libvirt: Releases
Description: libvirt, virtualization, virtualization API

# Releases

This is the list of official releases for libvirt, along with an overview of the changes introduced by each of them.

For a more fine-grained view, use the git log.

### v4.2.0 (2018-04-01)

- New features
  - Support building with Python 3
    Python is required to build libvirt, and up until now only Python 2 could be used as an interpreter. All scripts used during build have now been made compatible with Python 3, which means both major releases of the language are fully supported.
  - qemu: Provide ccw address support for graphics and input devices
    Support the virtio-gpu-ccw device as a video device and virtio-{keyboard, mouse, tablet}-ccw devices as input devices on S390.
- Improvements
  - qemu: Add logging of guest crash information on S390
    On S390, when the guest crashes and QEMU exposes the guest crash information, log the relevant data to the domain log file.
  - qemu: use arp table of host to get the IP address of guests
    Find IP address of a VM by arp table on hosts. If someone customizing IP address inside VM, it will be helpful.
  - Xen: Remove hard-coded scheduler weight
    The libxl driver was accidentally hard-coding the per-domain scheduler weight to 1000, silently ignoring any user-provided `<shares>` in `<cputune>`. The driver now honors `<shares>`, and defers setting a default value to Xen. Note that the Xen default is 256, so any domains started after this improvement will have one fourth the shares of previously started domains. If all domains must have equal CPU shares, administrators must manually set the weight of previously started domains to 256, or restart them.
- Bug fixes

### v4.1.0 (2018-03-05)

- New features
  - Added support for CAT (Cache allocation Technology)
    Domain vCPU threads can now have allocated some parts of host cache using the `cachetune` element in `cputune`.
  - Allow opening secondary drivers
    Up until now it was possible to connect to only hypervisor drivers (e.g. qemu:///system, lxc:///, vbox:///system, and so on). The internal drivers (like network driver, node device driver, etc.) were hidden from users and users could use them only indirectly. Starting with this release new connection URIs are accepted. For instance network:///system, storage:///system and so on.
  - virtlogd, virtlockd: Add support for admin protocol
    These two daemons now support admin protocol through which some admin info can be gathered or some configuration tweaked on the fly.
- Improvements
  - virsh: Enhance bash completion
    Implement more bash completions so that basic libvirt objects can be auto-completed (e.g. networks, interfaces, NWFilters, and so on).
  - qemu: Use VIR_ERR_DEVICE_MISSING for various hotplug/detach messages
  - qemu: Allow showing the dump progress for memory only dump
    Alter the QEMU dump-guest-memory command processing to check for and allow asynchronous completion which then allows for the virsh dump --memory-only --verbose command to display percent completion data.
  - conf: add support for setting Chassis SMBIOS data fields
  - libxl: add support for setting clock offset and adjustment
  - Make port allocator global
    Up until now each driver had their own port allocator module. This meant that info on port usage was not shared. Starting with this release, the port allocator module is made global and therefore drivers allocate ports from global pool.
  - Fixed some compiler warnings that appear with GCC 8
- Bug fixes
  - qemu: Check for unsafe migration more thoroughly
    If a domain disk is stored on local filesystem (e.g. ext4) but is not being migrated it is very likely that domain is not able to run on destination. Regardless of share/cache mode.
  - qemu: Fix updating device with boot order
    Starting with 3.7.0 release updating any device with boot order would fail with 'boot order X is already used by another device' while in fact it was the very same device.
  - virlog: determine the hostname on startup CVE-2018-6764
    At later point it might not be possible or even safe to use getaddrinfo(). It can in turn result in a load of NSS module which can even be loaded from unsage guest filesystem and thus escape the confinment of its container.
  - qemu: Rework vCPU statistics fetching
    Fetching vCPU statistics was very expensive because it lead to waking up vCPU threads in QEMU and thus it degraded performance. The code was reworked so that fetching statistics does not wake up halted vCPUs.
  - qemu: unlink memory backing file on domain shutdown
    Depending on the filesystem where domain memory is stored, some files might have been left behind. This is not a problem on hugetlbfs, but it is a problem on regular filesystems like ext4.
  - qemu: Fix shutting down domains in parallel
    If multiple domains were being shut down in parallel, libvirtd might have deadlocked.
  - nodedev: Update PCI mdev capabilities dynamically
    PCI devices may have other nested capabilities, like SRIOV and mdev which depend on the device being plugged into the native vendor driver. However, in case such a device is directly assigned to a guest using VFIO driver, the device will naturally lose these capabilities and libvirt needs to reflect that.

### v4.0.0 (2018-01-19)

- New features
  - tools: Provide bash completion support
    Both `virsh` and `virt-admin` now implement basic bash completion support.
  - qemu: Refresh capabilities on host microcode update
    A microcode update can cause the CPUID bits to change; therefore, the capabilities cache should be rebuilt when such an update is detected on the host.
  - lxc: Set hostname based on container name
- Improvements
  - CPU frequency reporting improvements
    The CPU frequency will now be reported by `virsh nodeinfo` and other tools for s390 hosts; at the same time; CPU frequency has been disabled on aarch64 hosts because there's no way to detect it reliably.
  - libxl: Mark domain0 as persistent
  - Xen: Add support for multiple IP addresses on interface devices
  - qemu: Add support for hot unplugging redirdev device
- Bug fixes
  - qemu: Enforce vCPU hotplug granularity constraints
    QEMU 2.7 and newer don't allow guests to start unless the initial vCPUs count is a multiple of the vCPU hotplug granularity, so validate it and report an error if needed.

### v3.10.0 (2017-12-04)

- New features
  - conf: Support defining distances between virtual NUMA cells
    A NUMA hardware architecture supports the notion of distances between NUMA cells. This can now be specified using the `<distances>` element within the NUMA cell configuration. Drivers which support this include Xen and QEMU.
  - Xen: Support defining vNUMA topology
    Xen now supports defining a virtual NUMA topology for VMs, including specifying distances between NUMA cells.
  - qemu: Add the ability to configure HPT resizing for pSeries guests
    The user can now decide whether HPT (Hash Page Table) resizing should be enabled, disabled or required instead of leaving it up to hypervisor defaults and negotiation between the guest and the host.
  - qemu: Add vmcoreinfo feature
    Starting with QEMU 2.11, the guest can save kernel debug details when this feature is enabled and the kernel supports it. It is useful to process kernel dump with KASLR enabled, and also provides various kernel details to crash tools.
  - conf: Move the auth and encryption definitions to disk source
    Allow parsing and formatting of the `auth` and `encryption` sub-elements to be a child of the `source` element. This will allow adding an `auth` sub-element to a `backingStore` or `mirror` elements as a means to track specific authentication and/or encryption needs.
- Improvements
  - vbox: Add VirtualBox 5.2 support
  - vbox: Add support for configuring storage controllers
    The VirtualBox driver now supports the `<controller>` element in the domain XML for configuring storage controllers in VBOX VMs. Additionally, libvirt's domain XML schema was updated to allow optional `model` attribute for `<controller type='ide'>` which is used by the VBOX driver to set the IDE controller model to be one of 'piix4', 'piix4' (default), or 'ich6'. Finally, with this change `dumpxml` generates `<controller>` elements that correspond to current VBOX VM storage controller configuration.
  - vbox: Add support for attaching empty removable disks
    The VirutalBox driver now supports adding CD-ROM and floppy disk devices that do not have the disk source specified. Previously such devices were silently ignored.
  - vbox: Add support for attaching SAS storage controllers
    In VirtualBox, SCSI and SAS are distinct controller types whereas libvirt does not make such distinction. Therefore, the VBOX driver was updated to allow attaching SAS controllers via `<controller type='scsi' model='lsisas1068'>` element. If there are both SCSI and SAS controllers present in the VBOX VM, the domain XML can associate the disk device using the `<address>` element with the `controller` attribute, and optionally, set the port via `unit` attribute.
  - qemu: Generate predictable paths for qemu memory backends
    In some cases management applications need to know paths passed to memory-backend-file objects upfront. Libvirt now generates predictable paths so applications can prepare the files if they need to do so.
  - Shareable disks work properly with recent qemu
    Recent qemu versions added image locking to avoid potential corruption of disk images. This broke shareable disks with libvirt since the feature was turned on by default in qemu. Libvirt now enables sharing of those disks in qemu so that the image locking is not applied in that case. Additionally libvirt now checks that shareable disks have supported format (raw) to avoid metadata corruption.
  - Improve serial console behavior on non-x86 architectures
    ppc64, aarch64 and s390x guests were treating the <serial> and <console> elements differently from x86, in some cases presenting misleading information to the user. The behavior is now consistent across all architectures and the information reported is always accurate.
- Bug fixes
  - vbox: Do not ignore failures to attach disk devices when defining
    The `define` now fails and reports an error if any of the `controller` or `disk` devices specified in the domain XML fail to attach to the VirtualBox VM.
  - vbox: Fix dumpxml to always output disk devices
    The VirtualBox driver was ignoring any disk devices in `dumpxml` output if there was a SAS storage controller attached to the VM.
  - vbox: Fix dumpxml to always generate valid domain XML
    When a VirtualBox VM has multiple disks attached, each to a different storage controller that uses 'sd' prefix for block device names e.g. one disk attached to SATA and one to SCSI controller, it no longer generates XML where both would have 'sda' device name assigned. Instead it properly assigns 'sda' and 'sdb' to those disks in the order of appearance.
  - Securely pass iSCSI authentication data
    Rather than supplying the authentication data as part of the iSCSI URL for a disk or host device, utilize the encrypted secret object to securely pass the authentication data.

### v3.9.0 (2017-11-02)

- New features
  - Add capability to allow hot (un)plug of a domain watchdog device
  - Allow users to set device aliases
    Users can set aliases to domain devices and thus identify them easily.
  - qemu: Support multiqueue for virtio-blk
    Multiqueue support for `virtio-blk` has been available in QEMU ever since 2.7.0, and now libvirt guests can enable it.
  - Add virDomainSetLifecycleAction API
    Provided a new API to allow dynamic guest lifecycle control for guest reactions to poweroff, restart, or crash type events related to the domain XML `on_poweroff`, `on_reboot`, and `on_crash` elements. The `virsh set-lifecycle-action` command was created to control the actions.
  - qemu: Allow cold(un)plugging and hot(un)plugging input devices
  - net: Implement QoS for vhostuser
- Improvements
  - Allow a logical volume to be create using LUKS
    A logical volume may be created using an `encryption` element using "luks" format. This does require a previously created `secret` to store the passphrase used to encrypt the volume Adding the volume to a domain can then either provide the secret or allow the consumer in the guest to provide the passphrase in order to decrypt the volume.
  - net: Ignore auto-generated MAC address when detaching an interface
    If the MAC address has not been specified by the user, libvirt will try and fill in the gaps by generating one; however, for some error paths that led to some confusing error messages, so when an auto-generated MAC address is specified the error message will not include the auto-generated MAC.
  - net: Enable MAC address lookup for virDomainInterfaceStats
  - apparmor: Several improvements
    Changes include permitting access to data about USB devices and `dnsmasq` instances, allowing spaces in guest names and many more.
  - cpu: Use CPU information obtained from QEMU when possible
    Recent QEMU versions can expose information about which CPU models are available and usable on the host; libvirt will now make use of such information whenever possible.
  - hyperv: Various improvements
    The error reported when clients can't connect to Hyper-V has been made more descriptive, and memory limits for guests are now mapped to more appropriate libvirt equivalents.
  - qemu: Report QEMU error on failed migration
    Instead of reporting a generic error, ask QEMU for a more detailed and thus hopefully more helpful one.
  - vbox: Implement autoport for RDP
    libvirt will now obtain the (dynamically allocated) RDP port number from VirtualBox itself, avoiding conflicts between multiple guests wanting to use RDP at the same time.
  - qemu: Allow rotation of small logs
    On a host where numerous unique instances are executed per day, it's quite possible that, even though each of the single log files are fairly small, collectively the quantity and volume may add tens of thousands of log files to the `/var/log/libvirt/qemu/` directory. Removing the constraints that log have to be bigger than 100 KiB before they can be rotated solves the issue.
- Bug fixes
  - Fix swapped interface statistics and QoS
    Due to internal implementation, reported statistics for some types of interfaces were swapped (RX appeared in TX and vice versa). Similarly, QoS was set in reversed way.
  - Properly resize local LUKS encrypted volume
    Resizing of a local LUKS encrypted volume will now use qemu-img to resize the volume. This will require configuring a secret for the LUKS encrypted volume.
  - qemu: Reserve PCI addresses for implicit i440fx devices
    Failing to do so causes the addresses to be considered usable by libvirt, which means they could be assigned to more than one device resulting in the guest failing to start.
  - spec: Restart libvirtd only at the end of the upgrade process
    Use `%posttrans` to make sure `libvirtd` is not restarted before all other components, such as the library itself and storage / hypervisor drivers, have already been upgraded.
- Security
  - qemu: Ensure TLS clients always verify the server certificate
    While it's reasonable to turn off client certificate validation, as setting it up can be non-trivial, clients should always verify the server certificate to avoid MITM attacks. However, libvirt was using the same knob to control both checks, leading to CVE-2017-1000256 / LSN-2017-0002.

### v3.8.0 (2017-10-04)

- New features
  - qemu: Added support for cold-(un)plug of watchdog devices
  - qemu: Added support for setting IP address os usernet interfaces
  - qemu: Added support for Veritas Hyperscale (VxHS) block devices
  - storage: Added new events for pool-build and pool-delete
- Improvements
  - qemu: Set DAC permissions properly for spice rendernode
    When a `rendernode` path is set for SPICE GL on `qemu:///system`, we now correctly set DAC permissions on the device at VM startup. This is the last remaining hurdle to let SPICE GL work for `qemu:///system` without any external host changes.
  - nodedev: Add switchdev offload query to NIC capabilities
    Allow querying the NIC interface capabilities for the availability of switchdev offloading (also known as kernel-forward-plane-offload).
  - New CPU models for AMD and Intel
    AMD EPYC and Intel Skylake-Server CPU models were added together with their features
  - Improve long waiting when saving a domain
    While waiting for a write to disk to be finished, e.g. during save, even simple operations like `virsh list` would be blocking due to domain lock. This is now resolved by unlocking the domain in places where it is not needed.
- Bug fixes
  - Proper units are now used in virsh manpage for dom(mem)stats
    Previously the documentation used multiples of 1000, but now it is fixed to use multiples of 1024.
  - qemu: Fix error reporting when disk attachment fails
    There was a possibility for the actual error to be overridden or cleared during the rollback.
  - qemu: Fix assignment of graphics ports after daemon restart
    This could be seen with newer kernels that have bug regarding SO_REUSEADDR. After libvirtd was restarted it could assign already used address to new guests which would make them fail to start. This is fixed by marking used ports unavailable when reconnecting to running QEMU domains.
  - Fix message decoding which was causing a very strange bug
    When parsing an RPC message with file descriptors was interrupted and had to restart, the offset of the payload was calculated badly causing strange issues like not being able to find a domain that was not requested.

