Changes from v1 to v2:
- changed function name prefixes to 'iface' from previous 'Iface'

- Further to make make syntax-check pass:
 - indentation fix in interface.h
 - added entry to POTFILES.in

I am consolidating network interface related functions used in nwfilter
and macvtap code in utils/interface.c. All function names are prefixed
with 'Iface'. The following functions are now available through
interface.h:

int ifaceCtrl(const char *name, bool up);
int ifaceUp(const char *name);
int ifaceDown(const char *name);

int ifaceCheck(bool reportError, const char *ifname,
               const unsigned char *macaddr, int ifindex);

int ifaceGetIndex(bool reportError, const char *ifname, int *ifindex);

I added 'int ifindex' as parameter to ifaceCheck to the original
function and modified the code accordingly.

This patch implements support for learning a VM's IP address. It uses
the pcap library to listen on the VM's backend network interface (tap)
or the physical ethernet device (macvtap) and tries to capture packets
with source or destination MAC address of the VM and learn from DHCP
Offers, ARP traffic, or first-sent IPv4 packet what the IP address of
the VM's interface is. This then allows to instantiate the network
traffic filtering rules without the user having to provide the IP
parameter somewhere in the filter description or in the interface
description as a parameter. This only supports to detect the parameter
IP, which is for the assumed single IPv4 address of a VM. There is not
support for interfaces that may have multiple  IP addresses (IP
aliasing) or IPv6 that may then require more than one valid IP address
to be detected. A VM can have multiple independent interfaces that each
uses a different IP address and in that case it will be attempted to
detect each one of the address independently.

So, when for example an interface description in the domain XML has
looked like this up to now:

    <interface type='bridge'>
      <source bridge='mybridge'/>
      <model type='virtio'/>
      <filterref filter='clean-traffic'>
        <parameter name='IP' value='10.2.3.4'/>
      </filterref>
    </interface>

you may omit the IP parameter:

    <interface type='bridge'>
      <source bridge='mybridge'/>
      <model type='virtio'/>
      <filterref filter='clean-traffic'/>
    </interface>

Internally I am walking the 'tree' of a VM's referenced network filters
and determine with the given variables which variables are missing. Now,
the above IP parameter may be missing and this causes a libvirt-internal
thread to be started that uses the pcap library's API to listen to the
backend interface  (in case of macvtap to the physical interface) in an
attempt to determine the missing IP parameter. If the backend interface
disappears the thread terminates assuming the VM was brought down. In
case of a macvtap device a timeout is being used to wait for packets
from the given VM (filtering by VM's interface MAC address). If the VM's
macvtap device disappeared the thread also terminates. In all other
cases it tries to determine the IP address of the VM and will then apply
the rules late on the given interface, which would have happened
immediately if the IP parameter had been explicitly given. In case an
error happens while the firewall rules are applied, the VM's backend
interface is 'down'ed preventing it to communicate. Reasons for failure
for applying the network firewall rules may that an ebtables/iptables
command failes or OOM errors. Essentially the same failure reasons may
occur as when the firewall rules are applied immediately on VM start,
except that due to the late application of the filtering rules the VM
now is already running and cannot be hindered anymore from starting.
Bringing down the whole VM would probably be considered too drastic.
While a VM's IP address is attempted to be determined only limited
updates to network filters are allowed. In particular it is prevented
that filters are modified in such a way that they would introduce new
variables.

A caveat: The algorithm does not know which one is the appropriate IP
address of a VM. If the VM spoofs an IP address in its first ARP traffic
or IPv4 packets its filtering rules will be instantiated for this IP
address, thus 'locking' it to the found IP address. So, it's still
'safer' to explicitly provide the IP address of a VM's interface in the
filter description if it is known beforehand.

* configure.ac: detect libpcap
* libvirt.spec.in: require libpcap[-devel] if qemu is built
* src/internal.h: add the new ATTRIBUTE_PACKED define
* src/Makefile.am src/libvirt_private.syms: add the new modules and symbols
* src/nwfilter/nwfilter_learnipaddr.[ch]: new module being added
* src/nwfilter/nwfilter_driver.c src/conf/nwfilter_conf.[ch]
  src/nwfilter/nwfilter_ebiptables_driver.[ch]
  src/nwfilter/nwfilter_gentech_driver.[ch]: plu the new functionality in
* tests/nwfilterxml2xmltest: extend testing

Signed-off-by: NChris Lalancette <clalance@redhat.com>

Signed-off-by: NChris Lalancette <clalance@redhat.com>

The clock timer XML is being updated in the following ways (based on
further off-list discussion that was missed during the initial
implementation):

1) 'wallclock' is changed to 'track', and the possible values are 'boot'
 (corresponds to old 'host'), 'guest', and 'wall'.

