qemu: Don't use virDomainDefFormat* directly

Always use appropriate qemuDomain{,Def}Format wrapper since it may do
some additional magic based on the flags.
qemu: Emit compatible XML when migrating a domain

When we added the default USB controller into domain XML, we efficiently
broke migration to older versions of libvirt that didn't support USB
controllers at all (0.9.4 and earlier) even for domains that don't use
anything that the older libvirt can't provide. We still want to present
the default USB controller in any XML seen by a user/app but we can
safely remove it from the domain XML used during migration. If we are
migrating to a new enough libvirt, it will add the controller XML back,
while older libvirt won't be confused with it although it will still
tell qemu to create the controller.

Similar approach can be used in the future whenever we find out we
always enabled some kind of device without properly advertising it in
domain XML.
docs: Add 'maintenance releases' link in 'News' sidebar
rpm: Handle different source URLs for maint releases
usb: create functions to search usb device accurately

usbFindDevice():get usb device according to
                idVendor, idProduct, bus, device
                it is the exact match of the four parameters

usbFindDeviceByBus():get usb device according to bus, device
                  it returns only one usb device same as usbFindDevice

usbFindDeviceByVendor():get usb device according to idVendor,idProduct
                     it probably returns multiple usb devices.

usbDeviceSearch(): a helper function to do the actual search
qemu: call usb search function for hostdev initialization and hotplug

src/qemu/qemu_hostdev.c:
refactor qemuPrepareHostdevUSBDevices function, make it focus on
adding usb device to activeUsbHostdevs after check. After that,
the usb hotplug function qemuDomainAttachHostDevice also could use
it.
expand qemuPrepareHostUSBDevices to perform the usb search,
rollback on failure.

src/qemu/qemu_hotplug.c:
If there are multiple usb devices available with same vendorID and productID,
but with different value of "bus, device", we give an error to let user
use <address> to specify the desired one.
openvz: simplify openvzDomainDefineCmd by using virCommandPtr
util: fix libvirtd startup failure due to netlink error

This is part of the solution to the problem detailed in:

  https://bugzilla.redhat.com/show_bug.cgi?id=816465

and further detailed in

  https://www.redhat.com/archives/libvir-list/2012-May/msg00202.htm

A short explanation is included in the comments of the patch itself.

Note that this patch by itself breaks communication between lldpad and
libvirtd, so the other 3 patches in the series must be applied at the
same time as this patch.
util: allow specifying both src and dst pid in virNetlinkCommand

Until now, virNetlinkCommand has assumed that the nl_pid in the source
address of outgoing netlink messages should always be the return value
of getpid(). In most cases it actually doesn't matter, but in the case
of communication with lldpad, lldpad saves this info and later uses it
to send netlink messages back to libvirt. A recent patch to fix Bug
816465 changed the order of the universe such that the netlink event
service socket is no longer bound with nl_pid == getpid(), so lldpad
could no longer send unsolicited messages to libvirtd. Adding src_pid
as an argument to virNetlinkCommand() is the first step in notifying
lldpad of the proper address of the netlink event service socket.
util: function to get local nl_pid used by netlink event socket

This value will be needed to set the src_pid when sending netlink
messages to lldpad. It is part of the solution to:

  https://bugzilla.redhat.com/show_bug.cgi?id=816465

Note that libnl's port generation algorithm guarantees that the
nl_socket_get_local_port() will always be > 0 (since it is "getpid() +
(n << 22>" where n is always < 1024), so it is okay to cast the
uint32_t to int (thus allowing us to use -1 as an error sentinel).
util: set src_pid for virNetlinkCommand when appropriate

Until now, the nl_pid of the source address of every message sent by
virNetlinkCommand has been set to the value of getpid(). Most of the
time this doesn't matter, and in the one case where it does
(communication with lldpad), it previously was the proper thing to do,
because the netlink event service (which listens on a netlink socket
for unsolicited messages from lldpad) coincidentally always happened
to bind with a local nl_pid == getpid().

With the fix for:

  https://bugzilla.redhat.com/show_bug.cgi?id=816465

that particular nl_pid is now effectively a reserved value, so the
netlink event service will always bind to something else
(coincidentally "getpid() + (1 << 22)", but it really could be
anything). The result is that communication between lldpad and
libvirtd is broken (lldpad gets a "disconnected" error when it tries
to send a directed message).

The solution to this problem caused by a solution, is to query the
netlink event service's nlhandle for its "local_port", and send that
as the source nl_pid (but only when sending to lldpad, of course - in
other cases we maintain the old behavior of sending getpid()).

There are two cases where a message is being directed at lldpad - one
in virNetDevLinkDump, and one in virNetDevVPortProfileOpSetLink.

The case of virNetDevVPortProfileOpSetLink is simplest to explain -
only if !nltarget_kernel, i.e. the message isn't targetted for the
kernel, is the dst_pid set (by calling
virNetDevVPortProfileGetLldpadPid()), so only in that case do we call
virNetlinkEventServiceLocalPid() to set src_pid.