### v3.7.0 (2017-09-04)

- New features
  - qemu: Add managedsave-edit commands
    Using managedsave-dumpxml, managedsave-define and managedsave-edit commands, now we can dump and edit the XML configuration of domain which has managedsave image.
  - qemu: Add migrate-getmaxdowntime command
    Currently, the maximum tolerable downtime for a domain being migrated is write-only from libvirt, via migrate-setmaxdowntime. This implements a complementary migrate-getmaxdowntime command
  - bhyve: Support autoport for VNC ports
    It's no longer necessary to explicitly specify VNC port for the bhyve guests. With the autoport feature it will be allocated automatically. Please refer to the bhyve driver documentation for examples.
  - qemu: Added support for setting heads of virtio GPU
  - qemu: Added support to configure reconnect timeout for chardev devices
    When you have a TCP or UNIX chardev device and it's connected somewhere you can configure reconnect timeout if the connection is closed.
- Improvements
  - qemu: Report a clear error when dropping a VM during startup
    "Failed to load config for domain 'DOMNAME'" is now reported if a VM config can't be parsed for some reason, and thus provides a clear indication for users (and devs).
  - apparmor: Update for QEMU 2.10 compatibility
    Starting with QEMU 2.10, disk images and NVRAM files get automatically locked to prevent them from being corrupted; however, file locking needs to be explicitly allowed through `virt-aa-helper` or AppArmor will reject the requests and the guest will not be able to run.
  - virsh: List Unix sockets in 'domdisplay' output
    VNC and SPICE graphics can use Unix sockets instead of TCP/IP sockets as connection endpoints, but such a configuration was not handled correctly by `virsh domdisplay`, causing the respective endpoints to be missing from the output.
  - qemu: Don't check whether offline migration is safe
    Since offline migration only copies the guest definition to the destination host, data corruption is not a concern and the operation can always be performed safely.
  - virt-host-validate: Fix IOMMU detection on ppc64
- Bug fixes
  - qemu: Better support for international domain names (with wide characters)
    There were some issues with multi-byte domains getting lost on daemon restart due to truncation, so the code now handles multi-byte names a bit better.
  - qemu: Support long domain names with namespaces
    Domains with extremely long names would fail to start due to temporary namespace paths being created with the whole name. The path is now generated with shortened name instead.
  - qemu: Tolerate missing emulator binary during libvirtd restart
    For some time libvirt required qemu capabilities being present when parsing VM configs during startup. As a side effect VM configs would fail to parse and thus vanish, if the emulator binary would be uninstalled or broken. Libvirt now tolerates when capabilities are missing during startup.
  - qemu: Prevent pSeries guests from disappearing in some situations
    pSeries guest would disappear if any of the host devices they were configured to use was not available during libvirtd startup, which could easily happen for SR-IOV Virtual Functions. This scenario is now handled correctly.
  - qemu: Honor <on_reboot/> setting
    The setting was accepted by the parser, but not actually implemented.
  - Fix --verbose option for all daemons
    Since v3.0.0, the option had been ignored by all libvirt daemons (`libvirtd`, `virtlogd` and `virtlockd`); it's now working as intended once again.

### v3.6.0 (2017-08-02)

- New features
  - hyperv: Implement virDomainSetMemory and virDomainSendKey APIs
  - qemu: Support multiple PHBs for pSeries guests
    pSeries guests can now have multiple PHBs (PCI Host Bridges), which show up as separate PCI domains in the guest. To create additional PHBs, simply add PCI controllers with model `pci-root` to the guest configuration.
  - qemu: Isolate hostdevs on pSeries guests
    To enable better error reporting and recovery, unrelated hostdevs will now be automatically isolated on pSeries guests by placing them on separate PHBs (PCI Host Bridges).
- Improvements
  - qemu: platform serial devices can now use chardev features
    QEMU VMs that depend on platform serial devices can now use QEMU's `-chardev` option, which enables access to advanced features like log file configuration. This applies to the default serial devices for arm, aarch64, and some ppc configurations.
  - Require use of GCC 4.4 or Clang compilers
    We only ever test libvirt with GCC or Clang (which provides a GCC compatible compilation environment). Between them, these compilers cover every supported operating system platform, including Windows.
  - qemu: shared disks with directsync cache should be safe for migration
    At present shared disks can be migrated with either readonly or `cache=none`. But `cache=directsync` should be safe for migration, because both `cache=directsync` and `cache=none` don't use the host page cache, and `cache=direct` write through qemu block layer cache.
  - Handle hotplug change on VLAN configuration using OVS
    Libvirt was taught to handle VLAN change for running OVS interface.
- Bug fixes
  - qemu: Use vCPU 'node-id' property and pass it back to qemu
    vCPU properties gathered from query-hotpluggable-cpus need to be passed back to QEMU. As QEMU did not use the node-id property until now and libvirt forgot to pass it back properly (it was parsed but not passed around) we did not honor this.
  - Miscellaneous stream fixes
    After introducing sparse stream features there were still some known bugs left. Those are fixed in this release.
  - qemu: Miscellaneous domain NS fixes
    Libvirt starts qemu domains in separate Linux namespaces for a while now. However, there were still some bugs lingering. For instance libvirt did not know how to handle file based bind mounts.
  - Various CPU driver improvements
    There were some minor bugs when using 'host-model' CPU.

