From b67614fe878ea3b6bb6240f9989a21c2c3c0b2df Mon Sep 17 00:00:00 2001
From: lyanchih <lyan.h@inwinstack.com>
Date: Thu, 30 Jul 2015 09:16:16 +0000
Subject: [PATCH] libvirt: serial console ports count upper limit needs to be
 checked

There is a limit of 4 serial ports on qemu_x86. If number of serial port
over limit, qemu will throw error message with
"libvirtError: internal error:
process exited while connecting to monitor: qemu-system-x86_64: -device
isa-serial,chardev=charserial4, id=serial4: Max. supported number of ISA
serial ports is 4."

We should check upper limit of serial console port.

Change-Id: Id14c94dd658868037eeab1524a9984354cdb4071
Closes-Bug: 1478607
---
 nova/exception.py                           |  5 ++++
 nova/tests/unit/virt/libvirt/test_driver.py | 29 +++++++++++++++++++++
 nova/virt/libvirt/driver.py                 | 25 +++++++++++++++---
 3 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/nova/exception.py b/nova/exception.py
index 6ad203b3f338..8295e1cbaa11 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -1958,6 +1958,11 @@ class ImageSerialPortNumberExceedFlavorValue(Invalid):
                 "ports passed in image meta.")
 
 
+class SerialPortNumberLimitExceeded(Invalid):
+    msg_fmt = _("Maximum number of serial port exceeds %(allowed)d "
+                "for %(virt_type)s")
+
+
 class InvalidImageConfigDrive(Invalid):
     msg_fmt = _("Image's config drive option '%(config_drive)s' is invalid")
 
diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index ae4504ce121a..e502360b447c 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -3318,6 +3318,35 @@ class LibvirtConnTestCase(test.NoDBTestCase):
             self.assertIsInstance(console_device, device_type)
             self.assertEqual("tcp", console_device.type)
 
+    @mock.patch('nova.virt.hardware.get_number_of_serial_ports',
+                return_value=4)
+    @mock.patch.object(libvirt_driver.libvirt_utils, 'get_arch',
+                       side_effect=[arch.X86_64, arch.S390, arch.S390X])
+    def test_create_serial_console_devices_with_limit_exceeded_based_on_arch(
+            self, mock_get_arch, mock_get_port_number):
+        self.flags(enabled=True, group='serial_console')
+        self.flags(virt_type="qemu", group='libvirt')
+        flavor = 'fake_flavor'
+        image_meta = objects.ImageMeta()
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
+        guest = vconfig.LibvirtConfigGuest()
+        self.assertRaises(exception.SerialPortNumberLimitExceeded,
+                          drvr._create_serial_console_devices,
+                          guest, None, flavor, image_meta)
+        mock_get_arch.assert_called_with(image_meta)
+        mock_get_port_number.assert_called_with(flavor,
+                                                image_meta)
+
+        drvr._create_serial_console_devices(guest, None, flavor, image_meta)
+        mock_get_arch.assert_called_with(image_meta)
+        mock_get_port_number.assert_called_with(flavor,
+                                                image_meta)
+
+        drvr._create_serial_console_devices(guest, None, flavor, image_meta)
+        mock_get_arch.assert_called_with(image_meta)
+        mock_get_port_number.assert_called_with(flavor,
+                                                image_meta)
+
     @mock.patch('nova.console.serial.acquire_port')
     def test_get_guest_config_serial_console(self, acquire_port):
         self.flags(enabled=True, group='serial_console')
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index a8bafe8ae12f..82b2c225b601 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -491,6 +491,12 @@ MIN_QEMU_PPC64_VERSION = (2, 1, 0)
 # Names of the types that do not get compressed during migration
 NO_COMPRESSION_TYPES = ('qcow2',)
 
+
+# number of serial console limit
+QEMU_MAX_SERIAL_PORTS = 4
+# Qemu supports 4 serial consoles, we remove 1 because of the PTY one defined
+ALLOWED_QEMU_SERIAL_PORTS = QEMU_MAX_SERIAL_PORTS - 1
+
 # realtime suppport
 MIN_LIBVIRT_REALTIME_VERSION = (1, 2, 13)
 
@@ -4182,6 +4188,13 @@ class LibvirtDriver(driver.ComputeDriver):
                 hv.vapic = True
             guest.features.append(hv)
 
+    def _check_number_of_serial_console(self, num_ports):
+        virt_type = CONF.libvirt.virt_type
+        if (virt_type in ("kvm", "qemu") and
+            num_ports > ALLOWED_QEMU_SERIAL_PORTS):
+            raise exception.SerialPortNumberLimitExceeded(
+                allowed=ALLOWED_QEMU_SERIAL_PORTS, virt_type=virt_type)
+
     def _create_serial_console_devices(self, guest, instance, flavor,
                                        image_meta):
         guest_arch = libvirt_utils.get_arch(image_meta)
@@ -4189,11 +4202,15 @@ class LibvirtDriver(driver.ComputeDriver):
         if CONF.serial_console.enabled:
             num_ports = hardware.get_number_of_serial_ports(
                 flavor, image_meta)
+
+            if guest_arch in (arch.S390, arch.S390X):
+                console_cls = vconfig.LibvirtConfigGuestConsole
+            else:
+                console_cls = vconfig.LibvirtConfigGuestSerial
+                self._check_number_of_serial_console(num_ports)
+
             for port in six.moves.range(num_ports):
-                if guest_arch in (arch.S390, arch.S390X):
-                    console = vconfig.LibvirtConfigGuestConsole()
-                else:
-                    console = vconfig.LibvirtConfigGuestSerial()
+                console = console_cls()
                 console.port = port
                 console.type = "tcp"
                 console.listen_host = (