vm_running()         - Check if QEMU process is alive
+#   hv_wait_vm_exit()          - Wait for QEMU to exit
+#   hv_stop_vm()               - Graceful shutdown via QMP
+#   hv_destroy_vm()            - Force kill QEMU process
+#   hv_get_vm_id()             - Return QEMU PID
+#   hv_setup_port_forwards()   - Port forwards via QEMU hostfwd (built into netdev)
+#   hv_cleanup_port_forwards() - No-op for QEMU (forwards die with process)
+#   hv_idle_shutdown()         - Send QMP quit for idle timeout
+#   hv_get_console_device()    - Return arch-specific console device name
+
+# ============================================================================
+# Architecture Setup
+# ============================================================================
+
+hv_setup_arch() {
+    case "$TARGET_ARCH" in
+        aarch64)
+            KERNEL_IMAGE="$BLOB_DIR/aarch64/Image"
+            INITRAMFS="$BLOB_DIR/aarch64/initramfs.cpio.gz"
+            ROOTFS_IMG="$BLOB_DIR/aarch64/rootfs.img"
+            HV_CMD="qemu-system-aarch64"
+            HV_MACHINE="-M virt -cpu cortex-a57"
+            HV_CONSOLE="ttyAMA0"
+            ;;
+        x86_64)
+            KERNEL_IMAGE="$BLOB_DIR/x86_64/bzImage"
+            INITRAMFS="$BLOB_DIR/x86_64/initramfs.cpio.gz"
+            ROOTFS_IMG="$BLOB_DIR/x86_64/rootfs.img"
+            HV_CMD="qemu-system-x86_64"
+            HV_MACHINE="-M q35 -cpu Skylake-Client"
+            HV_CONSOLE="ttyS0"
+            ;;
+        *)
+            log "ERROR" "Unsupported architecture: $TARGET_ARCH"
+            exit 1
+            ;;
+    esac
+}
+
+hv_check_accel() {
+    USE_KVM="false"
+    if [ "$DISABLE_KVM" = "true" ]; then
+        log "DEBUG" "KVM disabled by --no-kvm flag"
+        return
+    fi
+
+    HOST_ARCH=$(uname -m)
+    if [ "$HOST_ARCH" = "$TARGET_ARCH" ] || \
+       { [ "$HOST_ARCH" = "x86_64" ] && [ "$TARGET_ARCH" = "x86_64" ]; }; then
+        if [ -w /dev/kvm ]; then
+            USE_KVM="true"
+            case "$TARGET_ARCH" in
+                x86_64)  HV_MACHINE="-M q35 -cpu host" ;;
+                aarch64) HV_MACHINE="-M virt -cpu host" ;;
+            esac
+            log "INFO" "KVM acceleration enabled"
+        else
+            log "DEBUG" "KVM not available (no write access to /dev/kvm)"
+        fi
+    fi
+}
+
+hv_find_command() {
+    if ! command -v "$HV_CMD" >/dev/null 2>&1; then
+        for path in \
+            "${STAGING_BINDIR_NATIVE:-}" \
+            "/usr/bin"; do
+            if [ -n "$path" ] && [ -x "$path/$HV_CMD" ]; then
+                HV_CMD="$path/$HV_CMD"
+                break
+            fi
+        done
+    fi
+
+    if ! command -v "$HV_CMD" >/dev/null 2>&1 && [ ! -x "$HV_CMD" ]; then
+        log "ERROR" "QEMU not found: $HV_CMD"
+        exit 1
+    fi
+    log "DEBUG" "Using QEMU: $HV_CMD"
+}
+
+hv_get_console_device() {
+    echo "$HV_CONSOLE"
+}
+
+# ============================================================================
+# VM Configuration Building
+# ============================================================================
+
+hv_build_disk_opts() {
+    # Rootfs (read-only)
+    HV_DISK_OPTS="-drive file=$ROOTFS_IMG,if=virtio,format=raw,readonly=on"
+
+    # Input disk (if any)
+    if [ -n "$DISK_OPTS" ]; then
+        HV_DISK_OPTS="$HV_DISK_OPTS $DISK_OPTS"
+    fi
+
+    # State disk (if any)
+    if [ -n "$STATE_DISK_OPTS" ]; then
+        HV_DISK_OPTS="$HV_DISK_OPTS $STATE_DISK_OPTS"
+    fi
+}
+
+hv_build_network_opts() {
+    HV_NET_OPTS=""
+    if [ "$NETWORK" = "true" ]; then
+        NETDEV_OPTS="user,id=net0"
+
+        # Add port forwards
+        for pf in "${PORT_FORWARDS[@]}"; do
+            HOST_PORT="${pf%%:*}"
+            CONTAINER_PART="${pf#*:}"
+            CONTAINER_PORT="${CONTAINER_PART%%/*}"
