b03d9e9593
<interface> devices (virDomainNetDef) are a bit different from other types of devices in that their actual type may come from a network (in the form of a port connection), and that doesn't happen until the domain is started. This means that any validation of an <interface> at parse time needs to be a bit liberal in what it accepts - when type='network', you could think that something is/isn't allowed, but once the domain is started and a port is created by the configured network, the opposite might be true. To solve this problem hypervisor drivers need to do an extra validation step when the domain is being started. I recently (commit 3cff23f7, libvirt 5.7.0) added a function to peform such validation for all interfaces to the QEMU driver - qemuDomainValidateActualNetDef() - but while that function is a good single point to call for the multiple places that need to "start" an interface (domain startup, device hotplug, device update), it can't be called by the other hypervisor drivers, since 1) it's in the QEMU driver, and 2) it contains some checks specific to QEMU. For validation that applies to network devices on *all* hypervisors, we need yet another interface validation function that can be called by any hypervisor driver (not just QEMU) right after its network port has been created during domain startup or hotplug. This patch adds that function - virDomainActualNetDefValidate(), in the conf directory, and calls it in appropriate places in the QEMU, lxc, and libxl drivers. This new function is the place to put all network device validation that 1) is hypervisor agnostic, and 2) can't be done until we know the "actual type" of an interface. There is no framework for validation at domain startup as there is for post-parse validation, but I don't want to create a whole elaborate system that will only be used by one type of device. For that reason, I just made a single function that should be called directly from the hypervisors, when they are initializing interfaces to start a domain, right after conditionally allocating the network port (and regardless of whether or not that was actually needed). In the case of the QEMU driver, qemuDomainValidateActualNetDef() is already called in all the appropriate places, so we can just call the new function from there. In the case of the other hypervisors, we search for virDomainNetAllocateActualDevice() (which is the hypervisor-agnostic function that calls virNetworkPortCreateXML()), and add the call to our new function right after that. The new function itself could be plunked down into many places in the code, but we already have 3 validation functions for network devices in 2 different places (not counting any basic validation done in virDomainNetDefParseXML() itself): 1) post-parse hypervisor-agnostic (virDomainNetDefValidate() - domain_conf.c:6145) 2) post-parse hypervisor-specific (qemuDomainDeviceDefValidateNetwork() - qemu_domain.c:5498) 3) domain-start hypervisor-specific (qemuDomainValidateActualNetDef() - qemu_domain.c:5390) I placed (3) right next to (2) when I added it, specifically to avoid spreading validation all over the code. For the same reason, I decided to put this new function right next to (1) - this way if someone needs to add validation specific to qemu, they go to one location, and if they need to add validation applying to everyone, they go to the other. It looks a bit strange to have a public function in between a bunch of statics, but I think it's better than the alternative of further fragmentation. (I'm open to other ideas though, of course.) Signed-off-by: Laine Stump <laine@redhat.com> Reviewed-by: Cole Robinson <crobinso@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files COPYING.LESSER
and COPYING for full license terms & conditions.
Installation
Libvirt uses the GNU Autotools build system, so in general can be built and installed with the usual commands, however, we mandate to have the build directory different than the source directory. For example, to build in a manner that is suitable for installing as root, use:
$ mkdir build && cd build
$ ../configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
$ make
$ sudo make install
While to build & install as an unprivileged user
$ mkdir build && cd build
$ ../configure --prefix=$HOME/usr
$ make
$ make install
The libvirt code relies on a large number of 3rd party libraries. These will
be detected during execution of the configure script and a summary printed
which lists any missing (optional) dependencies.
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: