Merge "libvirt: Allow discrete online pCPUs for pinning"

nova/tests/unit/virt/libvirt/test_driver.py

@@ -4327,6 +4327,48 @@ def test_get_all_block_devices(self, mock_list):
         self.assertEqual(devices, ['/path/to/dev/1', '/path/to/dev/3'])
         mock_list.assert_called_with()
 
+    @mock.patch('nova.virt.libvirt.host.Host.get_online_cpus')
+    def test_get_host_vcpus(self, get_online_cpus):
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.flags(vcpu_pin_set="4-5")
+        get_online_cpus.return_value = set([4, 5, 6])
+        expected_vcpus = 2
+        vcpus = drvr._get_vcpu_total()
+        self.assertEqual(expected_vcpus, vcpus)
+
+    @mock.patch('nova.virt.libvirt.host.Host.get_online_cpus')
+    def test_get_host_vcpus_out_of_range(self, get_online_cpus):
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        self.flags(vcpu_pin_set="4-6")
+        get_online_cpus.return_value = set([4, 5])
+        self.assertRaises(exception.Invalid, drvr._get_vcpu_total)
+
+    @mock.patch('nova.virt.libvirt.host.Host.get_online_cpus')
+    def test_get_host_vcpus_libvirt_error(self, get_online_cpus):
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        not_supported_exc = fakelibvirt.make_libvirtError(
+            fakelibvirt.libvirtError,
+            'this function is not supported by the connection driver:'
+            ' virNodeNumOfDevices',
+            error_code=fakelibvirt.VIR_ERR_NO_SUPPORT)
+        self.flags(vcpu_pin_set="4-6")
+        get_online_cpus.side_effect = not_supported_exc
+        self.assertRaises(exception.Invalid, drvr._get_vcpu_total)
+
+    @mock.patch('nova.virt.libvirt.host.Host.get_online_cpus')
+    def test_get_host_vcpus_libvirt_error_success(self, get_online_cpus):
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        not_supported_exc = fakelibvirt.make_libvirtError(
+            fakelibvirt.libvirtError,
+            'this function is not supported by the connection driver:'
+            ' virNodeNumOfDevices',
+            error_code=fakelibvirt.VIR_ERR_NO_SUPPORT)
+        self.flags(vcpu_pin_set="1")
+        get_online_cpus.side_effect = not_supported_exc
+        expected_vcpus = 1
+        vcpus = drvr._get_vcpu_total()
+        self.assertEqual(expected_vcpus, vcpus)
+
     @mock.patch.object(host.Host, "has_min_version", return_value=True)
     def test_quiesce(self, mock_has_min_version):
         self.create_fake_libvirt_mock(lookupByName=self.fake_lookup)

nova/virt/libvirt/driver.py

@@ -4476,7 +4476,25 @@ def _get_vcpu_total(self):
             return self._vcpu_total
 
         available_ids = hardware.get_vcpu_pin_set()
-        if sorted(available_ids)[-1] >= total_pcpus:
+        # We get the list of online CPUs on the host and see if the requested
+        # set falls under these. If not, we retain the old behavior.
+        online_pcpus = None
+        try:
+            online_pcpus = self._host.get_online_cpus()
+        except libvirt.libvirtError as ex:
+            error_code = ex.get_error_code()
+            LOG.warn(_LW("Couldn't retrieve the online CPUs due to a Libvirt "
+                         "error: %(error)s with error code: %(error_code)s"),
+                     {'error': ex, 'error_code': error_code})
+        if online_pcpus:
+            if not (available_ids <= online_pcpus):
+                msg = (_("Invalid vcpu_pin_set config, one or more of the "
+                         "specified cpuset is not online. Online cpuset(s): "
+                         "%(online)s, requested cpuset(s): %(req)s"),
+                       {'online': sorted(online_pcpus),
+                        'req': sorted(available_ids)})
+                raise exception.Invalid(msg)
+        elif sorted(available_ids)[-1] >= total_pcpus:
             raise exception.Invalid(_("Invalid vcpu_pin_set config, "
                                       "out of hypervisor cpu range."))
         self._vcpu_total = len(available_ids)