958ac3c42b
From CPUState.nr_cores' comment, it represents "number of cores within
this CPU package".
After 003f230e37d7 ("machine: Tweak the order of topology members in
struct CpuTopology"), the meaning of smp.cores changed to "the number of
cores in one die", but this commit missed to change CPUState.nr_cores'
calculation, so that CPUState.nr_cores became wrong and now it
misses to consider numbers of clusters and dies.
At present, only i386 is using CPUState.nr_cores.
But as for i386, which supports die level, the uses of CPUState.nr_cores
are very confusing:
Early uses are based on the meaning of "cores per package" (before die
is introduced into i386), and later uses are based on "cores per die"
(after die's introduction).
This difference is due to that commit a94e1428991f ("target/i386: Add
CPUID.1F generation support for multi-dies PCMachine") misunderstood
that CPUState.nr_cores means "cores per die" when calculated
CPUID.1FH.01H:EBX. After that, the changes in i386 all followed this
wrong understanding.
With the influence of 003f230e37d7 and a94e1428991f, for i386 currently
the result of CPUState.nr_cores is "cores per die", thus the original
uses of CPUState.cores based on the meaning of "cores per package" are
wrong when multiple dies exist:
1. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.01H:EBX[bits 23:16] is
incorrect because it expects "cpus per package" but now the
result is "cpus per die".
2. In cpu_x86_cpuid() of target/i386/cpu.c, for all leaves of CPUID.04H:
EAX[bits 31:26] is incorrect because they expect "cpus per package"
but now the result is "cpus per die". The error not only impacts the
EAX calculation in cache_info_passthrough case, but also impacts other
cases of setting cache topology for Intel CPU according to cpu
topology (specifically, the incoming parameter "num_cores" expects
"cores per package" in encode_cache_cpuid4()).
3. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.0BH.01H:EBX[bits
15:00] is incorrect because the EBX of 0BH.01H (core level) expects
"cpus per package", which may be different with 1FH.01H (The reason
is 1FH can support more levels. For QEMU, 1FH also supports die,
1FH.01H:EBX[bits 15:00] expects "cpus per die").
4. In cpu_x86_cpuid() of target/i386/cpu.c, when CPUID.80000001H is
calculated, here "cpus per package" is expected to be checked, but in
fact, now it checks "cpus per die". Though "cpus per die" also works
for this code logic, this isn't consistent with AMD's APM.
5. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.80000008H:ECX expects
"cpus per package" but it obtains "cpus per die".
6. In simulate_rdmsr() of target/i386/hvf/x86_emu.c, in
kvm_rdmsr_core_thread_count() of target/i386/kvm/kvm.c, and in
helper_rdmsr() of target/i386/tcg/sysemu/misc_helper.c,
MSR_CORE_THREAD_COUNT expects "cpus per package" and "cores per
package", but in these functions, it obtains "cpus per die" and
"cores per die".
On the other hand, these uses are correct now (they are added in/after
a94e1428991f):
1. In cpu_x86_cpuid() of target/i386/cpu.c, topo_info.cores_per_die
meets the actual meaning of CPUState.nr_cores ("cores per die").
2. In cpu_x86_cpuid() of target/i386/cpu.c, vcpus_per_socket (in CPUID.
04H's calculation) considers number of dies, so it's correct.
3. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.1FH.01H:EBX[bits
15:00] needs "cpus per die" and it gets the correct result, and
CPUID.1FH.02H:EBX[bits 15:00] gets correct "cpus per package".
When CPUState.nr_cores is correctly changed to "cores per package" again
, the above errors will be fixed without extra work, but the "currently"
correct cases will go wrong and need special handling to pass correct
"cpus/cores per die" they want.
Fix CPUState.nr_cores' calculation to fit the original meaning "cores
per package", as well as changing calculation of topo_info.cores_per_die,
vcpus_per_socket and CPUID.1FH.
Fixes: a94e1428991f ("target/i386: Add CPUID.1F generation support for multi-dies PCMachine")
Fixes: 003f230e37d7 ("machine: Tweak the order of topology members in struct CpuTopology")
Signed-off-by: Zhuocheng Ding <zhuocheng.ding@intel.com>
Co-developed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20231024090323.1859210-4-zhao1.liu@linux.intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
=========== 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>`_