Changes since RFCv1: - Took a slightly differenet approach, instead of adding all missing Hyper-V feature leaves to feature_word_info[] remove the existing ones from there. The logic for handling them is very different and some of these leaves are not actually 'feature leaves'. See "i386: drop FEAT_HYPERV feature leaves" for details. - x86_cpu_hyperv_realize introduced [Eduardo]. - Rebased to the latest master.
This pairs with https://lore.kernel.org/kvm/20200929150944.1235688-1-vkuzn...@redhat.com/T/#t and as KVM part is not yet fully accepted, sending this as RFC. Upper layer tools like libvirt want to figure out which Hyper-V features are supported by the underlying stack (QEMU/KVM) but currently they are unable to do so. We have a nice 'hv_passthrough' CPU flag supported by QEMU but it has no effect on e.g. QMP's query-cpu-model-expansion type=full model={"name":"host","props":{"hv-passthrough":true}} command as we parse Hyper-V features after creating KVM vCPUs and not at feature expansion time. To support the use-case we first need to make KVM_GET_SUPPORTED_HV_CPUID ioctl a system-wide ioctl as the existing vCPU version can't be used that early. This is what KVM part does. With that done, we can make early Hyper-V feature expansion (this series). Vitaly Kuznetsov (19): WIP: update linux/headers i386: fill in FEAT_HYPERV_EDX from edx instead of eax i386: drop x86_cpu_get_supported_feature_word() forward declaration i386: move hyperv_vendor_id initialization to x86_cpu_realizefn() i386: move hyperv_interface_id initialization to x86_cpu_realizefn() i386: move hyperv_version_id initialization to x86_cpu_realizefn() i386: move hyperv_limits initialization to x86_cpu_realizefn() i386: keep hyperv_vendor string up-to-date i386: invert hyperv_spinlock_attempts setting logic with hv_passthrough i386: always fill Hyper-V CPUID feature leaves from X86CPU data i386: introduce hv_cpuid_cache i386: drop FEAT_HYPERV feature leaves i386: split hyperv_handle_properties() into hyperv_expand_features()/hyperv_fill_cpuids() i386: move eVMCS enablement to hyperv_init_vcpu() i386: switch hyperv_expand_features() to using error_setg() i386: adjust the expected KVM_GET_SUPPORTED_HV_CPUID array size i386: prefer system KVM_GET_SUPPORTED_HV_CPUID ioctl over vCPU's one i386: use global kvm_state in hyperv_enabled() check i386: expand Hyper-V features during CPU feature expansion time linux-headers/asm-x86/kvm.h | 20 ++ linux-headers/linux/kvm.h | 27 +- target/i386/cpu.c | 135 +++------ target/i386/cpu.h | 12 +- target/i386/kvm-stub.c | 5 + target/i386/kvm.c | 526 ++++++++++++++++++++---------------- target/i386/kvm_i386.h | 1 + 7 files changed, 398 insertions(+), 328 deletions(-) -- 2.25.4
