[PATCH 4/5] KVM test: setup tap fd and pass it to qemu-kvm v3

[Lucas Meneghel Rodrigues <lmr@redhat.com>]

We used to use qemu-ifup to manage the tap which have several
limitations:

1) If we want to specify a bridge, we must create a customized
qemu-ifup file as the default script always match the first bridge.
2) It's hard to add support for macvtap device.

So this patch let kvm subtest control the tap creation and setup then
pass it to qemu-kvm. User could specify the bridge he want to used in
configuration file.

The original autoconfiguration was changed by private bridge setup.

Changes from v1:
* Combine the private bridge config and TAP fd in one patchset,
dropped the "auto" mode
* Close TAP fds on VM.destroy() (thanks to Amos Kong for finding
the problem)

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
---
 client/tests/kvm/scripts/qemu-ifup |   11 -------
 client/virt/kvm_vm.py              |   59 +++++++++++++++++++++++------------
 client/virt/virt_utils.py          |    8 ++++-
 3 files changed, 45 insertions(+), 33 deletions(-)
 delete mode 100755 client/tests/kvm/scripts/qemu-ifup

diff --git a/client/tests/kvm/scripts/qemu-ifup b/client/tests/kvm/scripts/qemu-ifup
deleted file mode 100755
index c4debf5..0000000
--- a/client/tests/kvm/scripts/qemu-ifup
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/bin/sh
-
-# The following expression selects the first bridge listed by 'brctl show'.
-# Modify it to suit your needs.
-switch=$(/usr/sbin/brctl show | awk 'NR==2 { print $1 }')
-
-/bin/echo 1 > /proc/sys/net/ipv6/conf/${switch}/disable_ipv6
-/sbin/ifconfig $1 0.0.0.0 up
-/usr/sbin/brctl addif ${switch} $1
-/usr/sbin/brctl setfd ${switch} 0
-/usr/sbin/brctl stp ${switch} off
diff --git a/client/virt/kvm_vm.py b/client/virt/kvm_vm.py
index c9bb273..9b26dee 100644
--- a/client/virt/kvm_vm.py
+++ b/client/virt/kvm_vm.py
@@ -7,7 +7,7 @@ Utility classes and functions to handle Virtual Machine creation using qemu.
 import time, os, logging, fcntl, re, commands, glob
 from autotest_lib.client.common_lib import error
 from autotest_lib.client.bin import utils
-import virt_utils, virt_vm, kvm_monitor, aexpect
+import virt_utils, virt_vm, virt_test_setup, kvm_monitor, aexpect
 
 
 class VM(virt_vm.BaseVM):
@@ -41,6 +41,7 @@ class VM(virt_vm.BaseVM):
             self.pci_assignable = None
             self.netdev_id = []
             self.device_id = []
+            self.tapfds = []
             self.uuid = None
 
 
@@ -240,19 +241,17 @@ class VM(virt_vm.BaseVM):
                 cmd += ",id='%s'" % device_id
             return cmd
 
