virsh maxvcpus throws "error: invalid argument: unable to find any emulator to serve 'ppc64le' architecture"

== Comment: #0 - Satheesh Rajendran <email address hidden> - 2017-03-20 05:00:21 ==
---Problem Description---
virsh maxvcpus throws "error: invalid argument: unable to find any emulator to serve 'ppc64le' architecture"

Contact Information = <email address hidden>

---uname output---
Linux ltc-test-ci1 4.10.0-13-generic #15-Ubuntu SMP Thu Mar 9 20:27:28 UTC 2017 ppc64le ppc64le ppc64le GNU/Linux

Machine Type = power 8 ppc64le

---Debugger---
A debugger is not configured

---Steps to Reproduce---
 #virsh maxvcpus
error: invalid argument: unable to find any emulator to serve 'ppc64le' architecture

Userspace tool common name: libvirt

The userspace tool has the following bit modes: both

Userspace rpm: ii libvirt-bin 2.5.0-3ubuntu4 ppc64el programs for the libvirt library,ii qemu-kvm 1:2.8+dfsg-3ubuntu2 ppc64el QEMU Full virtualization

Userspace tool obtained from project website: na

*Additional Instructions for <email address hidden>:
-Post a private note with access information to the machine that the bug is occuring on.
-Attach ltrace and strace of userspace application.

== Comment: #1 - Satheesh Rajendran <email address hidden> - 2017-03-20 05:07:45 ==
#virsh capabilities
<capabilities>

  <host>
    <uuid>08424246-091a-43b7-9eff-c78858b179ce</uuid>
    <cpu>
      <arch>ppc64le</arch>
      <model>POWER8</model>
      <vendor>IBM</vendor>
      <topology sockets='1' cores='5' threads='8'/>
      <pages unit='KiB' size='64'/>
      <pages unit='KiB' size='16384'/>
      <pages unit='KiB' size='16777216'/>
    </cpu>
...
...
...
....
<guest>
    <os_type>hvm</os_type>
    <arch name='ppc64le'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-ppc64le</emulator>
      <machine maxCpus='255'>pseries-zesty</machine>
      <machine canonical='pseries-zesty' maxCpus='255'>pseries</machine>
      <machine maxCpus='1'>ref405ep</machine>
      <machine maxCpus='1'>virtex-ml507</machine>
      <machine maxCpus='2048'>powernv</machine>
      <machine maxCpus='32'>ppce500</machine>
      <machine maxCpus='15'>mpc8544ds</machine>
      <machine maxCpus='1'>bamboo</machine>
      <machine maxCpus='1'>g3beige</machine>
      <machine maxCpus='1'>prep</machine>
      <machine maxCpus='1'>mac99</machine>
      <machine maxCpus='255'>pseries-2.6</machine>
      <machine maxCpus='255'>pseries-2.7</machine>
      <machine maxCpus='255'>pseries-2.8</machine>
      <machine maxCpus='255'>pseries-2.4</machine>
      <machine maxCpus='255'>pseries-2.5</machine>
      <machine maxCpus='255'>pseries-2.2</machine>
      <machine maxCpus='1'>taihu</machine>
      <machine maxCpus='255'>pseries-2.3</machine>
      <machine maxCpus='255'>pseries-xenial</machine>
      <machine maxCpus='255'>pseries-yakkety</machine>
      <machine maxCpus='255'>pseries-2.1</machine>
      <domain type='qemu'/>
      <domain type='kvm'>
        <emulator>/usr/bin/kvm</emulator>
        <machine maxCpus='255'>pseries-zesty</machine>
        <machine canonical='pseries-zesty' maxCpus='255'>pseries</machine>
        <machine maxCpus='1'>ref405ep</machine>
        <machine maxCpus='1'>virtex-ml507</machine>
        <machine maxCpus='2048'>powernv</machine>
        <machine maxCpus='32'>ppce500</machine>
        <machine maxCpus='15'>mpc8544ds</machine>
        <machine maxCpus='1'>bamboo</machine>
        <machine maxCpus='1'>g3beige</machine>
        <machine maxCpus='1'>prep</machine>
        <machine maxCpus='1'>mac99</machine>
        <machine maxCpus='255'>pseries-2.6</machine>
        <machine maxCpus='255'>pseries-2.7</machine>
        <machine maxCpus='255'>pseries-2.8</machine>
        <machine maxCpus='255'>pseries-2.4</machine>
        <machine maxCpus='255'>pseries-2.5</machine>
        <machine maxCpus='255'>pseries-2.2</machine>
        <machine maxCpus='1'>taihu</machine>
        <machine maxCpus='255'>pseries-2.3</machine>
        <machine maxCpus='255'>pseries-xenial</machine>
        <machine maxCpus='255'>pseries-yakkety</machine>
        <machine maxCpus='255'>pseries-2.1</machine>
      </domain>
    </arch>
    <features>
      <cpuselection/>
      <deviceboot/>
      <disksnapshot default='on' toggle='no'/>
    </features>
  </guest>
...
...

~# arch
ppc64le

== Comment: #2 - VIPIN K. PARASHAR <email address hidden> - 2017-03-20 06:40:12 ==
$ git log bd4ae4f5e881276b -1
commit bd4ae4f5e881276b05e48fbd55a29c57cf1a25ff
Author: Peter Krempa <email address hidden>
Date: Thu Dec 8 09:36:43 2016 +0100

    virsh: maxvcpus: Always fall back to the old command if domain caps fail

    1ec22be5 added code that detects the maximum cpu count according to
    domain capabilities. The code fell back to the old command only if the
    API was not supported. If the API fails for other reasons the command
    would fail. There's no point in not trying the old API in such case.

    https://bugzilla.redhat.com/show_bug.cgi?id=1402690

$ git tag --contains bd4ae4f5e881276b0 | grep -v rc
v3.0.0
v3.1.0
$

Commit bd4ae4f5e881276b should fix this issue.
Its available in libvirt version 3.0 and above.