On Fri, 8 Sep 2023 14:45:24 +0200 Tim Wiederhake <twied...@redhat.com> wrote:
> Synchronizing the list of cpu features and models with qemu is a recurring > task in libvirt. For x86, this is done by reading qom-list-properties for > max-x86_64-cpu and manually filtering out everthing that does not look like > a feature name, as well as parsing target/i386/cpu.c for cpu models. modulo fixing typos/name conflicts in 1st 3 patches, I don't think it's a great idea for libvirt (or any other user) to parse QEMU source (whether it's C code or yaml) or other way around for users to influence QEMU internals. QEMU does provides QMP interface for introspection of CPU models and it should be used as a mean to discover new CPU models as well as new feature names. If something is missing there we should fix it up to make it usable for libvirt. > This is a flawed, tedious and error-prone procedure. Ideally, qemu > and libvirt would query a common source for cpu feature and model > related information. Meanwhile, converting this information into an easier > to parse format would help libvirt a lot. > > This patch series converts the cpu feature information present in > target/i386/cpu.c (`feature_word_info`) into a yaml file and adds a > script to generate the c code from this data. > A patch set to convert the cpu model data (`builtin_x86_defs`) in the > same way will follow. while theoretically you can parse feature_word_info with some sort of reliability, you can't do that reliably with CPU model definitions in builtin_x86_defs as the later is just a skeleton. Actual CPU models definitions are a function of used machine type, accelerator and host kernel. > > v1: https://lists.nongnu.org/archive/html/qemu-devel/2023-08/msg02005.html > > Changes since v1: > * Incorporated changes from > https://lists.nongnu.org/archive/html/qemu-devel/2023-08/msg04241.html. > * Changed data format from xml to yaml, as proposed in > https://lists.nongnu.org/archive/html/qemu-devel/2023-09/msg01033.html. > Using json has some drawbacks, see > https://lists.nongnu.org/archive/html/qemu-devel/2023-08/msg03384.html. > * Rebased on top of current master. Features added in the meantime: > amx-complex and vmx-enable-user-wait-pause > * Split up the reformatting of feature_word_info.c.inc to make it easier > to review. These patches could be squashed together before merging. > > Tim Wiederhake (10): > target/i386: Add missing feature names in FEAT_VMX_EPT_VPID_CAPS > target/i386: Fix feature names in FEAT_VMX_EPT_VPID_CAPS > target/i386: Fix duplicated feature name in FEAT_KVM > target/i386: Split out feature_word_info > target/i386: Translate feature_word_info to yaml > target/i386: Format feature_word_info.c.inc: Remove comments > target/i386: Format feature_word_info.c.inc: feat_names > target/i386: Format feature_word_info.c.inc: Unfold cpuid member > target/i386: Format feature_word_info.c.inc: Whitespaces and trailing > commas > target/i386: Autogenerate feature_word_info.c.inc > > target/i386/cpu.c | 677 +----------------- > target/i386/feature_word_info.c.inc | 1030 +++++++++++++++++++++++++++ > target/i386/feature_word_info.py | 62 ++ > target/i386/feature_word_info.yaml | 697 ++++++++++++++++++ > 4 files changed, 1790 insertions(+), 676 deletions(-) > create mode 100644 target/i386/feature_word_info.c.inc > create mode 100755 target/i386/feature_word_info.py > create mode 100644 target/i386/feature_word_info.yaml >