For virNetDevLinkDump, it's a bit more complicated. The call to
virNetDevVPortProfileGetLldpadPid() was effectively up one level (in
virNetDevVPortProfileOpCommon), although obscured by an unnecessary
passing of a function pointer. This patch removes the function
pointer, and calls virNetDevVPortProfileGetLldpadPid() directly in
virNetDevVPortProfileOpCommon - if it's doing this, it knows that it
should also call virNetlinkEventServiceLocalPid() to set src_pid too;
then it just passes src_pid and dst_pid down to
virNetDevLinkDump. Since (src_pid == 0 && dst_pid == 0) implies that
the kernel is the destination, there is no longer any need to send
nltarget_kernel as an arg to virNetDevLinkDump, so it's been removed.

The disparity between src_pid being int and dst_pid being uint32_t may
be a bit disconcerting to some, but I didn't want to complicate
virNetlinkEventServiceLocalPid() by having status returned separately
from the value.
virsh: avoid heap corruption leading to virsh abort

* tools/virsh.c (vshParseSnapshotDiskspec): Fix off-by-3 memmove
that would corrupt heap when parsing escaped --diskspec comma.
Bug introduced via commit v0.9.4-260-g35d52b5.
build: avoid link failure on Windows

We only know -lpthread exists on platforms where we build
threads-pthread.c; but when we build threads-win32.c, LIB_PTHREAD
is empty.

* tests/Makefile.am (shunloadtest_LDADD): Use correct library.
domain_conf: add "usbredir" to list of valid spice channels

Add "usbredir" channel to list of recognized spice channels.

RHBZ: 819498

Signed-off-by: Alon Levy <alevy@redhat.com>
domain_conf: add "default" to list of valid spice channels

qemu's behavior in this case is to change the spice server behavior to
require secure connection to any channel not otherwise specified as
being in plaintext mode. libvirt doesn't currently allow requesting this
(via plaintext-channel=<channel name>).

RHBZ: 819499

Signed-off-by: Alon Levy <alevy@redhat.com>
tests: add some self-documentation to tests

Alon tried './qemuxml2argvtest --help' to figure out a test failure,
but it didn't help.  The information is in HACKING, but it doesn't
hurt to make the tests also provide their own help.

Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
snapshot: allow block devices past cgroup

It turns out that when cgroups are enabled, the use of a block device
for a snapshot target was failing with EPERM due to libvirt failing
to add the block device to the cgroup whitelist.  See also
https://bugzilla.redhat.com/show_bug.cgi?id=810200

* src/qemu/qemu_driver.c
(qemuDomainSnapshotCreateSingleDiskActive)
(qemuDomainSnapshotUndoSingleDiskActive): Account for cgroup.
(qemuDomainSnapshotCreateDiskActive): Update caller.
numad: Set memory policy from numad advisory nodeset

Though numad will manage the memory allocation of task dynamically,
it wants management application (libvirt) to pre-set the memory
policy according to the advisory nodeset returned from querying numad,
(just like pre-bind CPU nodeset for domain process), and thus the
performance could benefit much more from it.

This patch introduces new XML tag 'placement', value 'auto' indicates
whether to set the memory policy with the advisory nodeset from numad,
and its value defaults to the value of <vcpu> placement, or 'static'
if 'nodeset' is specified. Example of the new XML tag's usage:

  <numatune>
    <memory placement='auto' mode='interleave'/>
  </numatune>

Just like what current "numatune" does, the 'auto' numa memory policy
setting uses libnuma's API too.

If <vcpu> "placement" is "auto", and <numatune> is not specified
explicitly, a default <numatume> will be added with "placement"
set as "auto", and "mode" set as "strict".

The following XML can now fully drive numad:

1) <vcpu> placement is 'auto', no <numatune> is specified.

   <vcpu placement='auto'>10</vcpu>

2) <vcpu> placement is 'auto', no 'placement' is specified for
   <numatune>.

   <vcpu placement='auto'>10</vcpu>
   <numatune>
     <memory mode='interleave'/>
   </numatune>

And it's also able to control the CPU placement and memory policy
independently. e.g.

1) <vcpu> placement is 'auto', and <numatune> placement is 'static'

   <vcpu placement='auto'>10</vcpu>
   <numatune>
     <memory mode='strict' nodeset='0-10,^7'/>
   </numatune>

2) <vcpu> placement is 'static', and <numatune> placement is 'auto'

   <vcpu placement='static' cpuset='0-24,^12'>10</vcpu>
   <numatune>
     <memory mode='interleave' placement='auto'/>
   </numatume>

A follow up patch will change the XML formatting codes to always output
'placement' for <vcpu>, even it's 'static'.
numad: Copy 'placement' of <numatune> to <vcpu> by default

With this patch, one can also fully drive numad by:

  <vcpu>2</vcpu>
  <numatune>
    <memory placement='auto'/>
  </numatune>

New tests are added.
numad: Always output 'placement' of <vcpu>

<vcpu> is not an optional node. The value for its 'placement'
actually always defaults to 'static' in the underlying codes.
(Even no 'cpuset' and 'placement' is specified, the domain
process will be pinned to all the available pCPUs).