2) 'mode' has an additional value 'smpsafe'

3) when tickpolicy='catchup', there can be an optional sub-element of
   timer called 'catchup':

   <catchup threshold=123 slew=120 limit=10000/>

Those three values are all longs, always optional, and if they are present,
they are positive. Internally, 0 indicates "unspecified".

* docs/schemas/domain.rng: updated RNG definition to account for changes

* src/conf/domain_conf.h: change the C struct and enums to match changes.

* src/conf/domain_conf.c: timer parse and format functions changed to
                          handle the new selections and new element.

* src/libvirt_private.syms: *TimerWallclock* changes to *TimerTrack*

* src/qemu/qemu_conf.c: again, account for Wallclock --> Track change.

virParseVersionString uses virStrToLong_ui instead of sscanf.

This also fixes a bug in the UML driver, that always returned 0
as version number.

Introduce STRSKIP to check if a string has a certain prefix and
to skip this prefix.

This extension is described in

http://www.redhat.com/archives/libvir-list/2010-March/msg00304.html

Currently all attributes are optional, except name.

* src/conf/domain_conf.h: add data definition for virDomainTimerDef
  and add a list of them to virDomainClockDef
* src/conf/domain_conf.c: XML parser and formatter for a timer inside a clock
* src/libvirt_private.syms: add new Timer enum helper functions to symbols

This exports 3 basic routines:
  - virHookInitialize() initializing the hook support by looking for
    scripts availability
  - virHookPresent() used to test if there is a hook for a given driver
  - virHookCall() which actually calls a synchronous script hook with
    the needed parameters
Note that this doesn't expose any public API except for the locations
and arguments passed to the scripts

* src/Makefile.am: add the 2 new files
* src/util/hooks.h src/util/hooks.c: implements the 3 functions
* src/libvirt_private.syms: export the 3 symbols internally
* po/POTFILES.in: add src/util/hooks.c to translatables modules

used to read the data from virExec stdout/err file descriptors

* src/util/util.c src/util/util.h: not static anymore and export it
* src/libvirt_private.syms: allow access internally

Useful mainly for migration. cpuUpdate changes guest CPU requirements in
the following way:

- match == "strict" || match == "exact"
    - optional features which are supported by host CPU are changed into
      required features
    - optional features which are not supported by host CPU are disabled
    - all other features remain untouched
- match == "minimum"
    - match is changed into "exact"
    - optional features and all features not mentioned in guest CPU
      specification which are supported by host CPU become required
      features
    - other optional features are disabled
    - all other features remain untouched

This ensures that no feature will suddenly disappear from the guest
after migration.

* Fixes per feedback from Dan and Daniel
* Added test datafiles
* Re-disabled JSON flags
* Added code to print the error policy attribute when generating XML
* Re-add empty tag

This patch adds support for L3/L4 filtering using iptables. This adds
support for 'tcp', 'udp', 'icmp', 'igmp', 'sctp' etc. filtering.

As mentioned in the introduction, a .c file provided by this patch
is #include'd into a .c file. This will need work, but should be alright
for review.
Signed-off-by: NStefan Berger <stefanb@us.ibm.com>

This patch implements the core driver and provides
- management functionality for managing the filter XMLs
- compiling the internal filter representation into ebtables rules
- applying ebtables rules on a network (tap,macvtap) interface
- tearing down ebtables rules that were applied on behalf of an
interface
- updating of filters while VMs are running and causing the firewalls to
be rebuilt
- other bits and pieces
Signed-off-by: NStefan Berger <stefanb@us.ibm.com>

This patch adds the implementation of the public API for the network
filtering (ACL) extensions to libvirt.c .
Signed-off-by: NStefan Berger <stefanb@us.ibm.com>

Use the new virDomainUpdateDeviceFlags API to allow the VNC password
to be changed on the fly

