qemu: Reject unsupported tuning in session mode

When domain is started with setting that cannot be done, i.e. those
that require cgroups, there is no error reported and it succeeds
without any message whatsoever.

When setting with API, virsh, an error is reported, but only due to
the fact that no cgroups are mounted (priv->cgroup == NULL).

Given the above it seems reasonable to reject such unsupported
settings.

This patch effectively changes the error message from:

$ virsh -c qemu:///session schedinfo dummy
Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

to:

$ virsh -c qemu:///session schedinfo dummy
Scheduler      : Unknown
error: Operation not supported: CPU tuning is not available in session mode

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1023366

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_command.c

@@ -7762,6 +7762,32 @@ qemuBuildCommandLine(virConnectPtr conn,
 
     emulator = def->emulator;
 
+    if (!cfg->privileged) {
+        /* If we have no cgroups than we can have no tunings that
+         * require them */
+
+        if (def->mem.hard_limit || def->mem.soft_limit ||
+            def->mem.min_guarantee || def->mem.swap_hard_limit) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Memory tuning is not available in session mode"));
+            goto error;
+        }
+
+        if (def->blkio.weight || def->blkio.ndevices) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Block I/O tuning is not available in session mode"));
+            goto error;
+        }
+
+        if (def->cputune.shares || def->cputune.period ||
+            def->cputune.quota || def->cputune.emulator_period ||
+            def->cputune.emulator_quota) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("CPU tuning is not available in session mode"));
+            goto error;
+        }
+    }
+
     for (i = 0; i < def->ngraphics; ++i) {
         switch (def->graphics[i]->type) {
         case VIR_DOMAIN_GRAPHICS_TYPE_SDL:

src/qemu/qemu_driver.c

@@ -7432,6 +7432,8 @@ static char *qemuDomainGetSchedulerType(virDomainPtr dom,
     char *ret = NULL;
     virDomainObjPtr vm = NULL;
     qemuDomainObjPrivatePtr priv;
+    virQEMUDriverPtr driver = dom->conn->privateData;
+    virQEMUDriverConfigPtr cfg = NULL;
 
     if (!(vm = qemuDomObjFromDomain(dom)))
         goto cleanup;
@@ -7441,6 +7443,13 @@ static char *qemuDomainGetSchedulerType(virDomainPtr dom,
     if (virDomainGetSchedulerTypeEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("CPU tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     /* Domain not running, thus no cgroups - return defaults */
     if (!virDomainObjIsActive(vm)) {
         if (nparams)
@@ -7467,6 +7476,7 @@ static char *qemuDomainGetSchedulerType(virDomainPtr dom,
 cleanup:
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(cfg);
     return ret;
 }
 
@@ -7681,6 +7691,12 @@ qemuDomainSetBlkioParameters(virDomainPtr dom,
     if (virDomainSetBlkioParametersEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Block I/O tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -7861,6 +7877,7 @@ qemuDomainGetBlkioParameters(virDomainPtr dom,
     int ret = -1;
     virCapsPtr caps = NULL;
     qemuDomainObjPrivatePtr priv;
+    virQEMUDriverConfigPtr cfg = NULL;
 
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG |
@@ -7879,6 +7896,13 @@ qemuDomainGetBlkioParameters(virDomainPtr dom,
     if (virDomainGetBlkioParametersEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Block I/O tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -8267,6 +8291,7 @@ cleanup:
     if (vm)
         virObjectUnlock(vm);
     virObjectUnref(caps);
+    virObjectUnref(cfg);
     return ret;
 }
 
@@ -8314,6 +8339,12 @@ qemuDomainSetMemoryParameters(virDomainPtr dom,
     if (virDomainSetMemoryParametersEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("Memory tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -8421,6 +8452,7 @@ qemuDomainGetMemoryParameters(virDomainPtr dom,
     int ret = -1;
     virCapsPtr caps = NULL;
     qemuDomainObjPrivatePtr priv;
+    virQEMUDriverConfigPtr cfg = NULL;
 
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG |
@@ -8437,6 +8469,13 @@ qemuDomainGetMemoryParameters(virDomainPtr dom,
     if (virDomainGetMemoryParametersEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("Memory tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -8548,6 +8587,7 @@ cleanup:
     if (vm)
         virObjectUnlock(vm);
     virObjectUnref(caps);
+    virObjectUnref(cfg);
     return ret;
 }
 
@@ -8973,6 +9013,13 @@ qemuDomainSetSchedulerParametersFlags(virDomainPtr dom,
     if (virDomainSetSchedulerParametersFlagsEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("CPU tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -9208,6 +9255,7 @@ qemuDomainGetSchedulerParametersFlags(virDomainPtr dom,
     virDomainDefPtr persistentDef;
     virCapsPtr caps = NULL;
     qemuDomainObjPrivatePtr priv;
+    virQEMUDriverConfigPtr cfg = NULL;
 
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG |
@@ -9224,6 +9272,13 @@ qemuDomainGetSchedulerParametersFlags(virDomainPtr dom,
     if (virDomainGetSchedulerParametersFlagsEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("CPU tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (*nparams > 1)
         cpu_bw_status = virCgroupSupportsCpuBW(priv->cgroup);
 
@@ -9318,6 +9373,7 @@ cleanup:
     if (vm)
         virObjectUnlock(vm);
     virObjectUnref(caps);
+    virObjectUnref(cfg);
     return ret;
 }
 
@@ -15523,11 +15579,17 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
     if (virDomainSetBlockIoTuneEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Block I/O tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;
 
     priv = vm->privateData;
-    cfg = virQEMUDriverGetConfig(driver);
 
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto endjob;
@@ -15670,6 +15732,7 @@ qemuDomainGetBlockIoTune(virDomainPtr dom,
     int ret = -1;
     size_t i;
     virCapsPtr caps = NULL;
+    virQEMUDriverConfigPtr cfg = NULL;
 
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG |
@@ -15684,6 +15747,13 @@ qemuDomainGetBlockIoTune(virDomainPtr dom,
     if (virDomainGetBlockIoTuneEnsureACL(dom->conn, vm->def) < 0)
         goto cleanup;
 
+    cfg = virQEMUDriverGetConfig(driver);
+    if (!cfg->privileged) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Block I/O tuning is not available in session mode"));
+        goto cleanup;
+    }
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
@@ -15786,6 +15856,7 @@ cleanup:
     if (vm)
         virObjectUnlock(vm);
     virObjectUnref(caps);
+    virObjectUnref(cfg);
     return ret;
 }