When commit 0bacd8b304 ('i386: Don't set CPUClass::cpu_def on
"max" model') removed the CPUClass::cpu_def field, we kept using
the x86_cpu_load_def() helper directly in max_x86_cpu_initfn(),
emulating the previous behavior when CPUClass::cpu_def was set.
However, x86_cpu_load_def() is intended to help initialization of
CPU models from the builtin_x86_defs table, and does lots of
other steps that are not necessary for "max".
One of the things x86_cpu_load_def() do is to set the properties
listed at tcg_default_props/kvm_default_props. We must not do
that on the "max" CPU model, otherwise under KVM we will
incorrectly report all KVM features as always available, and the
"svm" feature as always unavailable. The latter caused the bug
reported at:
https://bugzilla.redhat.com/show_bug.cgi?id=1467599
("Unable to start domain: the CPU is incompatible with host CPU:
Host CPU does not provide required features: svm")
Replace x86_cpu_load_def() with simple object_property_set*()
calls. In addition to fixing the above bug, this makes the KVM
branch in max_x86_cpu_initfn() very similar to the existing TCG
branch.
For reference, the full list of steps performed by
x86_cpu_load_def() is:
* Setting min-level and min-xlevel. Already done by
max_x86_cpu_initfn().
* Setting family/model/stepping/model-id. Done by the code added
to max_x86_cpu_initfn() in this patch.
* Copying def->features. Wrong because "-cpu max" features need to
be calculated at realize time. This was not a problem in the
current code because host_cpudef.features was all zeroes.
* x86_cpu_apply_props() calls. This causes the bug above, and
shouldn't be done.
* Setting CPUID_EXT_HYPERVISOR. Not needed because it is already
reported by x86_cpu_get_supported_feature_word(), and because
"-cpu max" features need to be calculated at realize time.
* Setting CPU vendor to host CPU vendor if on KVM mode.
Redundant, because max_x86_cpu_initfn() already sets it to the
host CPU vendor.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170712162058.10538-5-ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
http://qemu-project.org/Hosts/Linux
http://qemu-project.org/Hosts/Mac
http://qemu-project.org/Hosts/W32
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
git clone git://git.qemu-project.org/qemu.git
When submitting patches, the preferred approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.
Additional information on submitting patches can be found online via
the QEMU website
http://qemu-project.org/Contribute/SubmitAPatch
http://qemu-project.org/Contribute/TrivialPatches
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
https://bugs.launchpad.net/qemu/
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
http://qemu-project.org/Contribute/ReportABug
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
- qemu-devel@nongnu.org
http://lists.nongnu.org/mailman/listinfo/qemu-devel
- #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
http://qemu-project.org/Contribute/StartHere
-- End
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