* src/internal.h: Define STREQ_NULLABLE() which is like STREQ()
  but does not crash if either argument is NULL, and treats two
  NULLs as equal.
* src/libvirt_private.syms: Export virDomainGraphicsTypeToString
* src/qemu/qemu_driver.c: Support VNC password change on a live
  machine
* src/qemu/qemu_monitor.c: Disable crazy debugging info. Treat a
  NULL password as "" (empty string), allowing passwords to be
  disabled in the monitor

This introduces a new event type

   VIR_DOMAIN_EVENT_ID_GRAPHICS

The same event can be emitted in 3 scenarios

  typedef enum {
      VIR_DOMAIN_EVENT_GRAPHICS_CONNECT = 0,
      VIR_DOMAIN_EVENT_GRAPHICS_INITIALIZE,
      VIR_DOMAIN_EVENT_GRAPHICS_DISCONNECT,
  } virDomainEventGraphicsPhase;

Connect/disconnect are triggered at socket accept/close.
The initialize phase is immediately after the protocol
setup and authentication has completed. ie when the
client is authorized and about to start interacting with
the graphical desktop

This event comes with *a lot* of potential information

 - IP address, port & address family of client
 - IP address, port & address family of server
 - Authentication scheme (arbitrary string)
 - Authenticated subject identity. A subject may have
   multiple identities with some authentication schemes.
   For example, vencrypt+sasl results in a x509dname
   and saslUsername identities.

This results in a very complicated callback :-(

   typedef enum {
      VIR_DOMAIN_EVENT_GRAPHICS_ADDRESS_IPV4,
      VIR_DOMAIN_EVENT_GRAPHICS_ADDRESS_IPV6,
   } virDomainEventGraphicsAddressType;

   struct _virDomainEventGraphicsAddress {
       int family;
       const char *node;
       const char *service;
   };
   typedef struct _virDomainEventGraphicsAddress virDomainEventGraphicsAddress;
   typedef virDomainEventGraphicsAddress *virDomainEventGraphicsAddressPtr;

   struct _virDomainEventGraphicsSubject {
      int nidentity;
      struct {
          const char *type;
          const char *name;
      } *identities;
   };
   typedef struct _virDomainEventGraphicsSubject virDomainEventGraphicsSubject;
   typedef virDomainEventGraphicsSubject *virDomainEventGraphicsSubjectPtr;

   typedef void (*virConnectDomainEventGraphicsCallback)(virConnectPtr conn,
                                                         virDomainPtr dom,
                                                         int phase,
                                                         virDomainEventGraphicsAddressPtr local,
                                                         virDomainEventGraphicsAddressPtr remote,
                                                         const char *authScheme,
                                                         virDomainEventGraphicsSubjectPtr subject,
                                                         void *opaque);

The wire protocol is similarly complex

   struct remote_domain_event_graphics_address {
     int family;
     remote_nonnull_string node;
     remote_nonnull_string service;
   };

   const REMOTE_DOMAIN_EVENT_GRAPHICS_IDENTITY_MAX = 20;

   struct remote_domain_event_graphics_identity {
     remote_nonnull_string type;
     remote_nonnull_string name;
   };

   struct remote_domain_event_graphics_msg {
     remote_nonnull_domain dom;
     int phase;
     remote_domain_event_graphics_address local;
     remote_domain_event_graphics_address remote;
     remote_nonnull_string authScheme;
     remote_domain_event_graphics_identity subject<REMOTE_DOMAIN_EVENT_GRAPHICS_IDENTITY_MAX>;
   };

This is currently implemented in QEMU for the VNC graphics
protocol, but designed to be usable with SPICE graphics in
the future too.

* daemon/remote.c: Dispatch graphics events to client
* examples/domain-events/events-c/event-test.c: Watch for
  graphics events
* include/libvirt/libvirt.h.in: Define new graphics event ID
  and callback signature
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle graphics events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for VNC events and emit a libvirt graphics event
* src/remote/remote_driver.c: Receive and dispatch graphics
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  graphics events
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c: Watch for VNC_CONNECTED,
  VNC_INITIALIZED & VNC_DISCONNETED events from QEMU monitor

This introduces a new event type

   VIR_DOMAIN_EVENT_ID_IO_ERROR

This event includes the action that is about to be taken
as a result of the watchdog triggering

  typedef enum {
     VIR_DOMAIN_EVENT_IO_ERROR_NONE = 0,
     VIR_DOMAIN_EVENT_IO_ERROR_PAUSE,
     VIR_DOMAIN_EVENT_IO_ERROR_REPORT,
  } virDomainEventIOErrorAction;

In addition it has the source path of the disk that had the
error and its unique device alias. It does not include the
target device name (/dev/sda), since this would preclude
triggering IO errors from other file backed devices (eg
serial ports connected to a file)

Thus there is a new callback definition for this event type

typedef void (*virConnectDomainEventIOErrorCallback)(virConnectPtr conn,
                                                     virDomainPtr dom,
                                                     const char *srcPath,
                                                     const char *devAlias,
                                                     int action,
                                                     void *opaque);

This is currently wired up to the QEMU block IO error events

* daemon/remote.c: Dispatch IO error events to client
* examples/domain-events/events-c/event-test.c: Watch for
  IO error events
* include/libvirt/libvirt.h.in: Define new IO error event ID
  and callback signature
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle IO error events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for block IO errors and emit a libvirt IO error event
* src/remote/remote_driver.c: Receive and dispatch IO error
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  IO error events
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c: Watch for BLOCK_IO_ERROR event
  from QEMU monitor

This introduces a new event type

   VIR_DOMAIN_EVENT_ID_WATCHDOG

This event includes the action that is about to be taken
as a result of the watchdog triggering

 typedef enum {
     VIR_DOMAIN_EVENT_WATCHDOG_NONE = 0,
     VIR_DOMAIN_EVENT_WATCHDOG_PAUSE,
     VIR_DOMAIN_EVENT_WATCHDOG_RESET,
     VIR_DOMAIN_EVENT_WATCHDOG_POWEROFF,
     VIR_DOMAIN_EVENT_WATCHDOG_SHUTDOWN,
     VIR_DOMAIN_EVENT_WATCHDOG_DEBUG,
 } virDomainEventWatchdogAction;

Thus there is a new callback definition for this event type

 typedef void (*virConnectDomainEventWatchdogCallback)(virConnectPtr conn,
                                                       virDomainPtr dom,
                                                       int action,
                                                       void *opaque);

* daemon/remote.c: Dispatch watchdog events to client
* examples/domain-events/events-c/event-test.c: Watch for
  watchdog events
* include/libvirt/libvirt.h.in: Define new watchdg event ID
  and callback signature
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle watchdog events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for watchdogs and emit a libvirt watchdog event
* src/remote/remote_driver.c: Receive and dispatch watchdog
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  watchdog events
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c: Watch for WATCHDOG event
  from QEMU monitor

This introduces a new event type

   VIR_DOMAIN_EVENT_ID_RTC_CHANGE

This event includes the new UTC offset measured in seconds.
Thus there is a new callback definition for this event type

 typedef void (*virConnectDomainEventRTCChangeCallback)(virConnectPtr conn,
                                                        virDomainPtr dom,
                                                        long long utcoffset,
                                                        void *opaque);

If the guest XML configuration for the <clock> is set to
offset='variable', then the XML will automatically be
updated with the new UTC offset value. This ensures that
during migration/save/restore the new offset is preserved.

* daemon/remote.c: Dispatch RTC change events to client
* examples/domain-events/events-c/event-test.c: Watch for
  RTC change events
* include/libvirt/libvirt.h.in: Define new RTC change event ID
  and callback signature
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle RTC change events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for RTC changes and emit a libvirt RTC change event
* src/remote/remote_driver.c: Receive and dispatch RTC change
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  RTC change events
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
  src/qemu/qemu_monitor_json.c: Watch for RTC_CHANGE event
  from QEMU monitor

The reboot event is not a normal lifecycle event, since the
virtual machine on the host does not change state. Rather the
guest OS is resetting the virtual CPUs. ie, the QEMU process
does not restart. Thus, this does not belong in the current
lifecycle events callback.

This introduces a new event type

    VIR_DOMAIN_EVENT_ID_REBOOT

It takes no parameters, besides the virDomainPtr, so it can
use the generic callback signature.

