86a8e5a84c
Linux kernel 5.1 added a new PPC KVM capability named KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST, which is exposed to the QEMU guest since QEMU commit 8ff43ee404d under a new sPAPR capability called SPAPR_CAP_CCF_ASSIST. This cap indicates whether the processor supports hardware acceleration for the count cache flush workaround, which is a software workaround that flushes the count cache on context switch. If the processor has this hardware acceleration, the software flush can be shortened, resulting in performance gain. This hardware acceleration is defaulted to 'off' in QEMU. The reason is that earlier versions of the Power 9 processor didn't support it (it is available on Power 9 DD2.3 and newer), and defaulting this option to 'on' would break migration compatibility between the Power 9 processor class. However, the user running a P9 DD2.3+ hypervisor might want to create guests with ccf-assist=on, accepting the downside of only being able to migrate them only between other P9 DD2.3+ hosts running upstream kernel 5.1+, to get a performance boost. This patch adds this new capability to Libvirt, with the name of QEMU_CAPS_MACHINE_PSERIES_CAP_CCF_ASSIST. Reviewed-by: Cole Robinson <crobinso@redhat.com> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.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. For example, to build in a manner that is suitable for installing as root, use:
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
$ make
$ sudo make install
While to build & install as an unprivileged user
$ ./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: