Commit Graph

19447 Commits

Author SHA1 Message Date
Marc-André Lureau
208abbcbd7 docs: add domain vmport feature
A new feature that can be turned on or off.

The QEMU machine vmport option allows to set the VMWare IO port
emulation. This emulation is useful for absolute pointer input when the
guest has vmware input drivers, and is enabled by default for kvm.

However it is unnecessary for Spice-enabled VM, since the agent already
handles absolute pointer and multi-monitors. Furthermore, it prevents
Spice from switching to relative input since the regular ps/2 pointer
driver is replaced by the vmware driver. It is thus advised to disable
vmport when using a Spice VM. This will permit the Spice client to
switch from absolute to relative pointer, as it may be required for
certain games or applications.
2015-05-04 13:19:38 +02:00
Jiri Denemark
811fb55988 Bump version to 1.2.16 for new dev cycle 2015-05-04 13:04:39 +02:00
Luyao Huang
3f7cad7a8f qemu: fix the vm deadlock when deleting a nonexistent iothread
https://bugzilla.redhat.com/show_bug.cgi?id=1218145

Jump to endjob instead of cleanup to fix this deadlock.

Signed-off-by: Luyao Huang <lhuang@redhat.com>
2015-05-04 12:18:55 +02:00
Luyao Huang
3dae162db7 tools: fix the wrong check when use virsh setvcpus --maximum
The --maximum option wasn't properly parsed and the equivalent flag
wasn't set.  Fix this bug and also rewrite the way we check this option
by using new macro.  The new approach is that --maximum requires
--config, no other combination is allowed, because they don't make sense.

The new error will be:

 # virsh setvcpus test --maximum 10
 error: Option --config is required by option --maximum

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1204033

Signed-off-by: Luyao Huang <lhuang@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 10:26:57 +02:00
Pavel Hrdina
170fb72c70 virsh: introduce new macros to help check flag requirements
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:01 +02:00
Pavel Hrdina
28ca8520bb qemu: use new macros for setvcpus to check flags and cleanup the code
Now that we have macros for exclusive flags and flag requirements we can
use them to cleanup the code for setvcpus and error out for all wrong
flag combination.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:01 +02:00
Pavel Hrdina
6e3f9cbc9c use new macro helpers to check flag requirements
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:01 +02:00
Pavel Hrdina
ff3f93bcc2 use new macro helpers to check exclusive flags
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:00 +02:00
Pavel Hrdina
0fb03395a0 internal: introduce macro helpers to check flag requirements
Similar to VIR_EXLUSIVE_FLAGS, it will error out if flag requirement is
not met.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:00 +02:00
Pavel Hrdina
e86a94ee4c internal: introduce macro helpers to reject exclusive flags
Inspired by commit 7e437ee7 that introduced similar macros for virsh
commands so we don't have to repeat the same code all over.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-05-04 09:20:00 +02:00
Daniel Veillard
b978b85b24 Release of libvirt-1.2.15
- docs/news.html.in libvirt.spec.in: update for the release
- po/*.po*: regenerated
2015-05-04 11:43:04 +08:00
John Ferlan
63a368012d qemu: Fix bus and lun checks when scsi-disk.channel not present
Found by Laine and discussed a bit on internal IRC.

Commit id c56fe7f1d6 added support for creating a command line to support
scsi-disk.channel.

Series was here:
http://www.redhat.com/archives/libvir-list/2012-February/msg01052.html

Which pointed to a design proposal here:
http://permalink.gmane.org/gmane.comp.emulators.libvirt/50428

Which states (in part):

Libvirt should check for the QEMU "scsi-disk.channel" property.  If it
is unavailable, QEMU will only support channel=lun=0 and 0<=target<=7.

