hypervisor: expand available shutdown actions

The auto shutdown code can currently only perform managed save,
which may fail in some cases, for example when PCI devices are
assigned. On failure, shutdown inhibitors remain in place which
may be undesirable.

This expands the logic to try a sequence of operations

 * Managed save
 * Graceful shutdown
 * Forced poweroff

Each of these operations can be enabled or disabled, but they
are always applied in this order.

With the shutdown option, a configurable time is allowed for
shutdown to complete, defaulting to 30 seconds, before moving
onto the forced poweroff phase.

Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/hypervisor/domain_driver.c

@@ -721,9 +721,25 @@ virDomainDriverAutoShutdown(virDomainDriverAutoShutdownConfig *cfg)
     g_autoptr(virConnect) conn = NULL;
     int numDomains = 0;
     size_t i;
-    int state;
     virDomainPtr *domains = NULL;
-    g_autofree unsigned int *flags = NULL;
+
+    VIR_DEBUG("Run autoshutdown uri=%s trySave=%d tryShutdown=%d poweroff=%d waitShutdownSecs=%u",
+              cfg->uri, cfg->trySave, cfg->tryShutdown, cfg->poweroff,
+              cfg->waitShutdownSecs);
+
+    /*
+     * Ideally guests will shutdown in a few seconds, but it would
+     * not be unsual for it to take a while longer, especially under
+     * load, or if the guest OS has inhibitors slowing down shutdown.
+     *
+     * If we wait too long, then guests which ignore the shutdown
+     * request will significantly delay host shutdown.
+     *
+     * Pick 30 seconds as a moderately safe default, assuming that
+     * most guests are well behaved.
+     */
+    if (cfg->waitShutdownSecs <= 0)
+        cfg->waitShutdownSecs = 30;
 
     if (!(conn = virConnectOpen(cfg->uri)))
         goto cleanup;
@@ -733,31 +749,107 @@ virDomainDriverAutoShutdown(virDomainDriverAutoShutdownConfig *cfg)
                                                VIR_CONNECT_LIST_DOMAINS_ACTIVE)) < 0)
         goto cleanup;
 
-    flags = g_new0(unsigned int, numDomains);
-
-    /* First we pause all VMs to make them stop dirtying
-       pages, etc. We remember if any VMs were paused so
-       we can restore that on resume. */
-    for (i = 0; i < numDomains; i++) {
-        flags[i] = VIR_DOMAIN_SAVE_RUNNING;
-        if (virDomainGetState(domains[i], &state, NULL, 0) == 0) {
-            if (state == VIR_DOMAIN_PAUSED)
-                flags[i] = VIR_DOMAIN_SAVE_PAUSED;
+    VIR_DEBUG("Auto shutdown with %d running domains", numDomains);
+    if (cfg->trySave) {
+        g_autofree unsigned int *flags = g_new0(unsigned int, numDomains);
+        for (i = 0; i < numDomains; i++) {
+            int state;
+            /*
+             * Pause all VMs to make them stop dirtying pages,
+             * so save is quicker. We remember if any VMs were
+             * paused so we can restore that on resume.
+             */
+            flags[i] = VIR_DOMAIN_SAVE_RUNNING;
+            if (virDomainGetState(domains[i], &state, NULL, 0) == 0) {
+                if (state == VIR_DOMAIN_PAUSED)
+                    flags[i] = VIR_DOMAIN_SAVE_PAUSED;
+            }
+            if (flags[i] & VIR_DOMAIN_SAVE_RUNNING)
+                virDomainSuspend(domains[i]);
+        }
+
+        for (i = 0; i < numDomains; i++) {
+            if (virDomainManagedSave(domains[i], flags[i]) < 0) {
+                VIR_WARN("auto-shutdown: unable to perform managed save of '%s': %s",
+                         domains[i]->name,
+                         virGetLastErrorMessage());
+                if (flags[i] & VIR_DOMAIN_SAVE_RUNNING)
+                    virDomainResume(domains[i]);
+                continue;
+            }
+            virObjectUnref(domains[i]);
+            domains[i] = NULL;
         }
-        virDomainSuspend(domains[i]);
     }
 
-    /* Then we save the VMs to disk */
-    for (i = 0; i < numDomains; i++)
-        if (virDomainManagedSave(domains[i], flags[i]) < 0)
-            VIR_WARN("Unable to perform managed save of '%s': %s",
-                     virDomainGetName(domains[i]),
-                     virGetLastErrorMessage());
+    if (cfg->tryShutdown) {
+        GTimer *timer = NULL;
+        for (i = 0; i < numDomains; i++) {
+            if (domains[i] == NULL)
+                continue;
+            if (virDomainShutdown(domains[i]) < 0) {
+                VIR_WARN("auto-shutdown: unable to request graceful shutdown of '%s': %s",
+                         domains[i]->name,
+                         virGetLastErrorMessage());
+                break;
+            }
+        }
+
+        timer = g_timer_new();
+        while (1) {
+            bool anyRunning = false;
+            for (i = 0; i < numDomains; i++) {
+                if (!domains[i])
+                    continue;
+
+                if (virDomainIsActive(domains[i]) == 1) {
+                    anyRunning = true;
+                } else {
+                    virObjectUnref(domains[i]);
+                    domains[i] = NULL;
+                }
+            }
+
+            if (!anyRunning)
+                break;
+            if (g_timer_elapsed(timer, NULL) > cfg->waitShutdownSecs)
+                break;
+            g_usleep(1000*500);
+        }
+        g_timer_destroy(timer);
+    }
+
+    if (cfg->poweroff) {
+        for (i = 0; i < numDomains; i++) {
+            if (domains[i] == NULL)
+                continue;
+            /*
+             * NB might fail if we gave up on waiting for
+             * virDomainShutdown, but it then completed anyway,
+             * hence we're not checking for failure
+             */
+            virDomainDestroy(domains[i]);
+
+            virObjectUnref(domains[i]);
+            domains[i] = NULL;
+        }
+    }
 
  cleanup:
     if (domains) {
-        for (i = 0; i < numDomains; i++)
+        /* Anything non-NULL in this list indicates none of
+         * the configured ations were successful in processing
+         * the domain. There's not much we can do about that
+         * as the host is powering off, logging at least lets
+         * admins know
+         */
+        for (i = 0; i < numDomains; i++) {
+            if (domains[i] == NULL)
+                continue;
+            VIR_WARN("auto-shutdown: domain '%s' not successfully shut off by any action",
+                     domains[i]->name);
             virObjectUnref(domains[i]);
+        }
         VIR_FREE(domains);
     }
 }

src/hypervisor/domain_driver.h

@@ -93,6 +93,13 @@ void virDomainDriverAutoStart(virDomainObjList *domains,
 
 typedef struct _virDomainDriverAutoShutdownConfig {
     const char *uri;
+    bool trySave;
+    bool tryShutdown;
+    bool poweroff;
+    unsigned int waitShutdownSecs; /* Seconds to wait for VM to shutdown
+                                    * before moving onto next action.
+                                    * If 0 a default is used (currently 30 secs)
+                                    */
 } virDomainDriverAutoShutdownConfig;
 
 void virDomainDriverAutoShutdown(virDomainDriverAutoShutdownConfig *cfg);

src/qemu/qemu_driver.c

@@ -966,6 +966,9 @@ qemuStateStop(void)
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(qemu_driver);
     virDomainDriverAutoShutdownConfig ascfg = {
         .uri = cfg->uri,
+        .trySave = true,
+        .tryShutdown = false,
+        .poweroff = false,
     };
 
     if (!qemu_driver->privileged)