Changes since v3: - Rebase to the latest kvm/queue (KVM_CAP_SYS_HYPERV_CPUID changed to 191)
QEMU series using the feature: https://lists.gnu.org/archive/html/qemu-devel/2020-09/msg02017.html Original description: KVM_GET_SUPPORTED_HV_CPUID was initially implemented as a vCPU ioctl but this is not very useful when VMM is just trying to query which Hyper-V features are supported by the host prior to creating VM/vCPUs. The data in KVM_GET_SUPPORTED_HV_CPUID is mostly static with a few exceptions but it seems we can change this. Add support for KVM_GET_SUPPORTED_HV_CPUID as a system ioctl as well. QEMU specific description: In some cases QEMU needs to collect the information about which Hyper-V features are supported by KVM and pass it up the stack. For non-hyper-v features this is done with system-wide KVM_GET_SUPPORTED_CPUID/ KVM_GET_MSRS ioctls but Hyper-V specific features don't get in the output (as Hyper-V CPUIDs intersect with KVM's). In QEMU, CPU feature expansion happens before any KVM vcpus are created so KVM_GET_SUPPORTED_HV_CPUID can't be used in its current shape. Vitaly Kuznetsov (2): KVM: x86: hyper-v: allow KVM_GET_SUPPORTED_HV_CPUID as a system ioctl KVM: selftests: test KVM_GET_SUPPORTED_HV_CPUID as a system ioctl Documentation/virt/kvm/api.rst | 16 ++-- arch/x86/kvm/hyperv.c | 6 +- arch/x86/kvm/hyperv.h | 4 +- arch/x86/kvm/vmx/evmcs.c | 3 +- arch/x86/kvm/x86.c | 45 ++++++---- include/uapi/linux/kvm.h | 3 +- .../testing/selftests/kvm/include/kvm_util.h | 2 + tools/testing/selftests/kvm/lib/kvm_util.c | 26 ++++++ .../selftests/kvm/x86_64/hyperv_cpuid.c | 87 +++++++++++-------- 9 files changed, 123 insertions(+), 69 deletions(-) -- 2.25.4
