[libvirt] [PATCH] qemu_driver: fix setting vcpus for offline domain

[Pavel Hrdina]

Commit e3435caf fixed hot-plugging of vcpus with strict memory pinning
on NUMA hosts, but unfortunately it also broke updating number of vcpus
for offline guests using our API.

The issue is that we try to create a cpu cgroup for non-running guest
which fails as there are no cgroups for that domain. We should create
cgroups and update cpuset.mems only if we are hot-plugging.

Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
---
 src/qemu/qemu_driver.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index cdf4173..3a343d0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -4576,21 +4576,23 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
 
     priv = vm->privateData;
 
-    if (virCgroupNewEmulator(priv->cgroup, false, &cgroup_temp) < 0)
-        goto cleanup;
-
-    if (!(all_nodes = virNumaGetHostNodeset()))
-        goto cleanup;
-
-    if (!(all_nodes_str = virBitmapFormat(all_nodes)))
-        goto cleanup;
-
     if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;
 
-    if (virCgroupGetCpusetMems(cgroup_temp, &mem_mask) < 0 ||
-        virCgroupSetCpusetMems(cgroup_temp, all_nodes_str) < 0)
-        goto endjob;
+    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
+        if (virCgroupNewEmulator(priv->cgroup, false, &cgroup_temp) < 0)
+            goto cleanup;
+
+        if (!(all_nodes = virNumaGetHostNodeset()))
+            goto cleanup;
+
+        if (!(all_nodes_str = virBitmapFormat(all_nodes)))
+            goto cleanup;
+
+        if (virCgroupGetCpusetMems(cgroup_temp, &mem_mask) < 0 ||
+            virCgroupSetCpusetMems(cgroup_temp, all_nodes_str) < 0)
+            goto endjob;
+    }
 
     maximum = (flags & VIR_DOMAIN_VCPU_MAXIMUM) != 0;
     flags &= ~VIR_DOMAIN_VCPU_MAXIMUM;
-- 
2.0.5