However, the check added was ensuring that bus != lun *and* bus != 0. So
if bus == lun and both were non zero, we'd never make the second check.
Changing this to an *or* check fixes the check, but still is less readable
than the just checking each for 0
2015-04-30 16:21:38 -04:00
Pavel Hrdina
bb3cc43cd4 main: add new generated files to .gitignore
This means new libxl-lockd.conf and libxl-sanlock.conf

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-04-30 18:39:34 +02:00
Pavel Hrdina
62b18d981c rpm-build: update %files section for libxl
Recent commit 198cc1d3 introduced integration of lockd and sanlock into
libxl, but forget to update libvirt.spec.in to also list new files
distributed via package.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-04-30 17:21:07 +02:00
Peter Krempa
f06d7daaa9 qemu: blockjob: Call qemuDomainSupportsBlockJobs only on online VMs
Since the qemu capabilities are not initialized for offline VMs the
caller might get suboptimal error message:

$ virsh blockjob VM PATH --bandwidth 1
error: unsupported configuration: block jobs not supported with this QEMU binary

Move the checks after we make sure that the VM is alive.
2015-04-30 16:46:42 +02:00
Jiri Denemark
6280294574 qemu: Check address type for USB disks
Only USB addresses are allowed for USB disks. Report an error if another
address is configured.

https://bugzilla.redhat.com/show_bug.cgi?id=1043436

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
2015-04-30 15:34:57 +02:00
Jiri Denemark
01ecee247a cpu: Honor vendor_id override in host-model
https://bugzilla.redhat.com/show_bug.cgi?id=858147

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
2015-04-30 15:34:57 +02:00
Ján Tomko
a41b1f196c iscsi: do not fail to stop a stopped pool
Just as we allow stopping filesystem pools when they were unmounted
externally, do not fail to stop an iscsi pool when someone else
closed the session externally.

Reported at:
https://bugzilla.redhat.com/show_bug.cgi?id=1171984
2015-04-30 13:05:10 +02:00
Jim Fehlig
198cc1d339 libxl: provide integration with lock manager
Provide integration with libvirt's lock manager in the libxl driver.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
2015-04-29 10:51:36 -06:00
Cole Robinson
066f7c7c3a domain: conf: Drop unused OSTYPE_AIX
The phyp driver stuffed it into a DomainDefPtr during its attachdevice
routine, but the value is never advertised via capabilities so it should
be safe to drop.

Have the phyp driver use OSTYPE_LINUX, which is what it advertises via
capabilities.
2015-04-29 09:42:26 -04:00
Michael Chapman
99725f946c qemu: migration: use sync block job helpers
In qemuMigrationDriveMirror we can start all disk mirrors in parallel.
We wait until they are all ready, or one of them aborts.

In qemuMigrationCancelDriveMirror, we wait until all mirrors are
properly stopped. This is necessary to ensure that destination VM is
fully in sync with the (paused) source VM.

If a drive mirror can not be cancelled, then the destination is not in a
consistent state. In this case it is not safe to continue with the
migration.

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
2015-04-29 13:11:42 +02:00
Michael Chapman
1e106fee57 qemuDomainBlockJobAbort: use sync block job helpers
The !modern code path needs to call qemuBlockJobEventProcess directly.
the modern code path will call it via qemuBlockJobSyncWait.

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
2015-04-29 13:11:42 +02:00
Michael Chapman
1ec03c8772 qemuProcessStop: wake up pending sync block jobs
Other threads may be blocked in qemuBlockJobSyncWait. Ensure that
they're woken up when the domain is stopped.

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
2015-04-29 13:11:42 +02:00
Michael Chapman
89a5e25d05 qemuBlockJobSync*: introduce sync block job helpers
qemuBlockJobSyncBegin and qemuBlockJobSyncEnd delimit a region of code
where block job events are processed "synchronously".
qemuBlockJobSyncWait and qemuBlockJobSyncWaitWithTimeout wait for an
event generated by a block job.

The Wait* functions may be called multiple times while the synchronous
block job is active. Any pending block job event will be processed by
only when Wait* or End is called.  disk->blockJobStatus is reset by
these functions, so if it is needed a pointer to a
virConnectDomainEventBlockJobStatus variable should be passed as the
last argument. It is safe to pass NULL if you do not care about the
block job status.

All functions assume the VM object is locked. The Wait* functions will
unlock the object for as long as they are waiting. They will return -1
and report an error if the domain exits before an event is received.

