https://bugzilla.redhat.com/show_bug.cgi?id=617711 reported that
even with my recent patched to allow <memory unit='G'>1</memory>,
people can still get away with trying <memory>1G</memory> and
silently get <memory unit='KiB'>1</memory> instead.  While
virt-xml-validate catches the error, our C parser did not.

Not to mention that it's always fun to fix bugs while reducing
lines of code.  :)

* src/conf/domain_conf.c (virDomainParseMemory): Check for parse error.
(virDomainDefParseXML): Avoid strtoll.
* src/conf/storage_conf.c (virStorageDefParsePerms): Likewise.
* src/util/xml.c (virXPathLongBase, virXPathULongBase)
(virXPathULongLong, virXPathLongLong): Likewise.

Fix the support for trusted DHCP server in the ebtables code's
hard-coded function applying DHCP only filtering rules:
Rather than using a char * use the more flexible
virNWFilterVarValuePtr that contains the trusted DHCP server(s)
IP address. Process all entries.

Since all callers so far provided NULL as parameter, no changes
are necessary in any other code.

The below patch fixes the following memory leak.

==20624== 24 bytes in 2 blocks are definitely lost in loss record 532 of 1,867
==20624==    at 0x4A05E46: malloc (vg_replace_malloc.c:195)
==20624==    by 0x38EC27FC01: strdup (strdup.c:43)
==20624==    by 0x4EB6BA3: virDomainChrSourceDefCopy (domain_conf.c:1122)
==20624==    by 0x495D76: qemuProcessFindCharDevicePTYs (qemu_process.c:1497)
==20624==    by 0x498321: qemuProcessWaitForMonitor (qemu_process.c:1258)
==20624==    by 0x49B5F9: qemuProcessStart (qemu_process.c:3652)
==20624==    by 0x468B5C: qemuDomainObjStart (qemu_driver.c:4753)
==20624==    by 0x469171: qemuDomainStartWithFlags (qemu_driver.c:4810)
==20624==    by 0x4F21735: virDomainCreate (libvirt.c:8153)
==20624==    by 0x4302BF: remoteDispatchDomainCreateHelper (remote_dispatch.h:852)
==20624==    by 0x4F72C14: virNetServerProgramDispatch (virnetserverprogram.c:416)
==20624==    by 0x4F6D690: virNetServerHandleJob (virnetserver.c:164)
==20624==    by 0x4E8F43D: virThreadPoolWorker (threadpool.c:144)
==20624==    by 0x4E8EAB5: virThreadHelper (threads-pthread.c:161)
==20624==    by 0x38EC606CCA: start_thread (pthread_create.c:301)
==20624==    by 0x38EC2E0C2C: clone (clone.S:115) 

So that a domain xml which doesn't have "placement" specified, but
"cpuset" is specified, could be parsed. And in this case, the
"placement" mode will be set as "static".

As explained in previous patch, numad will balance the affinity
dynamically, so reflecting the cpuset from numad at the first
time doesn't make much case, and may just could cause confusion.

Although it should be harmless to do:
    disk = disk = def->disks[i]
some not-so-wise compilers may fool around.
Besides, such assignment is useless here.

Detected by valgrind. Leaks are introduced in commit b22eaa75.

* src/conf/domain_conf.c (virDomainDiskDefParseXML): fix memory leaks.

How to reproduce?

% make && make -C tests check TESTS=qemuxml2argvtest
% cd tests && valgrind -v --leak-check=full ./qemuxml2argvtest

actual result:

