From: Peter Krempa <pkrempa@redhat.com>

The 'set-action' QMP command was introduced in qemu-6.0 and can't be
disabled in any way. Oldest qemu we support is qemu-7.2 so all versions
now have it.

Remove all conditional code which depends on the 'set-action' command.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 src/qemu/qemu_command.c  | 13 +++----------
 src/qemu/qemu_driver.c   | 16 ----------------
 src/qemu/qemu_hotplug.c  | 10 +---------
 src/qemu/qemu_process.c  | 31 +------------------------------
 src/qemu/qemu_validate.c | 14 ++------------
 5 files changed, 7 insertions(+), 77 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 95e2ea9a6b..a76a034158 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6184,16 +6184,9 @@ qemuBuildPMCommandLine(virCommand *cmd,
 {
     virQEMUCaps *qemuCaps = priv->qemuCaps;

-    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION)) {
-        /* with new qemu we always want '-no-shutdown' on startup and we set
-         * all the other behaviour later during startup */
-        virCommandAddArg(cmd, "-no-shutdown");
-    } else {
-        if (priv->allowReboot == VIR_TRISTATE_BOOL_NO)
-            virCommandAddArg(cmd, "-no-reboot");
-        else
-            virCommandAddArg(cmd, "-no-shutdown");
-    }
+    /* with new qemu we always want '-no-shutdown' on startup and we set
+     * all the other behaviour later during startup */
+    virCommandAddArg(cmd, "-no-shutdown");

     /* Use old syntax of -no-acpi only if qemu didn't report that it supports the
      * new syntax */
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index bdc0cff66a..71308770f6 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -19548,9 +19548,6 @@ qemuDomainModifyLifecycleActionLive(virDomainObj *vm,
     qemuDomainObjPrivate *priv = vm->privateData;
     int rc;

-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION))
-        return 0;
-
     /* For now we only update 'reboot' action here as we want to keep the
      * shutdown action as is (we're emulating the outcome anyways)) */
     if (type != VIR_DOMAIN_LIFECYCLE_REBOOT ||
@@ -19600,7 +19597,6 @@ qemuDomainSetLifecycleAction(virDomainPtr dom,
 {
     virQEMUDriver *driver = dom->conn->privateData;
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
-    qemuDomainObjPrivate *priv;
     virDomainObj *vm = NULL;
     virDomainDef *def = NULL;
     virDomainDef *persistentDef = NULL;
@@ -19617,8 +19613,6 @@ qemuDomainSetLifecycleAction(virDomainPtr dom,
     if (!(vm = qemuDomainObjFromDomain(dom)))
         goto cleanup;

-    priv = vm->privateData;
-
     if (virDomainSetLifecycleActionEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;

@@ -19633,16 +19627,6 @@ qemuDomainSetLifecycleAction(virDomainPtr dom,
         goto endjob;

     if (def) {
-        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION)) {
-            if (priv->allowReboot == VIR_TRISTATE_BOOL_NO ||
-                (type == VIR_DOMAIN_LIFECYCLE_REBOOT &&
-                 def->onReboot != action)) {
-                virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                               _("cannot update lifecycle action because QEMU was started with incompatible -no-reboot setting"));
-                goto endjob;
-            }
-        }
-
         if (qemuDomainModifyLifecycleActionLive(vm, type, action) < 0)
             goto endjob;

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 5be567b510..8990a716fa 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -3061,7 +3061,7 @@ qemuDomainAttachWatchdog(virDomainObj *vm,
     if (vm->def->nwatchdogs) {
         /* Domain already has a watchdog and all must have the same action. */
         rv = 0;
-    } else if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION)) {
+    } else {
         /* QEMU doesn't have a 'dump' action; we tell qemu to 'pause', then
            libvirt listens for the watchdog event, and we perform the dump
            ourselves. so convert 'dump' to 'pause' for the qemu cli */
@@ -3103,14 +3103,6 @@ qemuDomainAttachWatchdog(virDomainObj *vm,
                                   QEMU_MONITOR_ACTION_REBOOT_KEEP,
                                   watchdogaction,
                                   QEMU_MONITOR_ACTION_PANIC_KEEP);
-    } else {
-        virDomainWatchdogAction actualAction = watchdog->action;
-
-        if (actualAction == VIR_DOMAIN_WATCHDOG_ACTION_DUMP)
-            actualAction = VIR_DOMAIN_WATCHDOG_ACTION_PAUSE;
-
-        rv = qemuMonitorSetWatchdogAction(priv->mon,
-                                          virDomainWatchdogActionTypeToString(actualAction));
     }

     if (rv >= 0)
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 4c94ff3c91..646ddda7e9 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6898,24 +6898,6 @@ qemuProcessRebootAllowed(const virDomainDef *def)
 }