Typical use is as follows:

  virQEMUDriverPtr driver;
  virDomainObjPtr vm; /* locked */
  virDomainDiskDefPtr disk;
  virConnectDomainEventBlockJobStatus status;

  qemuBlockJobSyncBegin(disk);

  ... start block job ...

  if (qemuBlockJobSyncWait(driver, vm, disk, &status) < 0) {
      /* domain died while waiting for event */
      ret = -1;
      goto error;
  }

  ... possibly start other block jobs
      or wait for further events ...

  qemuBlockJobSyncEnd(driver, vm, disk, NULL);

To perform other tasks periodically while waiting for an event:

  virQEMUDriverPtr driver;
  virDomainObjPtr vm; /* locked */
  virDomainDiskDefPtr disk;
  virConnectDomainEventBlockJobStatus status;
  unsigned long long timeout = 500 * 1000ull; /* milliseconds */

  qemuBlockJobSyncBegin(disk);

  ... start block job ...

  do {
      ... do other task ...

      if (qemuBlockJobSyncWaitWithTimeout(driver, vm, disk,
                                          timeout, &status) < 0) {
          /* domain died while waiting for event */
          ret = -1;
          goto error;
      }
  } while (status == -1);

  qemuBlockJobSyncEnd(driver, vm, disk, NULL);

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
2015-04-29 13:11:42 +02:00
Michael Chapman
206dbf3f0a qemuBlockJobEventProcess: move to new source file
We will want to use synchronous block jobs from qemu_migration as well,
so split this function out into a new source file.

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
2015-04-29 13:11:42 +02:00
Peter Krempa
a83b2e253f qemu: Validate available slot count for memory devices
While qemu would reject the configuration we can check whether it makes
sense to plug the device upfront.
2015-04-29 09:40:16 +02:00
Peter Krempa
6705d828fc qemu: command: Validate that memory devices slot ID is in range
slot id, if specified, has to be less than the slots count.
2015-04-29 09:40:16 +02:00
Peter Krempa
406944e476 qemu: conf: Reject memory device if it would exceed configured max size
If the added memory device would exceed the maximum memory size, reject
it.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1216046
2015-04-29 09:40:16 +02:00
Peter Krempa
ebe0bd5590 qemu: blockCopy: Allow reuse of raw image for shallow block copy
The documentation states that for shallow block copy the image has to
have the same guest visible content as backing file of the current
image if the file is being reused. This condition can be achieved also
with a raw file (or a qcow without a backing file) so remove the
condition that would disallow it.

(This patch additionally fixes crash described in
 https://bugzilla.redhat.com/show_bug.cgi?id=1215569 )
2015-04-29 09:32:53 +02:00
Maxim Nestratov
18f24c65d5 parallels: implement domainDetachDevice and domainDetachDeviceFlags
New functions utilize previosly added prlsdkDelDisk and prlsdkGetDiskIndex
Signed-off-by: Maxim Nestratov <mnestratov@parallels.com>
2015-04-28 19:00:53 +03:00
Maxim Nestratov
0d20195e53 parallels: add prlsdkDelDisk and prlsdkGetDiskIndex functions
Signed-off-by: Maxim Nestratov <mnestratov@parallels.com>
2015-04-28 18:58:48 +03:00
Martin Kletzander
922563e73a Fix building virnetserverclientmock with MinGW
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
2015-04-28 17:37:58 +02:00
Zhang Bo
e6bb622032 tests: free ChardevInfo correctly in qemumonitorjsontest
The free callback should be qemuMonitorChardevInfoFree rather
than just 'free' when virHashCreate'ing the chardevInfo hash.

==29959== 24 bytes in 2 blocks are definitely lost in loss record 19 of 53
==29959==    at 0x4C29F80: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==29959==    by 0xB95C679: strdup (in /lib64/libc-2.20.so)
==29959==    by 0x63C6546: virStrdup (virstring.c:709)
==29959==    by 0x4805ED: qemuMonitorJSONExtractChardevInfo (qemu_monitor_json.c:3429)
==29959==    by 0x4807A5: qemuMonitorJSONGetChardevInfo (qemu_monitor_json.c:3479)
==29959==    by 0x434AEC: testQemuMonitorJSONqemuMonitorJSONGetChardevInfo (qemumonitorjsontest.c:1824)
==29959==    by 0x436F2F: virtTestRun (testutils.c:211)
==29959==    by 0x436932: mymain (qemumonitorjsontest.c:2404)
==29959==    by 0x4382EA: virtTestMain (testutils.c:863)
==29959==    by 0x436B27: main (qemumonitorjsontest.c:2423)

