Description of problem:

/sys/fs/cgroup/cpuset/machine.slice/cpuset.cpus on machine.slice creation is always set to cores that emulator is pinned to via <emulatorpin>. This results in following error on VM startup: Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2d2\x2dwin.scope/vcpu0/cpuset.cpus': Permission denied


Compiled against library: libvirt 2.3.0
Using library: libvirt 2.3.0
Using API: QEMU 2.3.0
Running hypervisor: QEMU 2.7.0


Always reproducible.


Steps to Reproduce:
1. Create VM with cpu setup:
  <vcpu placement='static'>4</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='2'/>
    <vcpupin vcpu='1' cpuset='3'/>
    <vcpupin vcpu='2' cpuset='4'/>
    <vcpupin vcpu='3' cpuset='5'/>
    <emulatorpin cpuset='0-1'/>
  </cputune>
  <cpu mode='host-passthrough'>
    <topology sockets='1' cores='4' threads='1'/>
  </cpu>
2. Start VM via virsh or virt-manager.

Actual results:
Error: Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2d2\x2dwin.scope/vcpu0/cpuset.cpus': Permission denied
~ % cat /sys/fs/cgroup/cpuset/machine.slice/cpuset.cpus
0-1

Expected results:
No error, VM should start.
~ % cat /sys/fs/cgroup/cpuset/machine.slice/cpuset.cpus
0-5

Additional info:
As a workaround i added following line to /etc/libvirt/hooks/qemu script:
echo 0-5 > /sys/fs/cgroup/cpuset/machine.slice/cpuset.cpus

With this workaround VM always fails starting the first time but starts properly the second time.