qemu: Resolve issue with GetScheduler APIs for non running domain

As a consequence of the cgroup layout changes from commit '632f78ca', the
qemuDomainGetSchedulerParameters[Flags]()' and qemuGetSchedulerType() APIs
failed to return data for a non running domain.  This can be seen through
a 'virsh schedinfo <domain>' command which returns:

Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

Prior to that change a non running domain would return:

Scheduler      : posix
cpu_shares     : 0
vcpu_period    : 0
vcpu_quota     : 0
emulator_period: 0
emulator_quota : 0

This patch will restore the capability to return configuration only data
for a non running domain regardless of whether cgroups are available.
(cherry picked from commit b23754534193fb7a1e31306d94ae5f09759a0aa4)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 5ca0fd4a1eb741783c058b2326c46d1536a99d08..ebba21d848814db9b7706a341d9c2519794a12e0 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6903,6 +6903,14 @@ static char *qemuDomainGetSchedulerType(virDomainPtr dom,
     }
     priv = vm->privateData;
 
+    /* Domain not running, thus no cgroups - return defaults */
+    if (!virDomainObjIsActive(vm)) {
+        if (nparams)
+            *nparams = 5;
+        ignore_value(VIR_STRDUP(ret, "posix"));
+        goto cleanup;
+    }
+
     if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPU)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
                        "%s", _("cgroup CPU controller is not mounted"));
@@ -8315,11 +8323,12 @@ qemuDomainGetSchedulerParametersFlags(virDomainPtr dom,
 
     if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
         shares = persistentDef->cputune.shares;
-        if (*nparams > 1 && cpu_bw_status) {
+        if (*nparams > 1) {
             period = persistentDef->cputune.period;
             quota = persistentDef->cputune.quota;
             emulator_period = persistentDef->cputune.emulator_period;
             emulator_quota = persistentDef->cputune.emulator_quota;
+            cpu_bw_status = true; /* Allow copy of data to params[] */
         }
         goto out;
     }