* daemon/remote.c: Dispatch reboot events to client
* examples/domain-events/events-c/event-test.c: Watch for
  reboot events
* include/libvirt/libvirt.h.in: Define new reboot event ID
* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Extend API to handle reboot events
* src/qemu/qemu_driver.c: Connect to the QEMU monitor event
  for reboots and emit a libvirt reboot event
* src/remote/remote_driver.c: Receive and dispatch reboot
  events to application
* src/remote/remote_protocol.x: Wire protocol definition for
  reboot events

The current internal domain events API tracks callbacks based on
the function pointer, and only supports lifecycle events. This
adds new internal APIs for registering callbacks for other event
types. These new APIs are postfixed with the word 'ID' to indicate
that they operated based on event ID, instead of hardcoded to
lifecycle events

* src/conf/domain_event.c, src/conf/domain_event.h,
  src/libvirt_private.syms: Add new APIs for handling callbacks
  for non-lifecycle events

This symbol is conditional, it would need to be exported conditional to
work properly with MinGW. So just remove it, as no other driver register
function is listed in the symbols files.

This is necessary for MinGW builds.

Changeset

  commit 5073aa99
  Author: Cole Robinson <crobinso@redhat.com>
  Date:   Mon Jan 11 11:40:46 2010 -0500

Added support for product/vendor based passthrough, but it only
worked at the security driver layer. The main guest XML config
was not updated with the resolved bus/device ID. When the QEMU
argv refactoring removed use of product/vendor, this then broke
launching guests.

THe solution is to move the product/vendor resolution up a layer
into the QEMU driver. So the first thing QEMU does is resolve
the product/vendor to a bus/device and updates the XML config
with this info. The rest of the code, including security drivers
and QEMU argv generated can now rely on bus/device always being
set.

* src/util/hostusb.c, src/util/hostusb.h: Split vendor/product
  resolution code out of usbGetDevice and into usbFindDevice.
  Add accessors for bus/device ID
* src/security/virt-aa-helper.c, src/security/security_selinux.c,
  src/qemu/qemu_security_dac.c: Remove vendor/product from the
  usbGetDevice() calls
* src/qemu/qemu_driver.c: Use usbFindDevice to resolve vendor/product
  into a bus/device ID

This introduces a third option for clock offset synchronization,
that allows an arbitrary / variable adjustment to be set. In
essence the XML contains the time delta in seconds, relative to
UTC.

  <clock offset='variable' adjustment='123465'/>

The difference from 'utc' mode, is that management apps should
track adjustments and preserve them at next reboot.

* docs/schemas/domain.rng: Schema for new clock mode
* src/conf/domain_conf.c, src/conf/domain_conf.h: Parse
  new clock time delta
* src/libvirt_private.syms, src/util/xml.c, src/util/xml.h: Add
  virXPathLongLong() method

The XML will soon be extended to allow more than just a simple
localtime/utc boolean flag. This change replaces the plain
'int localtime' with a separate struct to prepare for future
extension

* src/conf/domain_conf.c, src/conf/domain_conf.h: Add a new
  virDomainClockDef structure
* src/libvirt_private.syms: Export virDomainClockOffsetTypeToString
  and virDomainClockOffsetTypeFromString
* src/qemu/qemu_conf.c, src/vbox/vbox_tmpl.c, src/xen/xend_internal.c,
  src/xen/xm_internal.c: Updated to use new structure for localtime

If the hostname as returned by "gethostname" resolves
to "localhost" (as it does with the broken Fedora-12
installer), then live migration will fail because the
source will try to migrate to itself.  Detect this
situation up-front and abort the live migration before
we do any real work.

* src/util/util.h src/util/util.c: add a new virGetHostnameLocalhost
  with an optional localhost check, and rewire virGetHostname() to use
  it
* src/libvirt_private.syms: expose the new function
* src/qemu/qemu_driver.c: use it in qemudDomainMigratePrepare2()

Add support for virtio-serial by defining a new 'virtio' channel target type
and a virtio-serial controller. Allows the following to be specified in a
domain:

<controller type='virtio-serial' index='0' ports='16' vectors='4'/>
<channel type='pty'>
  <target type='virtio' name='org.linux-kvm.port.0'/>
  <address type='virtio-serial' controller='0' bus='0'/>
</channel>

* docs/schemas/domain.rng: Add virtio-serial controller and virtio
  channel type.
* src/conf/domain_conf.[ch]: Domain parsing/serialization for
  virtio-serial controller and virtio channel.
* tests/qemuxml2xmltest.c
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml: add domain xml
  parsing test
* src/libvirt_private.syms src/qemu/qemu_conf.c:
  virDomainDefAddDiskControllers() renamed to
  virDomainDefAddImplicitControllers()

Remove virDomainDevicePCIAddressEqual and virDomainDeviceDriveAddressEqual,
which are defined but not used anywhere.