==2143== 12 bytes in 2 blocks are definitely lost in loss record 74 of 179
==2143==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==2143==    by 0x39D90A67DD: xmlStrndup (xmlstring.c:45)
==2143==    by 0x4F5EC0: virDomainDiskDefParseXML (domain_conf.c:3438)
==2143==    by 0x502F00: virDomainDefParseXML (domain_conf.c:8304)
==2143==    by 0x505FE3: virDomainDefParseNode (domain_conf.c:9080)
==2143==    by 0x5069AE: virDomainDefParse (domain_conf.c:9030)
==2143==    by 0x41CBF4: testCompareXMLToArgvHelper (qemuxml2argvtest.c:105)
==2143==    by 0x41E5DD: virtTestRun (testutils.c:145)
==2143==    by 0x416FA3: mymain (qemuxml2argvtest.c:399)
==2143==    by 0x41DCB7: virtTestMain (testutils.c:700)
==2143==    by 0x39CF01ECDC: (below main) (libc-start.c:226)
Signed-off-by: NAlex Jia <ajia@redhat.com>

Since Xen 3.1 the clock=variable semantic is supported. In addition to
qemu/kvm Xen also knows about a variant where the offset is relative to
'localtime' instead of 'utc'.

Extends the libvirt structure with a flag 'basis' to specify, if the
offset is relative to 'localtime' or 'utc'.

Extends the libvirt structure with a flag 'reset' to force the reset
behaviour of 'localtime' and 'utc'; this is needed for backward
compatibility with previous versions of libvirt, since they report
incorrect XML.

Adapt the only user 'qemu' to the new name.
Extend the RelaxNG schema accordingly.
Document the new 'basis' attribute in the HTML documentation.
Adapt test for the new attribute.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

Commit 1b1402b9 introduced a regression.  Since older libvirt versions
would silently round memory up (until the previous patch), but populated
current memory based on querying the guest, it was possible to have
dumpxml show cur > max by the amount of the rounding.  For example, if
a user requested 1048570 KiB memory (just shy of 1GiB), the qemu
driver would actually run with 1048576 KiB, and libvirt 0.9.10 would
output a current that was 6KiB larger than the maximum.  Situations
where this could have an impact include, but are not limited to,
migration from old to new libvirt, managedsave in old libvirt and
start in new libvirt, snapshot creation in old libvirt and revert in
new libvirt - without this patch, the new libvirt would reject the
VM because of the rounding discrepancy.

Fix things by adding a fuzz factor, and silently clamp current down to
maximum in that case, rather than failing to reparse XML for an existing
VM.  From a practical standpoint, this has no user impact: 'virsh
dumpxml' will continue to query the running guest rather than rely on
the incoming xml, which will see the currect current value, and even if
clamping down occurs during parsing, it will be by at most the fuzz
factor of a megabyte alignment, and rounded back up when passed back to
the hypervisor.

Meanwhile, we continue to reject cur > max if the difference is beyond
the fuzz factor of nearest megabyte.  But this is not a real change in
behavior, since with 0.9.10, even though the parser allowed it, later
in the processing stream we would reject it at the qemu layer; so
rejecting it in the parser just moves error detection to a nicer place.

* src/conf/domain_conf.c (virDomainDefParseXML): Don't reject
existing XML.
Based on a report by Zhou Peng.

Regression introduced when we changed types in commit 3e2c3d8f.

We've done this sort of cleanup before (see commit c685993d).

* src/conf/storage_conf.c (virStoragePoolDefFormat)
(virStorageVolTargetDefFormat): Cast gid_t and uid_t.

This patch reverts commit b0e2bb33. Its functionality has been replaced
by commit 3269ee65.

* src/conf/domain_conf.c (virDomainChannelDefCheckABIStability): avoid
  crashing libvirtd due to derefing a NULL pointer.

For details, please see bug:
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=808371Signed-off-by: NAlex Jia <ajia@redhat.com>

libvirt documentation for channels with type 'spicevmc' says that the
'target' child node has:
"an optional attribute name controls how the guest will have access
 to the channel, and defaults to name='com.redhat.spice.0'."

However, this default value is never set in libvirt code base,
there's only a check in qemu_command.c to error out if the name
attribute doesn't have the expected value (if it's set).

This commit sets a default target name for spicevmc channels during
the domain configuration parsing so that the code agrees with the
documentation.

Pass argv to the init binary of LXC, using a new <initarg> element.

* docs/formatdomain.html.in: Document <os> usage for containers
* docs/schemas/domaincommon.rng: Add <initarg> element
* src/conf/domain_conf.c, src/conf/domain_conf.h: parsing and
  formatting of <initarg>
* src/lxc/lxc_container.c: Setup LXC argv
* tests/Makefile.am, tests/lxcxml2xmldata/lxc-systemd.xml,
  tests/lxcxml2xmltest.c, tests/testutilslxc.c,
  tests/testutilslxc.h: Test parsing/formatting of LXC related
  XML parts

Return statements with parameter enclosed in parentheses were modified
and parentheses were removed. The whole change was scripted, here is how:

List of files was obtained using this command:
git grep -l -e '\<return\s*([^()]*\(([^()]*)[^()]*\)*)\s*;' |             \
grep -e '\.[ch]$' -e '\.py$'

Found files were modified with this command:
sed -i -e                                                                 \
's_^\(.*\<return\)\s*(\(\([^()]*([^()]*)[^()]*\)*\))\s*\(;.*$\)_\1 \2\4_' \
-e 's_^\(.*\<return\)\s*(\([^()]*\))\s*\(;.*$\)_\1 \2\3_'

Then checked for nonsense.

The whole command looks like this:
git grep -l -e '\<return\s*([^()]*\(([^()]*)[^()]*\)*)\s*;' |             \
grep -e '\.[ch]$' -e '\.py$' | xargs sed -i -e                            \
's_^\(.*\<return\)\s*(\(\([^()]*([^()]*)[^()]*\)*\))\s*\(;.*$\)_\1 \2\4_' \
-e 's_^\(.*\<return\)\s*(\([^()]*\))\s*\(;.*$\)_\1 \2\3_'

This introduces a new domain state pmsuspended to represent
the domain which has been suspended by guest power management,
e.g. (entered itno s3 state). Because a "running" state could
be confused in this case, one will see the guest is paused
actually while playing. And state "paused" is for the domain
which was paused by virDomainSuspend.

This patch introduces a new event type for the QMP event
SUSPEND:

    VIR_DOMAIN_EVENT_ID_PMSUSPEND

The event doesn't take any data, but considering there might
be reason for wakeup in future, the callback definition is:

typedef void
(*virConnectDomainEventSuspendCallback)(virConnectPtr conn,
                                        virDomainPtr dom,
                                        int reason,
                                        void *opaque);

"reason" is unused currently, always passes "0".

This patch introduces a new event type for the QMP event
WAKEUP:

    VIR_DOMAIN_EVENT_ID_PMWAKEUP

The event doesn't take any data, but considering there might
be reason for wakeup in future, the callback definition is:

typedef void
(*virConnectDomainEventWakeupCallback)(virConnectPtr conn,
                                       virDomainPtr dom,
                                       int reason,
                                       void *opaque);

"reason" is unused currently, always passes "0".

The "tray" is only allowed for removable disks, i.e. CDROM and
Floppy disks.

This patch introduces a new event type for the QMP event
DEVICE_TRAY_MOVED, which occurs when the tray of a removable
disk is moved (i.e opened or closed):

    VIR_DOMAIN_EVENT_ID_TRAY_CHANGE

The event's data includes the device alias and the reason
for tray status' changing, which indicates why the tray
status was changed. Thus the callback definition for the event
is:

enum {
    VIR_DOMAIN_EVENT_TRAY_CHANGE_OPEN = 0,
    VIR_DOMAIN_EVENT_TRAY_CHANGE_CLOSE,

\#ifdef VIR_ENUM_SENTINELS
    VIR_DOMAIN_EVENT_TRAY_CHANGE_LAST
\#endif
} virDomainEventTrayChangeReason;

typedef void
(*virConnectDomainEventTrayChangeCallback)(virConnectPtr conn,
                                           virDomainPtr dom,
                                           const char *devAlias,
                                           int reason,
                                           void *opaque);

A few times libvirt users manually setting mac addresses have
complained of a networking failure that ends up being due to a multicast
mac address being used for a guest interface. This patch prevents that
by logging an error and failing if a multicast mac address is
encountered in each of the three following cases:

1) domain xml <interface> mac address.
2) network xml bridge mac address.
3) network xml dhcp/host mac address.

There are several other places where a mac address can be input that
aren't controlled in this manner because failure to do so has no
consequences (e.g., if the address will be used to search through
existing interfaces for a match).

The RNG has been updated to add multiMacAddr and uniMacAddr along with
the existing macAddr, and macAddr was switched to uniMacAddr where
appropriate.

If an error was encountered parsing a dhcp host entry mac address or
name, parsing would continue and log a less descriptive error that
might make it more difficult to notice the true nature of the problem.

This patch returns immediately on logging the first error.

If no <interface> elements are included in an LXC guest XML
description, then the LXC guest will just see the host's
network interfaces. It is desirable to be able to hide the
host interfaces, without having to define any guest interfaces.

This patch introduces a new feature flag <privnet/> to allow
forcing of a private network namespace for LXC. In the future
I also anticipate that we will add <privuser/> to force a
private user ID namespace.

* src/conf/domain_conf.c, src/conf/domain_conf.h: Add support
  for <privnet/> feature. Auto-set <privnet> if any <interface>
  devices are defined
* src/lxc/lxc_container.c: Honour request for private network
  namespace

numad is an user-level daemon that monitors NUMA topology and
processes resource consumption to facilitate good NUMA resource
alignment of applications/virtual machines to improve performance
and minimize cost of remote memory latencies. It provides a
pre-placement advisory interface, so significant processes can
be pre-bound to nodes with sufficient available resources.

More details: http://fedoraproject.org/wiki/Features/numad

"numad -w ncpus:memory_amount" is the advisory interface numad
provides currently.

This patch add the support by introducing a new XML attribute
for <vcpu>. e.g.

  <vcpu placement="auto">4</vcpu>
  <vcpu placement="static" cpuset="1-10^6">4</vcpu>

The returned advisory nodeset from numad will be printed
in domain's dumped XML. e.g.
  <vcpu placement="auto" cpuset="1-10^6">4</vcpu>

If placement is "auto", the number of vcpus and the current
memory amount specified in domain XML will be used for numad
command line (numad uses MB for memory amount):
  numad -w $num_of_vcpus:$current_memory_amount / 1024

The advisory nodeset returned from numad will be used to set
domain process CPU affinity then. (e.g. qemuProcessInitCpuAffinity).

If the user specifies both CPU affinity policy (e.g.
(<vcpu cpuset="1-10,^7,^8">4</vcpu>) and placement == "auto"
the specified CPU affinity will be overridden.

Only QEMU/KVM drivers support it now.

See docs update in patch for more details.

Even though we say in documentation setting (tls-)port to -1 is legacy
compat style for enabling autoport, we're roughly doing this for VNC.
However, in case of SPICE auto enable autoport iff both port & tlsPort
are equal -1 as documentation says autoport plays with both.

When host-model and host-passthrouh CPU modes were introduced, qemu
driver was properly modify to update guest CPU definition during
migration so that we use the right CPU at the destination. However,
similar treatment is needed for (managed)save and snapshots since they
need to save the exact CPU so that a domain can be properly restored.
To avoid repetition of such situation, all places that need live XML
share the code which generates it.

As a side effect, this patch fixes error reporting from
qemuDomainSnapshotWriteMetadata().

virNetworkDNSHostsDefParseXML was calling VIR_ALLOC(def->hosts) if
def->hosts was NULL. This is a waste of time, though, since
VIR_REALLOC_N is called a few lines further down, prior to any use of
def->hosts. (initializing def->nhosts to 0 is also redundant, because
the newly allocated memory will always be cleared to all 0's anyway).

spice agent-mouse support

Usage:
  <graphics type='spice'>
    <mouse mode='client'|'server'/>
  <graphics/>
Signed-off-by: NOsier Yang <jyang@redhat.com>

There are several functions in domain_conf.c that remove a device
object from the domain's list of that object type, but don't free the
object or return it to the caller to free. In many cases this isn't a
problem because the caller already had a pointer to the object and
frees it afterward, but in several cases the removed object was just
left floating around with no references to it.

In particular, the function qemuDomainDetachDeviceConfig() calls
functions to locate and remove net (virDomainNetRemoveByMac), disk
(virDomainDiskRemoveByName()), and lease (virDomainLeaseRemove())
devices, but neither it nor its caller qemuDomainModifyDeviceConfig()
ever obtain a pointer to the device being removed, much less free it.

This patch modifies the following "remove" functions to return a
pointer to the device object being removed from the domain device
arrays, to give the caller the option of freeing the device object
using that pointer if needed. In places where the object was
previously leaked, it is now freed:

  virDomainDiskRemove
  virDomainDiskRemoveByName
  virDomainNetRemove
  virDomainNetRemoveByMac
  virDomainHostdevRemove
  virDomainLeaseRemove
  virDomainLeaseRemoveAt

The functions that had been leaking:

  libxlDomainDetachConfig - leaked a virDomainDiskDef
  qemuDomainDetachDeviceConfig - could leak a virDomainDiskDef,
                            a virDomainNetDef, or a
                            virDomainLeaseDef
  qemuDomainDetachLease   - leaked a virDomainLeaseDef

It will be used in a different file in an upcoming patch.

Some members are generated during XML parse (e.g. MAC address of
an interface); However, with current implementation, if we
are plugging a device both to persistent and live config,
we parse given XML twice: first time for live, second for config.
This is wrong then as the second time we are not guaranteed
to generate same values as we did for the first time.
To prevent that we need to create a copy of DeviceDefPtr;
This is done through format/parse process instead of writing
functions for deep copy as it is easier to maintain:
adding new field to any virDomain*DefPtr doesn't require change
of copying function.

Output is still in kibibytes, but input can now be in different
scales for ease of typing.

* src/conf/domain_conf.c (virDomainParseMemory): New helper.
(virDomainDefParseXML): Use it when parsing.
* docs/schemas/domaincommon.rng: Expand XML; rename memoryKBElement
to memoryElement and update callers.
* docs/formatdomain.html.in (elementsMemoryAllocation): Document
scaling.
* tests/qemuxml2argvdata/qemuxml2argv-memtune.xml: Adjust test.
* tests/qemuxml2xmltest.c: Likewise.
* tests/qemuxml2xmloutdata/qemuxml2xmlout-memtune.xml: New file.

Using 'unsigned long' for memory values is risky on 32-bit platforms,
as a PAE guest can have more than 4GiB memory.  Our API is
(unfortunately) locked at 'unsigned long' and a scale of 1024, but
the rest of our system should consistently use 64-bit values,
especially since the previous patch centralized overflow checking.

* src/conf/domain_conf.h (_virDomainDef): Always use 64-bit values
for memory.  Change hugepage_backed to a bool.
* src/conf/domain_conf.c (virDomainDefParseXML)
(virDomainDefCheckABIStability, virDomainDefFormatInternal): Fix
clients.
* src/vmx/vmx.c (virVMXFormatConfig): Likewise.
* src/xenxs/xen_sxpr.c (xenParseSxpr, xenFormatSxpr): Likewise.
* src/xenxs/xen_xm.c (xenXMConfigGetULongLong): New function.
(xenXMConfigGetULong, xenXMConfigSetInt): Avoid truncation.
(xenParseXM, xenFormatXM): Fix clients.
* src/phyp/phyp_driver.c (phypBuildLpar): Likewise.
* src/openvz/openvz_driver.c (openvzDomainSetMemoryInternal):
Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainDefineXML): Likewise.
* src/qemu/qemu_command.c (qemuBuildCommandLine): Likewise.
* src/qemu/qemu_process.c (qemuProcessStart): Likewise.
* src/qemu/qemu_monitor.h (qemuMonitorGetBalloonInfo): Likewise.
* src/qemu/qemu_monitor_text.h (qemuMonitorTextGetBalloonInfo):
Likewise.
* src/qemu/qemu_monitor_text.c (qemuMonitorTextGetBalloonInfo):
Likewise.
* src/qemu/qemu_monitor_json.h (qemuMonitorJSONGetBalloonInfo):
Likewise.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONGetBalloonInfo):
Likewise.
* src/qemu/qemu_driver.c (qemudDomainGetInfo)
(qemuDomainGetXMLDesc): Likewise.
* src/uml/uml_conf.c (umlBuildCommandLine): Likewise.

The test domain allows <memory>0</memory>, but the RNG was stating
that memory had to be at least 4096000 bytes.  Hypervisors should
enforce their own limits, rather than complicating the RNG.

Meanwhile, some copy and paste had introduced some fishy constructs
in various unit tests.

* docs/schemas/domaincommon.rng (memoryKB, memoryKBElement): Drop
limit that isn't enforced in code.
* src/conf/domain_conf.c (virDomainDefParseXML): Require current
<= maximum.
* tests/qemuxml2argvdata/*.xml: Fix offenders.

Disk manufacturers are fond of quoting sizes in powers of 10,
rather than powers of 2 (after all, 2.1 GB sounds larger than
2.0 GiB, even though the exact opposite is true).  So, we might
as well follow coreutils' lead in supporting three types of
suffix: single letter ${u} (which we already had) and ${u}iB
for the power of 2, and ${u}B for power of 10.

Additionally, it is impossible to create a file with more than
2**63 bytes, since off_t is signed (if you have enough storage
to even create one 8EiB file, I'm jealous).  This now reports
failure up front rather than down the road when the kernel
finally refuses an impossible size.

* docs/schemas/basictypes.rng (unit): Add suffixes.
* src/conf/storage_conf.c (virStorageSize): Use new function.
* docs/formatstorage.html.in: Document it.
* tests/storagevolxml2xmlin/vol-file-backing.xml: Test it.
* tests/storagevolxml2xmlin/vol-file.xml: Likewise.

Make it obvious to 'dumpxml' readers what unit we are using,
since our default of KiB for memory (1024) differs from qemu's
default of MiB; and differs from our use of bytes for storage.

Tests were updated via:

$ find tests/*data tests/*out -name '*.xml' | \
  xargs sed -i 's/<\(memory\|currentMemory\|hard_limit\|soft_limit\|min_guarantee\|swap_hard_limit\)>/<\1 unit='"'KiB'>/"
$ find tests/*data tests/*out -name '*.xml' | \
  xargs sed -i 's/<\(capacity\|allocation\|available\)>/<\1 unit='"'bytes'>/"

followed by a few fixes for the stragglers.

Note that with this patch, the RNG for <memory> still forbids
validation of anything except unit='KiB', since the code silently
ignores the attribute; a later patch will expand <memory> to allow
scaled input in the code and update the RNG to match.

* docs/schemas/basictypes.rng (unit): Add 'bytes'.
(scaledInteger): New define.
* docs/schemas/storagevol.rng (sizing): Use it.
* docs/schemas/storagepool.rng (sizing): Likewise.
* docs/schemas/domaincommon.rng (memoryKBElement): New define; use
for memory elements.
* src/conf/storage_conf.c (virStoragePoolDefFormat)
(virStorageVolDefFormat): Likewise.
* src/conf/domain_conf.h (_virDomainDef): Document unit used
internally.
* src/conf/storage_conf.h (_virStoragePoolDef, _virStorageVolDef):
Likewise.
* tests/*data/*.xml: Update all tests.
* tests/*out/*.xml: Likewise.
* tests/define-dev-segfault: Likewise.
* tests/openvzutilstest.c (testReadNetworkConf): Likewise.
* tests/qemuargv2xmltest.c (blankProblemElements): Likewise.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=800762

This exact code is duplicated in qemuDomainDetachNetDevice().

This patch makes sure that each network device ("interface") of
type='hostdev' appears on both the hostdevs list and the nets list of
the virDomainDef, and it modifies the qemu driver startup code so that
these devices will be presented to qemu on the commandline as hostdevs
rather than as network devices.

It does not add support for hotplug of these type of devices, or code
to honor the <mac address> or <virtualport> given in the config (both
of those will be done in separate patches).

Once each device is placed on both lists, much of what this patch does
is modify places in the code that traverse all the device lists so
that these hybrid devices are only acted on once - either along with
the other hostdevs, or along with the other network interfaces. (In
many cases, only one of the lists is traversed / a specific operation
is performed on only one type of device. In those instances, the code
can remain unchanged.)

There is one special case - when building the commandline, interfaces
are allowed to proceed all the way through
networkAllocateActualDevice() before deciding to skip the rest of
netdev-specific processing - this is so that (once we have support for
networks with pools of hostdev devices) we can get the actual device
allocated, then rely on the loop processing all hostdevs to generate
the correct commandline.

(NB: <interface type='hostdev'> is only supported for PCI network
devices that are SR-IOV Virtual Functions (VF). Standard PCI[e] and
USB devices, and even the Physical Functions (PF) of SR-IOV devices
can only be assigned to a guest using the more basic <hostdev> device
entry. This limitation is mostly due to the fact that non-SR-IOV
ethernet devices tend to lose mac address configuration whenever the
card is reset, which happens when a card is assigned to a guest;
SR-IOV VFs fortunately don't suffer the same problem.)

This is the new interface type that sets up an SR-IOV PCI network
device to be assigned to the guest with PCI passthrough after
initializing some network device-specific things from the config
(e.g. MAC address, virtualport profile parameters). Here is an example
of the syntax:

  <interface type='hostdev' managed='yes'>
    <source>
      <address type='pci' domain='0' bus='0' slot='4' function='3'/>
    </source>
    <mac address='00:11:22:33:44:55'/>
    <address type='pci' domain='0' bus='0' slot='7' function='0'/>
  </interface>

This would assign the PCI card from bus 0 slot 4 function 3 on the
host, to bus 0 slot 7 function 0 on the guest, but would first set the
MAC address of the card to 00:11:22:33:44:55.

NB: The parser and formatter don't care if the PCI card being
specified is a standard single function network adapter, or a virtual
function (VF) of an SR-IOV capable network adapter, but the upcoming
code that implements the back end of this config will work *only* with
SR-IOV VFs. This is because modifying the mac address of a standard
network adapter prior to assigning it to a guest is pointless - part
of the device reset that occurs during that process will reset the MAC
address to the value programmed into the card's firmware.

Although it's not supported by any of libvirt's hypervisor drivers,
usb network hostdevs are also supported in the parser and formatter
for completeness and consistency. <source> syntax is identical to that
for plain <hostdev> devices, except that the <address> element should
have "type='usb'" added if bus/device are specified:

  <interface type='hostdev'>
    <source>
      <address type='usb' bus='0' device='4'/>
    </source>
    <mac address='00:11:22:33:44:55'/>
  </interface>

If the vendor/product form of usb specification is used, type='usb'
is implied:

  <interface type='hostdev'>
    <source>
      <vendor id='0x0012'/>
      <product id='0x24dd'/>
    </source>
    <mac address='00:11:22:33:44:55'/>
  </interface>

Again, the upcoming patch to fill in the backend of this functionality
will log an error and fail with "Unsupported Config" if you actually
try to assign a USB network adapter to a guest using <interface
type='hostdev'> - just use a standard <hostdev> entry in that case
(and also for single-port PCI adapters).