+            if [[ "$CONTAINER_PART" == */* ]]; then
+                PROTOCOL="${CONTAINER_PART##*/}"
+            else
+                PROTOCOL="tcp"
+            fi
+            NETDEV_OPTS="$NETDEV_OPTS,hostfwd=$PROTOCOL::$HOST_PORT-:$HOST_PORT"
+            log "INFO" "Port forward: host:$HOST_PORT -> VM:$HOST_PORT (Docker maps to container:$CONTAINER_PORT)"
+        done
+
+        HV_NET_OPTS="-netdev $NETDEV_OPTS -device virtio-net-pci,netdev=net0"
+    else
+        HV_NET_OPTS="-nic none"
+    fi
+}
+
+hv_build_9p_opts() {
+    local share_dir="$1"
+    local share_tag="$2"
+    local extra_opts="${3:-}"
+    HV_OPTS="$HV_OPTS -virtfs local,path=$share_dir,mount_tag=$share_tag,security_model=none${extra_opts:+,$extra_opts},id=$share_tag"
+}
+
+hv_build_daemon_opts() {
+    HV_DAEMON_OPTS=""
+
+    # virtio-serial for command channel
+    HV_DAEMON_OPTS="$HV_DAEMON_OPTS -chardev socket,id=vdkr,path=$DAEMON_SOCKET,server=on,wait=off"
+    HV_DAEMON_OPTS="$HV_DAEMON_OPTS -device virtio-serial-pci"
+    HV_DAEMON_OPTS="$HV_DAEMON_OPTS -device virtserialport,chardev=vdkr,name=vdkr"
+
+    # QMP socket for dynamic control
+    QMP_SOCKET="$DAEMON_SOCKET_DIR/qmp.sock"
+    HV_DAEMON_OPTS="$HV_DAEMON_OPTS -qmp unix:$QMP_SOCKET,server,nowait"
+}
+
+hv_build_vm_cmd() {
+    HV_OPTS="$HV_MACHINE -nographic -smp 2 -m 2048 -no-reboot"
+    if [ "$USE_KVM" = "true" ]; then
+        HV_OPTS="$HV_OPTS -enable-kvm"
+    fi
+    HV_OPTS="$HV_OPTS -kernel $KERNEL_IMAGE"
+    HV_OPTS="$HV_OPTS -initrd $INITRAMFS"
+    HV_OPTS="$HV_OPTS $HV_DISK_OPTS"
+    HV_OPTS="$HV_OPTS $HV_NET_OPTS"
+}
+
+# ============================================================================
+# VM Lifecycle
+# ============================================================================
+
+hv_start_vm_background() {
+    local kernel_append="$1"
+    local log_file="$2"
+    local timeout_val="$3"
+
+    if [ -n "$timeout_val" ]; then
+        timeout $timeout_val $HV_CMD $HV_OPTS -append "$kernel_append" > "$log_file" 2>&1 &
+    else
+        $HV_CMD $HV_OPTS -append "$kernel_append" > "$log_file" 2>&1 &
+    fi
+    HV_VM_PID=$!
+}
+
+hv_start_vm_foreground() {
+    local kernel_append="$1"
+    $HV_CMD $HV_OPTS -append "$kernel_append"
+}
+
+hv_is_vm_running() {
+    [ -n "$HV_VM_PID" ] && [ -d "/proc/$HV_VM_PID" ]
+}
+
+hv_wait_vm_exit() {
+    local timeout="${1:-30}"
+    for i in $(seq 1 "$timeout"); do
+        hv_is_vm_running || return 0
+        sleep 1
+    done
+    return 1
+}
+
+hv_stop_vm() {
+    if [ -n "$HV_VM_PID" ] && kill -0 "$HV_VM_PID" 2>/dev/null; then
+        log "WARN" "QEMU still running, forcing termination..."
+        kill $HV_VM_PID 2>/dev/null || true
+        wait $HV_VM_PID 2>/dev/null || true
+    fi
+}
+
+hv_destroy_vm() {
+    if [ -n "$HV_VM_PID" ]; then
+        kill -9 $HV_VM_PID 2>/dev/null || true
+        wait $HV_VM_PID 2>/dev/null || true
+    fi
+}
+
+hv_get_vm_id() {
+    echo "$HV_VM_PID"
+}
+
+# ============================================================================
+# Port Forwarding (handled by QEMU hostfwd, no separate setup needed)
+# ============================================================================
+
+hv_setup_port_forwards() {
+    # QEMU port forwards are built into the -netdev hostfwd= options
+    # Nothing extra to do at runtime
+    :
+}
+
+hv_cleanup_port_forwards() {
+    # QEMU port forwards die with the process
+    :
+}
+
+# ============================================================================
+# Idle Timeout / QMP Control
+# ============================================================================
+
+hv_idle_shutdown() {
+    if [ -S "$QMP_SOCKET" ]; then
+        echo '{"execute":"qmp_capabilities"}{"execute":"quit"}' | \
+            socat - "UNIX-CONNECT:$QMP_SOCKET" >/dev/null 2>&1 || true
+    fi
+}