Signed-off-by: Zhang Bo <oscar.zhangbo@huawei.com>
Signed-off-by: Zhou Yimin <zhouyimin@huawei.com>
2015-04-28 17:01:16 +02:00
Zhang Bo
6f5d29f40d qemu: make qemuMonitorChardevInfoFree non-static
It would be used in qemumonitorjsontest, thus we make it non-static.

Signed-off-by: Zhang Bo <oscar.zhangbo@huawei.com>
Signed-off-by: Zhou Yimin <zhouyimin@huawei.com>
2015-04-28 16:50:11 +02:00
Cole Robinson
56476f6a2d storage: fs: Ignore volumes that fail to open with EACCESS/EPERM
Trying to use qemu:///session to create a storage pool pointing at
/tmp will usually fail with something like:

$ virsh pool-start tmp
error: Failed to start pool tmp
error: cannot open volume '/tmp/systemd-private-c38cf0418d7a4734a66a8175996c384f-colord.service-kEyiTA': Permission denied

If any volume in an FS pool can't be opened by the daemon, the refresh
fails, and the pool can't be used.

This causes pain for virt-install/virt-manager though. Imaging a user
downloads a disk image to /tmp. virt-manager wants to import /tmp as
a storage pool, so we can detect what disk format it is, and set the
XML correctly. However this case will likely fail as explained above.

Change the logic here to skip volumes that fail to open. This could
conceivably cause user complaints along the lines of 'why doesn't
libvirt show $ROOT-OWNED-VOLUME-FOO', but figuring that currently
the pool won't even startup, I don't think there are any current
users that care about that case.

https://bugzilla.redhat.com/show_bug.cgi?id=1103308
2015-04-28 09:42:19 -04:00
Cole Robinson
65fc824666 storage: If driver startup state syncing fails, delete statefile
If you end up with a state file for a pool that no longer starts up
or refreshes correctly, the state file is never removed and adds
noise to the logs everytime libvirtd is started.

If the initial state syncing fails, delete the statefile.
2015-04-28 09:37:58 -04:00
Cole Robinson
af9dc75c1f storage: Break out storageDriverLoadPoolState
Will simplify a future patch
2015-04-28 09:37:57 -04:00
Cole Robinson
c180a3dcf7 storage: Don't leave stale state file if pool startup fails
After pool startup we call refreshPool(). If that fails, we leave
a stale pool state file hanging around.

Hit this trying to create a pool with qemu:///session containing
root owned files.
2015-04-28 09:37:57 -04:00
Cole Robinson
b29aff322f storage: Fix autostart dir for qemu:///session 2015-04-28 09:37:57 -04:00
John Ferlan
b515339fe7 qemu: Remove need for qemuMonitorIOThreadInfoFree
Replace with just VIR_FREE.
2015-04-28 06:33:49 -04:00
John Ferlan
69b16513a5 qemu: qemuProcessDetectIOThreadPIDs invert checks
If we received zero iothreads from the monitor, but were perhaps
expecting to receive something, then the code was skipping the check
to ensure what's in the monitor matches our expectations.  So invert
the checks to check that what we get back matches expectations and
then check there are zero iothreads returned.
2015-04-28 06:33:35 -04:00
John Ferlan
4c2ca5664a qemu: Remove need for qemuDomainParseIOThreadAlias
Rather than have a separate routine to parse the alias of an iothread
returned from qemu in order to get the iothread_id value, parse the alias
when returning and just return the iothread_id in qemuMonitorIOThreadInfoPtr

This set of patches removes the function, changes the "char *name" to
"unsigned int" and handles all the fallout.
2015-04-28 06:33:30 -04:00
John Ferlan
e505591e28 conf: Resolve some Coverity errors
Resolve some Coverity errors with IOThread changes

Signed-off-by: John Ferlan <jferlan@redhat.com>
2015-04-28 06:13:34 -04:00
Roman Bogorodskiy
fb9da19e90 conf: explicitly initialize 'cpumask' variable
Build with clang fails with:

  CC       conf/libvirt_conf_la-domain_conf.lo
  conf/domain_conf.c:13377:9: error: variable 'cpumask' is used
  uninitialized whenever 'if' condition is true
  [-Werror,-Wsometimes-uninitialized]
      if (!(tmp = virXMLPropString(node, "cpuset"))) {
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

and many other similar errors regarding the 'cpuset' variable.