-        def add_net(help, vlan, mode, ifname=None, script=None,
-                    downscript=None, tftp=None, bootfile=None, hostfwd=[],
-                    netdev_id=None, netdev_extra_params=None):
+        def add_net(help, vlan, mode, ifname=None, tftp=None, bootfile=None,
+                    hostfwd=[], netdev_id=None, netdev_extra_params=None,
+                    tapfd=None):
             if has_option(help, "netdev"):
                 cmd = " -netdev %s,id=%s" % (mode, netdev_id)
                 if netdev_extra_params:
                     cmd += ",%s" % netdev_extra_params
             else:
                 cmd = " -net %s,vlan=%d" % (mode, vlan)
-            if mode == "tap":
-                if ifname: cmd += ",ifname='%s'" % ifname
-                if script: cmd += ",script='%s'" % script
-                cmd += ",downscript='%s'" % (downscript or "no")
+            if mode == "tap" and tapfd:
+                cmd += ",fd=%d" % tapfd
             elif mode == "user":
                 if tftp and "[,tftp=" in help:
                     cmd += ",tftp='%s'" % tftp
@@ -422,20 +421,22 @@ class VM(virt_vm.BaseVM):
             qemu_cmd += add_nic(help, vlan, nic_params.get("nic_model"), mac,
                                 device_id, netdev_id, nic_params.get("nic_extra_params"))
             # Handle the '-net tap' or '-net user' or '-netdev' part
-            script = nic_params.get("nic_script")
-            downscript = nic_params.get("nic_downscript")
             tftp = nic_params.get("tftp")
-            if script:
-                script = virt_utils.get_path(root_dir, script)
-            if downscript:
-                downscript = virt_utils.get_path(root_dir, downscript)
             if tftp:
                 tftp = virt_utils.get_path(root_dir, tftp)
-            qemu_cmd += add_net(help, vlan, nic_params.get("nic_mode", "user"),
-                                vm.get_ifname(vlan),
-                                script, downscript, tftp,
+            if nic_params.get("nic_mode") == "tap":
+                try:
+                    tapfd = vm.tapfds[vlan]
+                except:
+                    tapfd = None
+            else:
+                tapfd = None
+            qemu_cmd += add_net(help, vlan,
+                                nic_params.get("nic_mode", "user"),
+                                vm.get_ifname(vlan), tftp,
                                 nic_params.get("bootp"), redirs, netdev_id,
-                                nic_params.get("netdev_extra_params"))
+                                nic_params.get("netdev_extra_params"),
+                                tapfd)
             # Proceed to next NIC
             vlan += 1
 
@@ -558,6 +559,10 @@ class VM(virt_vm.BaseVM):
         @raise VMBadPATypeError: If an unsupported PCI assignment type is
                 requested
         @raise VMPAError: If no PCI assignable devices could be assigned
+        @raise TAPCreationError: If fail to create tap fd
+        @raise BRAddIfError: If fail to add a tap to a bridge
+        @raise TAPBringUpError: If fail to bring up a tap
+        @raise PrivateBridgeError: If fail to bring the private bridge
         """
         error.context("creating '%s'" % self.name)
         self.destroy(free_mac_addresses=False)
@@ -621,12 +626,24 @@ class VM(virt_vm.BaseVM):
                 guest_port = int(redir_params.get("guest_port"))
                 self.redirs[guest_port] = host_ports[i]
 
-            # Generate netdev/device IDs for all NICs
+            # Generate netdev IDs for all NICs and create TAP fd
             self.netdev_id = []
-            self.device_id = []
+            self.tapfds = []
+            vlan = 0
             for nic in params.objects("nics"):
                 self.netdev_id.append(virt_utils.generate_random_id())
                 self.device_id.append(virt_utils.generate_random_id())
+                nic_params = params.object_params(nic)
+                if nic_params.get("nic_mode") == "tap":
+                    ifname = self.get_ifname(vlan)
+                    brname = nic_params.get("bridge")
+                    if brname == "private":
+                        brname = virt_test_setup.PrivateBridgeConfig().brname
+                    tapfd = virt_utils.open_tap("/dev/net/tun", ifname)
+                    virt_utils.add_to_bridge(ifname, brname)
+                    virt_utils.bring_up_ifname(ifname)
+                    self.tapfds.append(tapfd)
+                vlan += 1
 
             # Find available VNC port, if needed
             if params.get("display") == "vnc":
@@ -865,6 +882,8 @@ class VM(virt_vm.BaseVM):
                 num_nics = len(self.params.objects("nics"))
                 for vlan in range(num_nics):
                     self.free_mac_address(vlan)
+            for tapfd in self.tapfds:
+                os.close(tapfd)
 
 
     @property
diff --git a/client/virt/virt_utils.py b/client/virt/virt_utils.py
index 7eeaf4f..101427e 100644
--- a/client/virt/virt_utils.py
+++ b/client/virt/virt_utils.py
@@ -56,12 +56,16 @@ class NetError(Exception):
 
 
 class TAPModuleError(NetError):
-    def __init__(self, devname):
+    def __init__(self, devname, action="open", details=None):
         NetError.__init__(self, devname)
         self.devname = devname
 
     def __str__(self):
-        return "Can't open %s" % self.devname
+        e_msg = "Can't %s %s" % (self.action, self.devname)
+        if self.details is not None:
+            e_msg += " : %s" % details
+        return e_msg
+
 
 class TAPNotExistError(NetError):
     def __init__(self, ifname):
-- 
1.7.5.1