* src/conf/domain_conf.[ch] src/libvirt_private.syms: Remove
  virDomainDevicePCIAddressEqual and virDomainDeviceDriveAddressEqual.

Baseline CPU is the best CPU which can be used for a guest on any of the
hosts.

Ad pointed out by Dan Berrange:
So if some thread in libvirtd is currently executing a logging call,
while another thread calls virExec(), that other thread no longer
exists in the child, but its lock is never released. So when the
child then does virLogReset() it deadlocks.

The only way I see to address this, is for the parent process to call
virLogLock(), immediately before fork(), and then virLogUnlock()
afterwards in both parent & child. This will ensure that no other
thread
can be holding the lock across fork().

* src/util/logging.[ch] src/libvirt_private.syms: export virLogLock() and
  virLogUnlock()
* src/util/util.c: lock just before forking and unlock just after - in
  both parent and child.

The virDomainDeviceInfoIterate() function will provide a
convenient way to iterate over all devices in a domain.

* src/conf/domain_conf.c, src/conf/domain_conf.h,
  src/libvirt_private.syms: Add virDomainDeviceInfoIterate()
  function.

Certain hypervisors (like qemu/kvm) map the PCI bar(s) on
the host when doing device passthrough.  This can lead to a race
condition where the hypervisor is still cleaning up the device while
libvirt is trying to re-attach it to the host device driver.  To avoid
this situation, we look through /proc/iomem, and if the hypervisor is
still holding onto the bar (denoted by the string in the matcher variable),
then we can wait around a bit for that to clear up.

v2: Thanks to review by DV, make sure we wait the full timeout per-device
Signed-off-by: NChris Lalancette <clalance@redhat.com>

New pciDeviceIsAssignable() function for checking whether a given PCI
device can be assigned to a guest was added. Currently it only checks
for ACS being enabled on all PCIe switches between root and the PCI
device. In the future, it could be the right place to check whether a
device is unbound or bound to a stub driver.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

This patch introduces the support for giving all devices a short,
unique name, henceforth known as a 'device alias'.  These aliases
are not set by the end user, instead being assigned by the hypervisor
if it decides it want to support this concept.

The QEMU driver sets them whenever using the -device arg syntax
and uses them for improved hotplug/hotunplug. it is the intent
that other APIs (block / interface stats & device hotplug) be
able to accept device alias names in the future.

The XML syntax is

   <alias name="video0"/>

This may appear in any type of device that supports device info.

* src/conf/domain_conf.c, src/conf/domain_conf.h: Add a 'alias'
  field to virDomainDeviceInfo struct & parse/format it in XML
* src/libvirt_private.syms: Export virDomainDefClearDeviceAliases
* src/qemu/qemu_conf.c: Replace use of "nic_name" field with the
  standard device alias
* src/qemu/qemu_driver.c: Clear device aliases at shutdown

The PCI device addresses are only valid while the VM is running,
since they are auto-assigned by QEMU. After shutdown they must
all be cleared. Future QEMU driver enhancement will allow for
persistent PCI address assignment

* src/conf/domain_conf.h, src/conf/domain_conf.c, src/libvirt_private.syms
  Add virDomainDefClearPCIAddresses() method for wiping out auto assigned
  PCI addresses
* src/qemu/qemu_driver.c: Clear PCI addresses at VM shutdown

Existing applications using libvirt are not aware of the disk
controller concept. Thus, after parsing the <disk> definitions
in the XML, it is neccessary to create <controller> elements
to satisfy all requested disks, as per their defined drive
addresses

* src/conf/domain_conf.c, src/conf/domain_conf.h,
  src/libvirt_private.syms: Add virDomainDefAddDiskControllers()
  method for populating disk controllers, and call it after
  parsing disk definitions.
* src/qemu/qemu_conf.c: Call virDomainDefAddDiskControllers()
  when doing ARGV -> XML conversion
* tests/qemuxml2argvdata/qemuxml2argv*.xml: Add disk controller
  data to all data files which don't have it already