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2f5b76bce5
As preparation for merging cache_info_cpuid4 and cache_info_amd in
X86CPUState, set legacy cache model based on vendor in the CPUID 0x2
leaf. For AMD CPU, select legacy AMD cache model (in cache_info_amd) as
the default cache model, otherwise, select legacy Intel cache model (in
cache_info_cpuid4) as before.
To ensure compatibility is not broken, add an enable_legacy_vendor_cache
flag based on x-vendor-only-v2 to indicate cases where the legacy cache
model should be used regardless of the vendor. For CPUID 0x2 leaf,
enable_legacy_vendor_cache flag indicates to pick legacy Intel cache
model, which is for compatibility with the behavior of PC machine v10.0
and older.
The following explains how current vendor-based default legacy cache
model ensures correctness without breaking compatibility.
* For the PC machine v6.0 and older, vendor_cpuid_only=false, and
vendor_cpuid_only_v2=false.
- If the named CPU model has its own cache model, and doesn't use
legacy cache model (legacy_cache=false), then cache_info_cpuid4 and
cache_info_amd are same, so 0x2 leaf uses its own cache model
regardless of the vendor.
- For max/host/named CPU (without its own cache model), then the flag
enable_legacy_vendor_cache is true, they will use legacy Intel cache
model just like their previous behavior.
* For the PC machine v10.0 and older (to v6.1), vendor_cpuid_only=true,
and vendor_cpuid_only_v2=false.
- If the named CPU model has its own cache model (legacy_cache=false),
then cache_info_cpuid4 & cache_info_amd both equal to its own cache
model, so it uses its own cache model in 0x2 leaf regardless of the
vendor. Only AMD CPUs have all-0 leaf due to vendor_cpuid_only=true,
and this is exactly the behavior of these old machines.
- For max/host/named CPU (without its own cache model), then the flag
enable_legacy_vendor_cache is true, they will use legacy Intel cache
model. Similarly, only AMD CPUs have all-0 leaf, and this is exactly
the behavior of these old machines.
* For the PC machine v10.1 and newer, vendor_cpuid_only=true, and
vendor_cpuid_only_v2=true.
- If the named CPU model has its own cache model (legacy_cache=false),
then cache_info_cpuid4 & cache_info_amd both equal to its own cache
model, so it uses its own cache model in 0x2 leaf regardless of the
vendor. And AMD CPUs have all-0 leaf. Nothing will change.
- For max/host/named CPU (without its own cache model), then the flag
enable_legacy_vendor_cache is false, the legacy cache model is
selected based on vendor.
For AMD CPU, it will use legacy AMD cache but still get all-0 leaf
due to vendor_cpuid_only=true.
For non-AMD (Intel/Zhaoxin) CPU, it will use legacy Intel cache as
expected.
Here, selecting the legacy cache model based on the vendor does not
change the previous (before the change) behavior.
Therefore, the above analysis proves that, with the help of the flag
enable_legacy_vendor_cache, it is acceptable to select the default
legacy cache model based on the vendor.
For the CPUID 0x2 leaf, in X86CPUState, a unified cache_info is enough.
It only needs to be initialized and configured with the corresponding
legacy cache model based on the vendor.