Fix by explicitly initializing it with NULL.
2015-04-28 10:30:26 +04:00
Laine Stump
06313277f2 network: check newDef for used bridge names in addition to def
If someone has updated a network to change its bridge name, but the
network is still active (so that bridge name hasn't taken effect yet),
we still want to disallow another network from taking that new name.
2015-04-28 01:23:29 -04:00
Laine Stump
37b8bc6f12 network: check for bridge name conflict with existing devices
Since some people use the same naming convention as libvirt for bridge
devices they create outside the context of libvirt, it is much nicer
if we check for those devices when looking for a bridge device name to
auto-assign to a new network.
2015-04-28 01:21:41 -04:00
Laine Stump
a28d3e485f network: move auto-assign of bridge name from XML parser to net driver
We already check that any auto-assigned bridge device name for a
virtual network (e.g. "virbr1") doesn't conflict with the bridge name
for any existing libvirt network (via virNetworkSetBridgeName() in
conf/network_conf.c).

We also want to check that the name doesn't conflict with any bridge
device created on the host system outside the control of libvirt
(history: possibly due to the ploriferation of references to libvirt's
bridge devices in HOWTO documents all around the web, it is not
uncommon for an admin to manually create a bridge in their host's
system network config and name it "virbrX"). To add such a check to
virNetworkBridgeInUse() (which is called by virNetworkSetBridgeName())
we would have to call virNetDevExists() (from util/virnetdev.c); this
function calls ioctl(SIOCGIFFLAGS), which everyone on the mailing list
agreed should not be done from an XML parsing function in the conf
directory.

To remedy that problem, this patch removes virNetworkSetBridgeName()
from conf/network_conf.c and puts an identically functioning
networkBridgeNameValidate() in network/bridge_driver.c (because it's
reasonable for the bridge driver to call virNetDevExists(), although
we don't do that yet because I wanted this patch to have as close to 0
effect on function as possible).

There are a couple of inevitable changes though:

1) We no longer check the bridge name during
   virNetworkLoadConfig(). Close examination of the code shows that
   this wasn't necessary anyway - the only *correct* way to get XML
   into the config files is via networkDefine(), and networkDefine()
   will always call networkValidate(), which previously called
   virNetworkSetBridgeName() (and now calls
   networkBridgeNameValidate()). This means that the only way the
   bridge name can be unset during virNetworkLoadConfig() is if
   someone edited the config file on disk by hand (which we explicitly
   prohibit).

2) Just on the off chance that somebody *has* edited the file by hand,
   rather than crashing when they try to start their malformed
   network, a check for non-NULL bridge name has been added to
   networkStartNetworkVirtual().

   (For those wondering why I don't instead call
   networkValidateBridgeName() there to set a bridge name if one
   wasn't present - the problem is that during
   networkStartNetworkVirtual(), the lock for the network being
   started has already been acquired, but the lock for the network
   list itself *has not* (because we aren't adding/removing a
   network). But virNetworkBridgeInuse() iterates through *all*
   networks (including this one) and locks each network as it is
   checked for a duplicate entry; it is necessary to lock each network
   even before checking if it is the designated "skip" network because
   otherwise some other thread might acquire the list lock and delete
   the very entry we're examining. In the end, permitting a setting of
   the bridge name during network start would require that we lock the
   entire network list during any networkStartNetwork(), which
   eliminates a *lot* of parallelism that we've worked so hard to
   achieve (it can make a huge difference during libvirtd startup). So
   rather than try to adjust for someone playing against the rules, I
   choose to instead give them the error they deserve.)

