There is the case where cpu affinites for vcpu of qemu doesn't work correctly. For example, if only one vcpupin setting entry is provided and its setting is not for vcpu0, it doesn't work. # virsh dumpxml VM ... <vcpu>4</vcpu> <cputune> <vcpupin vcpu='3' cpuset='9-11'/> </cputune> ... # virsh start VM Domain VM started # virsh vcpuinfo VM VCPU: 0 CPU: 31 State: running CPU time: 2.5s CPU Affinity: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy VCPU: 1 CPU: 12 State: running CPU time: 0.9s CPU Affinity: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy VCPU: 2 CPU: 30 State: running CPU time: 1.5s CPU Affinity: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy VCPU: 3 CPU: 13 State: running CPU time: 1.7s CPU Affinity: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy This patch fixes this problem. Signed-off-by: Taku Izumi <izumi.taku(a)jp.fujitsu.com&gt; --- src/qemu/qemu_process.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) Index: libvirt/src/qemu/qemu_process.c =================================================================== --- libvirt.orig/src/qemu/qemu_process.c +++ libvirt/src/qemu/qemu_process.c @@ -1194,7 +1194,7 @@ qemuProcessSetVcpuAffinites(virConnectPt virNodeInfo nodeinfo; pid_t vcpupid; unsigned char *cpumask; - int vcpu, cpumaplen, hostcpus, maxcpu; + int vcpu, cpumaplen, hostcpus, maxcpu, n; unsigned char *cpumap = NULL; int ret = -1; @@ -1223,14 +1223,12 @@ qemuProcessSetVcpuAffinites(virConnectPt return -1; } - for (vcpu = 0; vcpu < def->cputune.nvcpupin; vcpu++) { - if (vcpu != def->cputune.vcpupin[vcpu]->vcpuid) - continue; - + for (n = 0; n < def->cputune.nvcpupin; n++) { int i; + vcpu = def->cputune.vcpupin[n]->vcpuid; memset(cpumap, 0, cpumaplen); - cpumask = (unsigned char *)def->cputune.vcpupin[vcpu]->cpumask; + cpumask = (unsigned char *)def->cputune.vcpupin[n]->cpumask; vcpupid = priv->vcpupids[vcpu]; /* Convert cpumask to bitmap here. */