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250711102143.1622339-14-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| docs | ||
| dump | ||
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| fpu | ||
| fsdev | ||
| gdb-xml | ||
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| host/include | ||
| hw | ||
| include | ||
| io | ||
| libdecnumber | ||
| linux-headers | ||
| linux-user | ||
| migration | ||
| monitor | ||
| nbd | ||
| net | ||
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| replay | ||
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| stats | ||
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| system | ||
| target | ||
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| tools | ||
| trace | ||
| ui | ||
| util | ||
| .b4-config | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .exrc | ||
| .gdbinit | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .gitmodules | ||
| .gitpublish | ||
| .mailmap | ||
| .patchew.yml | ||
| .readthedocs.yml | ||
| .travis.yml | ||
| block.c | ||
| blockdev-nbd.c | ||
| blockdev.c | ||
| blockjob.c | ||
| clippy.toml | ||
| configure | ||
| COPYING | ||
| COPYING.LIB | ||
| cpu-common.c | ||
| cpu-target.c | ||
| event-loop-base.c | ||
| gitdm.config | ||
| hmp-commands-info.hx | ||
| hmp-commands.hx | ||
| iothread.c | ||
| job-qmp.c | ||
| job.c | ||
| Kconfig | ||
| Kconfig.host | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| meson.build | ||
| meson_options.txt | ||
| module-common.c | ||
| os-posix.c | ||
| os-wasm.c | ||
| os-win32.c | ||
| page-target.c | ||
| page-vary-common.c | ||
| page-vary-target.c | ||
| pythondeps.toml | ||
| qemu-bridge-helper.c | ||
| qemu-edid.c | ||
| qemu-img-cmds.hx | ||
| qemu-img.c | ||
| qemu-io-cmds.c | ||
| qemu-io.c | ||
| qemu-keymap.c | ||
| qemu-nbd.c | ||
| qemu-options.hx | ||
| qemu.nsi | ||
| qemu.sasl | ||
| README.rst | ||
| replication.c | ||
| target-info-stub.c | ||
| target-info.c | ||
| trace-events | ||
| VERSION | ||
| version.rc | ||
=========== 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. Documentation ============= Documentation can be found hosted online at `<https://www.qemu.org/documentation/>`_. The documentation for the current development version that is available at `<https://www.qemu.org/docs/master/>`_ is generated from the ``docs/`` folder in the source tree, and is built by `Sphinx <https://www.sphinx-doc.org/en/master/>`_. 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: .. code-block:: shell mkdir build cd build ../configure make Additional information can also be found online via the QEMU website: * `<https://wiki.qemu.org/Hosts/Linux>`_ * `<https://wiki.qemu.org/Hosts/Mac>`_ * `<https://wiki.qemu.org/Hosts/W32>`_ Submitting patches ================== The QEMU source code is maintained under the GIT version control system. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu.git When submitting patches, one common 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 `style section <https://www.qemu.org/docs/master/devel/style.html>`_ of the Developers Guide. Additional information on submitting patches can be found online via the QEMU website: * `<https://wiki.qemu.org/Contribute/SubmitAPatch>`_ * `<https://wiki.qemu.org/Contribute/TrivialPatches>`_ The QEMU website is also maintained under source control. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu-web.git * `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_ A 'git-publish' utility was created to make above process less cumbersome, and is highly recommended for making regular contributions, or even just for sending consecutive patch series revisions. It also requires a working 'git send-email' setup, and by default doesn't automate everything, so you may want to go through the above steps manually for once. For installation instructions, please go to: * `<https://github.com/stefanha/git-publish>`_ The workflow with 'git-publish' is: .. code-block:: shell $ git checkout master -b my-feature $ # work on new commits, add your 'Signed-off-by' lines to each $ git publish Your patch series will be sent and tagged as my-feature-v1 if you need to refer back to it in the future. Sending v2: .. code-block:: shell $ git checkout my-feature # same topic branch $ # making changes to the commits (using 'git rebase', for example) $ git publish Your patch series will be sent with 'v2' tag in the subject and the git tip will be tagged as my-feature-v2. Bug reporting ============= The QEMU project uses GitLab issues to track bugs. Bugs found when running code built from QEMU git or upstream released sources should be reported via: * `<https://gitlab.com/qemu-project/qemu/-/issues>`_ 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 GitLab. For additional information on bug reporting consult: * `<https://wiki.qemu.org/Contribute/ReportABug>`_ ChangeLog ========= For version history and release notes, please visit `<https://wiki.qemu.org/ChangeLog/>`_ or look at the git history for more detailed information. Contact ======= The QEMU community can be contacted in a number of ways, with the two main methods being email and IRC: * `<mailto:qemu-devel@nongnu.org>`_ * `<https://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: * `<https://wiki.qemu.org/Contribute/StartHere>`_