3) virNetworkAllocateBridge() (now removed) would leak any "template"
   string set as the bridge name. Its replacement
   networkFindUnusedBridgeName() doesn't leak the template string - it
   is properly freed.
2015-04-28 01:20:11 -04:00
Laine Stump
dcbedfa672 test: Fix actual vs. expected in virtTestCompareFiles
Commit ca329299 added a utility function virtTestCompareFiles() to
eliminate repetitive code in several test programs. It unfortunately
calls virtTestDifference() with the arguments in the wrong order -
strcontent is the "actual" output gathered by the test rig, while
filecontent is the "expected", and virtTestDifference() wants expected
(filecontent) followed by actual (strcontent), but
virtTestCompareFiles() does the opposite, which can make the output a
bit confusing when there is a failure.
2015-04-27 15:12:23 -04:00
John Ferlan
d8082d2d44 qemu: Resolve Coverity DEADCODE
Coverity notes that the switch() used to check 'connected' values has
two DEADCODE paths (_DEFAULT & _LAST).  Since 'connected' is a boolean
it can only be one or the other (CONNECTED or DISCONNECTED), so it just
seems pointless to use a switch to get "all" values.  Convert to if-else
2015-04-27 14:55:35 -04:00
John Ferlan
1f7e811249 virsh: Add iothreadadd and iothreaddel commands
https://bugzilla.redhat.com/show_bug.cgi?id=1161617

Add command to allow adding and removing IOThreads from the domain including
the configuration and live domain.

$ virsh iothreadadd --help
  NAME
    iothreadadd - add an IOThread to the guest domain

  SYNOPSIS
    iothreadadd <domain> <id> [--config] [--live] [--current]

  DESCRIPTION
    Add an IOThread to the guest domain.

  OPTIONS
    [--domain] <string>  domain name, id or uuid
    [--id] <number>  iothread for the new IOThread
    --config         affect next boot
    --live           affect running domain
    --current        affect current domain

$ virsh iothreaddel --help
  NAME
    iothreaddel - delete an IOThread from the guest domain

  SYNOPSIS
    iothreaddel <domain> <id> [--config] [--live] [--current]

  DESCRIPTION
    Delete an IOThread from the guest domain.

  OPTIONS
    [--domain] <string>  domain name, id or uuid
    [--id] <number>  iothread_id for the IOThread to delete
    --config         affect next boot
    --live           affect running domain
    --current        affect current domain

Assuming a running $dom with multiple IOThreads assigned and that
that the $dom has disks assigned to IOThread 1 and IOThread 2:

$ virsh iothreadinfo $dom
 IOThread ID     CPU Affinity
 ---------------------------------------------------
  1               2
  2               3
  3               0-1

$ virsh iothreadadd $dom 1
error: invalid argument: an IOThread is already using iothread_id '1' in iothreadpids

$ virsh iothreadadd $dom 1 --config
error: invalid argument: an IOThread is already using iothread_id '1' in persistent iothreadids

$ virsh iothreadadd $dom 4
$ virsh iothreadinfo $dom
 IOThread ID     CPU Affinity
 ---------------------------------------------------
  1               2
  2               3
  3               0-1
  4               0-3

$ virsh iothreadinfo $dom --config
 IOThread ID     CPU Affinity
 ---------------------------------------------------
  1               2
  2               3
  3               0-1

$ virsh iothreadadd $dom 4 --config
$ virsh iothreadinfo $dom --config
 IOThread ID     CPU Affinity
  ---------------------------------------------------
    1               2
    2               3
    3               0-1
    4               0-3

Assuming the same original configuration

$ virsh iothreaddel $dom 1
error: invalid argument: cannot remove IOThread 1 since it is being used by disk 'vde'

$ virsh iothreaddel $dom 3

$ virsh iothreadinfo $dom
 IOThread ID     CPU Affinity
 ---------------------------------------------------
  1               2
  2               3

$ virsh iothreadinfo $dom --config
 IOThread ID     CPU Affinity
 ---------------------------------------------------
  1               2
  2               3
  3               0-1
2015-04-27 12:36:36 -04:00