Daniel Henrique Barboza 9665b27dba qemuProcessRefreshCPU: skip 'host-model' logic for pSeries guests
Commit v3.10.0-182-g237f045d9a ("qemu: Ignore fallback CPU attribute
on reconnect") forced CPU 'fallback' to ALLOW, regardless of user
choice. This fixed a situation in which guests created with older
Libvirt versions, which used CPU mode 'host-model' in runtime, would
fail to launch in a newer Libvirt if the fallback was set to FORBID.
This would lead to a scenario where the CPU was translated to 'host-model'
to 'custom', but then the FORBID setting would make the translation
process fail.

PSeries can operate with 'host-model' in runtime due to specific PPC64
mechanics regarding compatibility mode. The update() implementation of
the cpuDriverPPC64 driver is a NO-OP if CPU mode is 'host-model', and
the driver does not implement translate(). The commit mentioned above
is causing PSeries guests to get their 'fallback' setting to ALLOW,
overwriting user choice, exposing a design problem in
qemuProcessRefreshCPU() - for PSeries guests, handling 'host-model'
as it is being done does not apply.

All other cpuArchDrivers implements update() and changes guest mode
to VIR_CPU_MODE_CUSTOM, meaning that PSeries is currently the only
exception to this logic. Let's make it official.

https://bugzilla.redhat.com/show_bug.cgi?id=1660711

Suggested-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20200525123945.4049591-2-danielhb413@gmail.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
2020-05-25 16:20:25 +02:00
2019-05-31 17:54:28 +02:00
2019-09-06 12:47:46 +02:00
2020-01-16 13:04:11 +00:00
2019-06-07 13:18:08 +02:00
2019-12-19 16:42:06 +01:00
2019-10-18 17:32:52 +02:00
2019-12-20 12:25:42 -05:00

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==============================
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:

https://libvirt.org


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
============

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

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:

https://libvirt.org/contact.html
Description
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.
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