### v3.5.0 (2017-07-04)

- New features
  - qemu: Add support for loadparm for a boot device
    Add an optional boot parameter 'loadparm' for a boot device. Loadparm is an 8 byte parameter that, when present, is queried by S390 guests via sclp or diag 308. Linux guests on S390 use it to select a boot entry.
  - Support controlling how video devices are exposed to the bhyve guests
    The `vgaconf` attribute was added to `video`'s `driver` element. Possible values are: `on`, `off`, and `io`. It controlls the way how bhyve exposes video devices to its guests; various guest OSes might require different settings to boot properly.
  - qemu: Add support for live updates of coalesce settings
    Users can now use `virsh update-device` to change the coalesce settings of an interfaces while the domain is running.
  - qemu: Allow VirtIO devices to use vIOMMU
    It is now possible to turn on IOTBL for the vIOMMU and have VirtIO devices use it, provided they have been configured appropriately.
- Improvements
  - qemu: block copy job can be used with persistent domains
    Until now it was not possible to use block copy with persistent VMs. In use cases where it's not required to recover the job after VM shutdown, it's possible to specify VIR_DOMAIN_BLOCK_COPY_TRANSIENT_JOB flag to start the copy job.
  - JSON pseudo-protocol backing store parser supports new format of qemu 2.9
    QEMU 2.9 modified a few structures corresponding to the JSON format of specifying a backing store for a disk image. Libvirt now implements the new format.
  - Capabilities now include info about host's CAT settings
    Various information about resource control from the host is gathered and presented in capabilities if available.
  - apparmor: Several improvements
    Allow access to Ceph config, EFI firmware on both x86_64 and aarch64, device tree on ppc64 and more.
  - qemu: Support host-model on POWER9 machines
- Bug fixes
  - qemu: snapshot: retrieve image metadata from user provided files
    Disk images of an external snapshot created with VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT flag specified would not be scanned for metadata after recent changes. The metadata is necessary to allow keeping relative paths between images when doing a block-commit.
  - Parse decimal numbers in a locale-independent way
    Some locales, such as `de_DE` and `pt_BR`, use comma rather than dot to separate the integer part from the fractional part of a decimal number; however, several data sources such as the kernel use a locale-independent representation and need to be treated accordingly.
  - Support compilation with newer compiler and libc versions
    Several fixes have been included to make compilation with Clang 4.0.0, GCC 7.1 and glibc >= 2.25.90 possible.
  - qemu: Query name for vhost-user interfaces at runtime
    This makes it possible to use `virsh` subcommands such as `domiflist` and `domifstat` on vhost-user interfaces.
  - qemu: Set MTU for hotplugged interfaces correctly
    When hotplugging a network interface, the MTU was only set on the guest side. Set it on the host side as well.
  - qemu: Forbid updating MTU for interfaces of running guests
    The MTU setting can't be modified while the guest is running, so any attempt to alter it at runtime will now result in an error rather than being silently ignored.
  - qemu: Fix specifying QXL heads with older QEMU releases
    Specifying the number of QXL heads was not working correctly for QEMU releases older than 1.6.
  - qemu: Fix migration to older libvirt/QEMU versions
    When the guest is started, libvirt updates the CPU definition to reflect the actual CPU features to enforce ABI. We need to send original and updated CPU definition in order to support migration to older libvirt/QEMU versions. Only the updated CPU definition was sent to destination.

### v3.4.0 (2017-06-02)

- New features
  - Improved streams to efficiently transfer sparseness
    New extension to virStream was implemented so that virStorageVolDownload and virStorageVolUpload can preserve file sparseness.
  - I/O APIC type can be specified for QEMU/KVM domains
    The `ioapic` tag was added to domain `features`, so the type of the I/O APIC can now be specified (e.g. putting it in userspace for KVM domains).
  - The reason for VM shutdown is reported, if known
    QEMU 2.10 will be able to report the reason for shutting down (whether that was caused by the guest or not), and libvirt is prepared for that and reports that information in its shutdown event as well, if it is known.
- Improvements
  - Repository now has new README.md file
    The new file uses markdown syntax, so it looks better on github and possibly other web pages, but it has also more useful information. The old README is now symlink to the new file.
  - qemu: Use GICv2 by default for aarch64/virt TCG guests
    The emulated GICv3 has some limitations that make it unusable as a default; use GICv2 until they're sorted out. This change makes it once again possible to run aarch64/virt guests on a x86_64 host without having to tweak their configuration.
  - Additional capabilities for the node_device module
    Introduce two new capabilities to the node_device module. The first is for CCW devices, most common on the S390 architecture. The second is for fibre channel-backed SCSI devices and exposes the fc_remote_port sub-capability to SCSI target devices.
  - Node devices now report Mediated device capabilities
    Endpoint devices support new `mdev` capability and their parents now report the supported types in new `mdev_types` capability.
  - Capabilities now report information about host caches
    If supported in the kernel, host capabilities will now list L3 caches. The code for other levels was added as well, but only L3 caches are reported currently.
  - POWER9 CPU model was added
    It is now properly reported in host capabilities.
  - libxl: NUMA sibling distances are now reported in host capabilities
  - VMDK version 3 files are now properly detected
  - Interrupt remapping and Extended interrupt mode for IOMMU devices
    These two new features can now be controlled with new `<driver intremap='on/off' eim='on/off'/>` tag for `iommu` devices.
  - Graphics in libxl domains now have default addresses
    Even though there were default addresses before this change, they were not saved in the XML. It is now possible to see and control the listen addresses properly.
  - Default USB controllers are now added for devices in libxl domains
    Even though they were added automatically when USB device was attached, they could've been missing in some other cases. The logic is now fixed so there are always USB controllers, even if there was none of them in the specified XML.
  - Limits for RPC messages were increased
    Hitting the RPC limits we have is easier every day, so they were increased once again and some guessing logic was improved as well. It is now possible to get more stats than ever using the `virConnectGetAllDomainStats()` call and push through even bigger requests and replies for all APIs.
- Bug fixes
  - qemu: Create memory_backing_dir on startup
    Libvirt's policy is that directories are created on startup if they don't exist. We've missed this one.
  - PCIe 4.0 cards now report proper link speeds
    It could happen that the link speed for PCIe devices was not properly reported or the nodedev-dumpxml just failed. That was due to mistake in the field width, but should now work properly.
  - qemu: Do not report errors on shutdown
    For some users, in some rare cases, it could happen that there was an error message "internal error: End of file from qemu monitor" in the logs even though no problem happened. The detection of these false positives was improved and such errors should not show any more.
  - User-specified UNIX socket paths for virtio channels should not be reset
    It could happen, in some cases, that libvirt would mistake a user-specified path for its own generated one and thus remove it from the XML. The detection of such addresses was improved now.
  - Fix address reservation during RNG hot-plug
    When error occurred in a specific point in time during the hot-plug of an RNG device, it could happen that an address was released even though another device was already using it, making it possible to hot-plug another device with that address, effectively having duplicated addresses in the XML.

### v3.3.0 (2017-05-05)

- New features
  - net: Add support for coalesce settings
    Enabling data batching through these settings can improve network performance for guests.
  - qemu: Add support for guest CPU cache specification
    This features allows fine-grained control of the cache behavior of the guest CPU.
  - qemu: Add support for the qemu-xhci USB controller
- Improvements
  - hyperv: Support Hyper-V 2012 and newer
    Starting with Hyper-V 2012 the API has changed causing the existing driver to be unable to send and process requests properly. This has been resolved by adding abstractions to handle the differences and ease handling such breaks if they happen in the future.
  - libxl: Add support for nested HVM domains
    Xen has supported nested HVM domains since version 4.4. The libvirt libxl driver now supports nested HVM domains by specifying the host-passthrough CPU mode when defining a domain.
  - qemu: Implement ACPI support for aarch64 guests
    Up until this point, ACPI support was only advertised for x86_64 guests and disabling it for aarch64 guests was not possible at all.
  - vz: Add support for changing the number of vCPUs
  - qemu: Automatically choose the best USB controller for guests
    The recently introduced qemu-xhci USB controller is the best choice for both ppc64 and aarch64 guests, so use it by default on those architectures if available.
  - daemon: Increase default task limit for libvirtd
    The default number of tasks for the pids cgroup controller is 512, which libvirtd can quickly bump into when starting lots of guests. Raise the limit to a more reasonable 32768.
  - docs: Include man pages describing key code names and values
  - virsh: Report initialization errors
    Sometimes virsh might be unable to start: when that happens, report useful diagnostics instead of failing silently.
- Bug fixes
  - nss: Don't require a network restart for libvirt_guest
    Previously, the libvirt_guest NSS module would only work properly after the corresponding network had been restarted; now newly started guests will be reported correctly right away.
  - storage: Remove unavailable transient pools after restart
    Solve an issue where transient storage pools would be stuck in an unmanageable state if the source disappeared and libvirtd was subsequently restarted.
  - storage: Fix capacity value for LUKS encrypted volumes
    The 'capacity' value (e.g. guest logical size) for a LUKS volume is smaller than the 'physical' value of the file in the file system, so we need to account for that.
  - qemu: Fix regression when hyperv/vendor_id feature is used
    Guests using the feature would not be started at all; it is now possible to start them as expected.
  - qemu: Do not crash on USB address with no port and invalid bus
  - crypto: Always pad data before encrypting it
    If this step is not performed, when the data length matches the chunk size the decryption routines will misinterpret the last byte of data as the padding length and fail to decode it correctly.

### v3.2.0 (2017-04-02)

- New features
  - The virt-host-validate tool now supports bhyve hypervisor
  - Introduce NVDIMM memory model
    NVDIMM is new type of memory introduced into QEMU 2.6. The idea is that we have a non-volatile memory module that keeps the data persistent across domain reboots and offers much faster data accesses. However, due to a bug in QEMU, this feature is not enabled for QEMUs older than 2.9.0.
  - qemu: Introduce support for generic PCIe Root Ports
    For new controllers, a generic device (pcie-root-port) will be used by default instead of the Intel-specific device (ioh3420), provided the QEMU binary supports it.
  - qemu: Add support for checking guest CPU ABI compatibility
    When migrating a domain to a different host, restoring a domain from a file or reverting a snapshot libvirt will make sure the guest CPU QEMU presents to the guest OS exactly matches the one provided on the source host (or before the domain's state was saved). This enhanced check may also be requested when starting a new domain to ensure the virtual CPU exactly matches the one specified in the XML.
  - qemu: Add support to migrate using TLS
    Add the ability to migrate QEMU guests using TLS via a new flag VIR_MIGRATE_TLS or virsh migrate '--tls' option. Requires using at least QEMU 2.9.0 in order to work properly.
  - qemu: add mediated devices framework support
    Recent kernel version introduced new mediated device framework, so provide an initial support of this framework for libvirt, mainly by introducing a new host device type in the XML.
  - qemu: Add support for setting TSC frequency
    Setting TSC frequency is required to enable migration for domains with 'invtsc' CPU feature turned on.
  - Add support for block device threshold event
    When using thin provisioning, management tools need to resize the disk in certain cases. To avoid having them to poll disk usage this version introduces an event which will be fired when a given offset of the storage is written by the hypervisor. Together with the API it allows registering thresholds for given storage backing volumes and this event will then notify management if the threshold is exceeded. Currently only the qemu driver supports this.
  - bhyve: Add support for UEFI boot ROM, VNC, and USB tablet
    The bhyve driver now supports booting using the UEFI boot ROM, so non-FreeBSD guests that support UEFI could be booted without using an external boot loader like grub-bhyve. Video is also supported now, allowing to connect to guests via VNC and use an USB tablet as an input device. Please refer to the driver page for domain XML examples.
- Improvements
  - qemu: Detect host CPU model by asking QEMU on x86_64
    Previously, libvirt detected the host CPU model using CPUID instruction, which caused libvirt to detect a lot of CPU features that are not supported by QEMU/KVM. Asking QEMU makes sure we don't start it with unsupported features.
  - perf: Add more perf statistics
    Add support to get the count of cpu clock time, task clock time, page faults, context switches, cpu migrations, minor page faults, major page faults, alignment faults, emulation faults by applications running on the platform.
  - Write hyperv crash information into vm log
    qemu's implementation of the hyperv panic notifier now reports information about the crash from the guest os. Starting with this version, libvirt logs the information to the vm log file for possible debugging.
- Bug fixes
  - QEMU: Use adaptive timeout for connecting to monitor
    When starting qemu, libvirt waits for qemu to create the monitor socket which libvirt connects to. Historically, there was sharp 30 second timeout after which the qemu process was killed. This approach is suboptimal as in some scenarios with huge amounts of guest RAM it can take a minute or more for kernel to allocate and zero out pages for qemu. The timeout is now flexible and computed by libvirt at domain startup.
  - Overwrite (clear) 2 KB instead of just 512 bytes when initializing logical device
  - Describe the logical backend requirements better for pool-create-as

### v3.1.0 (2017-03-03)

- New features
  - storage: Add Virtuozzo storage backend storage pool
    Add new storage backend to support pool and volume management within the Virtuozzo Storage environment. Virtuozzo Storage is a highly available distributed software defined storage with built-in replication and disaster recovery.
  - qemu: Add support for memory backing with file source
    Add support in numa topology for file source inside memory backing (hugepages are not needed) Three new elements <source/>,<access/> and <allocation/> were added to <memoryBacking/> element. Also new configuration parameter `memory_backing_dir` was added to qemu.conf.
  - network: make openvswitch call timeout configurable
    Adding the ability to specify the timeout value in seconds for openvswitch calls in the libvirtd configuration file.
  - bhyve: add e1000 NIC support
    Add support for e1000 NIC. Previously, the only available option was `virtio-net`.
  - libxl: add tunneled migration support
    Add tunneled migration to libxl driver, which is always capable of strong encryption and doesn't require any extra network connection other than what's required for remote access of libvirtd.
  - qemu: add rendernode argument
    Add a new attribute 'rendernode' to <gl> spice element.
  - nodedev: add drm capability
    Add a new 'drm' capability for Direct Rendering Manager (DRM) devices, providing device type information.
  - Add API for individual/specific vCPU hotplug
    The new API allows selecting specific vCPUs to be added/removed from the VM. The existing APIs allowed only adding/removing from the end which did not play well with NUMA.
- Improvements
  - virsh: pool-list: allow both --uuid and --name in one command
    Adjust the virsh-pool command to support the --uuid and/or --name options in order to print just the --name and/or --uuid of pools.
  - Introduce MTU to domain <interface/> and <network>
    Allow setting MTU size for some types of domain interface and network.
  - libxl: improve support for <timer> configurations
    Add support for multiple timers. Extend the tsc timer to support the emulate mode. Improve conversion of timer XML to/from xl.cfg.
  - storage: modularize the storage driver
    Split up the storage driver backends into loadable modules so that binary distributions don't have to compromise on shipping the storage driver with all backends which may pull in too many dependencies.
- Bug fixes
  - nodedev: Fabric name must not be required for fc_host capability
    fabric_name is one of many fc_host attributes in Linux that is optional and left to the low-level driver to decide if it is implemented. For example the zfcp device driver does not provide a fabric name for an fcp host. The requirement for the existence of a fabric name has been removed by making it optional.
  - bhyve: change address allocation schema for SATA disks
    Previously, the bhyve driver assigned PCI addresses to SATA disks directly rather than assigning that to a controller and using SATA addresses for disks. It was implemented this way because bhyve has no notion of an explicit SATA controller. However, as this doesn't match libvirt's understanding of disk addresses, the bhyve driver was changed to follow the common schema and have PCI addresses for SATA controllers and SATA addresses for disks. If you're having issues because of this, it's recommended to edit the domain's XML and remove <address type='pci'> from the <disk> elements with <target bus='sata'/> and let libvirt regenerate it properly.
  - libxl: maximum memory fixes
    Fix reporting of domain maximum memory. Fix setting dom0 maximum memory.
  - libxl: fix disk detach when <driver> not specified
  - libxl: fix dom0 autoballooning with Xen 4.8
  - qemu: Allow empty script path to <interface/>
    Historically, this was always allowed. Unfortunately, due to some rework done for 1.3.2 release a bug was dragged in which suddenly stop allowing domain with such configuration to start.

### v3.0.0 (2017-01-17)

- New features
  - Domain events for metadata content changes
    The domain events framework has a new event ID that can be used to get notifications when domain metadata content changes.
  - Event notifications for the secret object
    The secret object now supports event notifications, covering lifcycle changes and secret value changes.
  - New localPtr attribute for "ip" element in network XML
  - qemu: Support QEMU group I/O throttling
    Add the capability to allow group I/O throttling via a new domain <disk> <iotune> subelement "group_name" to allow sharing I/O throttling quota between multiple drives.
  - nss: Introduce libvirt_guest
    New `libvirt_guest` nss module that translates libvirt guest names into IP addresses.
  - daemon: Add support for runtime logging settings adjustment
    Logging-related settings like log outputs and filters can now be adjusted during runtime using the admin interface without the necessity of the daemon's restart.
  - storage: Add virStorageVolInfoFlags API
    Add the API to support using the VIR_STORAGE_VOL_GET_PHYSICAL flag in order to return the host physical size in bytes of the image container in the allocation field of the _virStorageVolInfo structure. The --physical flag has been added to the virsh vol-info command to access the data.
  - libxl: Implement virDomainGetMaxVcpus API
  - storage: Add overwrite flag checking for logical pool
    Add support for the OVERWRITE flags for the logical storage backend including checking for existing data on the target volumes when building a new logical pool on target volume(s).
  - qemu: Add support for guest CPU configuration on s390(x)
- Improvements
  - perf: Add more perf statistics
    Add support to get the count of branch instructions executed, branch misses, bus cycles, stalled frontend cpu cycles, stalled backend cpu cycles, and ref cpu cycles by applications running on the platform.
  - conf: Display <physical> for volume xml
    Add a display of the <physical> size of a disk volume in the output of the volume XML.
  - qemu: Use virtio-pci by default for aarch64 mach-virt guests
    virtio-pci provides several advantages over virtio-mmio, such as the ability to hotplug devices and improved performance. While opting in to virtio-pci has been possible for a while, newly-defined guests will now use it automatically.
  - vbox: remove support for VirtualBox 3.x and older
    Those old VirtualBox versions have been unsupported by upstream for a long time and the API of 4.0 and newer has diverged enough to require code abstractions to handle differences. Removing support for those old versions drops lots of code from the driver and simplifies the logic to ease implementation of new features going forward.
  - virsh: pool-info: introduce option --bytes
    Add option --bytes to virsh pool-info in order ti allow display of units in bytes rather than default of human readable output.
  - scsi: Add parent wwnn/wwpn or fabric capability for createVport
    Improve the algorithm searching for the parent scsi_host device for vHBA/NPIV scsi_host creation. Rather than supplying the "parent" by name, it's now possible to define the parent by it's wwnn/wwpn or fabric_wwn in the node device create XML or the storage pool XML.
  - qemu: aggregate pcie-root-ports onto multiple functions of a slot
    When pcie-root-ports are added to pcie-root in order to provide a place to connect PCI Express endpoint devices, libvirt now aggregates multiple root ports together onto the same slot (up to 8 per slot) in order to conserve slots. Using this method, it's possible to connect more than 200 endpoint devices to a guest that uses PCIe without requiring setup of any PCIe switches.
- Bug fixes
  - lxc: fix accidental killing of containers during libvirtd restart
    The libvirt_lxc process was previously not moved into the container scope. As a result, if systemd reloads its config after a container is started, when libvirtd is later restarted it will accidentally kill the containers.
  - qemu: Correct GetBlockInfo values
    For an active domain, correct the physical value provided for a raw sparse file backed storage and the allocation value provided for a qcow2 file backed storage that hasn't yet been opened on the domain.
  - qemu: Make virtio console usable on ppc64 guests
    The chardev detection code has been improved and can now handle this configuration properly.
  - qemu: Enable mount namespace
    To avoid funny races with udev relabelling devices under our hands and to enhance security, libvirt now spawns each qemu process with its own `/dev`.
  - storage: Fix implementation of no-overwrite for file system backend
    Fix file system storage backend implementation of the OVERWRITE flags to be consistent between code and documentation. Add checks to ensure that when building a new file system on a target volume that there is not something already on the disk in a format that libvirt can recognize.
  - qemu: Create hugepage path on per domain basis
    Historically, all hugepage enabled domains shared the same path under hugetlbfs. This left libvirt unable to correctly set security labels on it. With this release, however, each domain is put into a separate path which is also correctly labeled.
  - conf: Reject domains with duplicate drive addresses
    Reject duplicate drive addresses for disks and hostdevs at domain definition.
  - libxl: reverse defaults on HVM net device attach
    Fixes network interface attach for HVM domains when no model is specified. Emulated hotplug isn't yet supported and hence we should default to the general working scenario.
  - libxl: always enable pae for x86_64 HVM
    By default pae is disabled in libxl. Without an explicit <pae/> setting in the domain <features> configuration, an x86_64 HVM domain would be get an i686 environment. pae should always be enabled for x86_64 HVM domains.
  - qemu: Fix XML dump of autogenerated websocket
    As a result autogenerated websocket port is regenerated on domain restore, migration and such as it should be.

### v2.5.0 (2016-12-04)

- New features
  - shmem: Add support for additional models
    The shmem device can now utilize QEMU's ivshmem-plain and ivshmem-doorbell, more modern versions of ivshmem.
  - vbox: Add VirtualBox 5.1 support
  - libssh: New transport
    The new libssh transport allows one to connect to a running libvirtd via SSH, using the libssh library; for example: `qemu+libssh://server/system`.
  - vhost-scsi: Add support scsi_host hostdev passthrough
    Add the capability to pass through a scsi_host HBA and the associated LUNs to the guest.
  - Allow debugging of gluster volumes in qemu
    Users can now enable debug logging for native gluster volumes in qemu using the "gluster_debug_level" option in qemu.conf
  - Pre-allocate memory slots for memory hotplug
    Slot numbers for memory devices are now automatically allocated and thus persistent. In addition slot numbers can be specified without providing a base address, which simplifies user configuration
  - qemu: Express devices will be placed on PCIe bus by default
    For machine types that use a PCI Express root bus (e.g. x86_64/Q35 and aarch64/virt), any unaddressed PCI device that is an Express device (all virtio-1.0 devices, e1000e, nec-xhci, vfio assigned devices) will be placed on an Express controller (i.e. a pcie-root-port) instead of a legacy PCI controller (i.e. pci-bridge) with the root ports added as needed.
- Improvements
  - docs: Better documentation for migration APIs and flags
  - vbox: Address thread safety issues
  - virsh: Add support for passing an alternative persistent XML to migrate command
  - vhostuser: Allow hotplug of multiqueue devices
  - NEWS: Switch to an improved format
    List user-visible changes instead of single commits for a better high-level overview of differences between libvirt releases.
  - website: Modernize layout and branding
    The libvirt website looked very cluttered and outdated; it has now been completely overhauled, resulting in a design that's better organized and more pleasant to look at.
- Bug fixes
  - vz: Fix migration in P2P mode
  - Forbid newline character in names of some libvirt objects
  - Fix compilation on macOS

Older libvirt releases didn't have proper release notes, and as such are not included in this page: if you're looking for information about them, start from those made in 2016 and work your way back.