I submitted bug https://bugzilla.redhat.com/show_bug.cgi?id=1038363 for being unable to raise the persistent mem/vcpu values above a live domain’s maxmem/maxvcpu values (rather than the persistent maxmem/maxvcpu values). I was asked to submit my patch here for a wider review.

For memory, check the newmem value against mem.max_baloon of the live def for non-persistent changes, or mem.max_baloon of the persistent def for persistent changes. Same theory for setting vcpus/maxvcpus.

--- a/libvirt0/libvirt-1.1.1/src/qemu/qemu_driver.c

+++ b/libvirt0/libvirt-1.1.1/src/qemu/qemu_driver.c

@@ -2236,13 +2236,13 @@ static int qemuDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,

     } else {

         /* resize the current memory */

 

-        if (newmem > vm->def->mem.max_balloon) {

-            virReportError(VIR_ERR_INVALID_ARG, "%s",

-                           _("cannot set memory higher than max memory"));

-            goto endjob;

-        }

-

         if (flags & VIR_DOMAIN_AFFECT_LIVE) {

+            if (newmem > vm->def->mem.max_balloon) {

+                virReportError(VIR_ERR_INVALID_ARG, "%s",

+                    _("cannot set memory higher than max memory"));

+                goto endjob;

+            }

+

             priv = vm->privateData;

             qemuDomainObjEnterMonitor(driver, vm);

             r = qemuMonitorSetBalloon(priv->mon, newmem);

@@ -2262,6 +2262,12 @@ static int qemuDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,

         }

 

         if (flags & VIR_DOMAIN_AFFECT_CONFIG) {

+            if (newmem > persistentDef->mem.max_balloon) {

+                virReportError(VIR_ERR_INVALID_ARG, "%s",

+                    _("cannot set memory higher than max memory"));

+                goto endjob;

+            }

+

             sa_assert(persistentDef);

             persistentDef->mem.cur_balloon = newmem;

             ret = virDomainSaveConfig(cfg->configDir, persistentDef);

@@ -4160,6 +4166,7 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,

     virDomainDefPtr persistentDef;

     int ret = -1;

     bool maximum;

+    unsigned int maxvcpus;

     virQEMUDriverConfigPtr cfg = NULL;

     virCapsPtr caps = NULL;

     qemuAgentCPUInfoPtr cpuinfo = NULL;

@@ -4207,11 +4214,12 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,

         goto endjob;

     }

 

-    if (!maximum && nvcpus > vm->def->maxvcpus) {

+    maxvcpus = (flags & VIR_DOMAIN_AFFECT_LIVE) ? vm->def->maxvcpus : persistentDef->maxvcpus;

+    if (!maximum && nvcpus > maxvcpus) {

         virReportError(VIR_ERR_INVALID_ARG,

                        _("requested vcpus is greater than max allowable"

                          " vcpus for the domain: %d > %d"),

-                       nvcpus, vm->def->maxvcpus);

+                       nvcpus, maxvcpus);

         goto endjob;

     }