-static void
-qemuProcessPrepareAllowReboot(virDomainObj *vm)
-{
-    virDomainDef *def = vm->def;
-    qemuDomainObjPrivate *priv = vm->privateData;
-
-    /* with 'set-action' QMP command we don't need to keep this around as
-     * we always update qemu with the proper state */
-    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION))
-        return;
-
-    if (priv->allowReboot != VIR_TRISTATE_BOOL_ABSENT)
-        return;
-
-    priv->allowReboot = virTristateBoolFromBool(qemuProcessRebootAllowed(def));
-}
-
-
 static int
 qemuProcessUpdateSEVInfo(virDomainObj *vm)
 {
@@ -7087,8 +7069,6 @@ qemuProcessPrepareDomain(virQEMUDriver *driver,
     /* Track if this domain remembers original owner */
     priv->rememberOwner = cfg->rememberOwner;

-    qemuProcessPrepareAllowReboot(vm);
-
     /*
      * Normally PCI addresses are assigned in the virDomainCreate
      * or virDomainDefine methods. We might still need to assign
@@ -8216,9 +8196,6 @@ qemuProcessSetupLifecycleActions(virDomainObj *vm,
     qemuDomainObjPrivate *priv = vm->privateData;
     int rc;

-    if (!(virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION)))
-        return 0;
-
     /* for now we handle only onReboot->destroy here as an alternative to
      * '-no-reboot' on the commandline */
     if (vm->def->onReboot != VIR_DOMAIN_LIFECYCLE_ACTION_DESTROY)
@@ -9909,10 +9886,6 @@ qemuProcessReconnect(void *opaque)
     if (qemuExtDevicesInitPaths(cfg, obj->def) < 0)
         goto error;

-    /* If we are connecting to a guest started by old libvirt there is no
-     * allowReboot in status XML and we need to initialize it. */
-    qemuProcessPrepareAllowReboot(obj);
-
     if (qemuHostdevUpdateActiveDomainDevices(driver, obj->def) < 0)
         goto error;

@@ -10147,9 +10120,7 @@ qemuProcessReconnect(void *opaque)
          * domain crashed; otherwise, if the monitor was started,
          * then we can blame ourselves, else we failed before the
          * monitor started so we don't really know. */
-        if (!priv->mon && tryMonReconn &&
-            (priv->allowReboot == VIR_TRISTATE_BOOL_YES ||
-             virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SET_ACTION)))
+        if (!priv->mon && tryMonReconn)
             state = VIR_DOMAIN_SHUTOFF_CRASHED;
         else if (priv->mon)
             state = VIR_DOMAIN_SHUTOFF_DAEMON;
diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index 439d4b1916..ae1edf435a 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -3658,10 +3658,7 @@ qemuValidateDomainDeviceDefDiskBlkdeviotune(const virDomainDiskDef *disk,


 static int
-qemuValidateDomainDeviceDefDiskTransient(const virDomainDiskDef *disk,
-                                         const virDomainDef *def,
-                                         virQEMUCaps *qemuCaps)
-
+qemuValidateDomainDeviceDefDiskTransient(const virDomainDiskDef *disk)
 {
     virStorageType actualType = virStorageSourceGetActualType(disk->src);

@@ -3695,13 +3692,6 @@ qemuValidateDomainDeviceDefDiskTransient(const virDomainDiskDef *disk,
     }

     if (disk->transientShareBacking == VIR_TRISTATE_BOOL_YES) {
-        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_SET_ACTION) &&
-            !qemuProcessRebootAllowed(def)) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                           _("transient disk backing image sharing with destroy action of lifecycle isn't supported by this QEMU binary"));
-            return -1;
-        }
-
         /* sharing the backing file requires hotplug of the disk in the qemu driver */
         switch (disk->bus) {
         case VIR_DOMAIN_DISK_BUS_USB:
@@ -3747,7 +3737,7 @@ qemuValidateDomainDeviceDefDisk(const virDomainDiskDef *disk,
     if (qemuValidateDomainDeviceDefDiskBlkdeviotune(disk, def) < 0)
         return -1;

-    if (qemuValidateDomainDeviceDefDiskTransient(disk, def, qemuCaps) < 0)
+    if (qemuValidateDomainDeviceDefDiskTransient(disk) < 0)
         return -1;

     if (disk->src->shared && !disk->src->readonly &&
-- 
2.55.0

On a Wednesday in 2026, Peter Krempa via Devel wrote:
>From: Peter Krempa <pkrempa@redhat.com>
>
>The 'set-action' QMP command was introduced in qemu-6.0 and can't be
>disabled in any way. Oldest qemu we support is qemu-7.2 so all versions
>now have it.
>
>Remove all conditional code which depends on the 'set-action' command.
>
>Signed-off-by: Peter Krempa <pkrempa@redhat.com>
>---
> src/qemu/qemu_command.c  | 13 +++----------
> src/qemu/qemu_driver.c   | 16 ----------------
> src/qemu/qemu_hotplug.c  | 10 +---------
> src/qemu/qemu_process.c  | 31 +------------------------------
> src/qemu/qemu_validate.c | 14 ++------------
> 5 files changed, 7 insertions(+), 77 deletions(-)
>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

Jano