Re: [PATCH v2 00/30] KVM: x86: hyper-v: Fine-grained access check to Hyper-V hypercalls and MSRs

[Paolo Bonzini]

On 21/05/21 11:51, Vitaly Kuznetsov wrote:
> Changes since v1:
> - Rebase to kvm/next.
>
> Original description:
>
> Currently, all implemented Hyper-V features (MSRs and hypercalls) are
> available unconditionally to all Hyper-V enabled guests. This is not
> ideal as KVM userspace may decide to provide only a subset of the
> currently implemented features to emulate an older Hyper-V version,
> to reduce attack surface,... Implement checks against guest visible
> CPUIDs for all currently implemented MSRs and hypercalls.
>
> Vitaly Kuznetsov (30):
>    asm-generic/hyperv: add HV_STATUS_ACCESS_DENIED definition
>    KVM: x86: hyper-v: Introduce KVM_CAP_HYPERV_ENFORCE_CPUID
>    KVM: x86: hyper-v: Cache guest CPUID leaves determining features
>      availability
>    KVM: x86: hyper-v: Prepare to check access to Hyper-V MSRs
>    KVM: x86: hyper-v: Honor HV_MSR_HYPERCALL_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_VP_RUNTIME_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_TIME_REF_COUNT_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_VP_INDEX_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_RESET_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_REFERENCE_TSC_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_SYNIC_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_SYNTIMER_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_MSR_APIC_ACCESS_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Honor HV_ACCESS_FREQUENCY_MSRS privilege bit
>    KVM: x86: hyper-v: Honor HV_ACCESS_REENLIGHTENMENT privilege bit
>    KVM: x86: hyper-v: Honor HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
>      privilege bit
>    KVM: x86: hyper-v: Honor HV_FEATURE_DEBUG_MSRS_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Inverse the default in hv_check_msr_access()
>    KVM: x86: hyper-v: Honor HV_STIMER_DIRECT_MODE_AVAILABLE privilege bit
>    KVM: x86: hyper-v: Prepare to check access to Hyper-V hypercalls
>    KVM: x86: hyper-v: Check access to HVCALL_NOTIFY_LONG_SPIN_WAIT
>      hypercall
>    KVM: x86: hyper-v: Honor HV_POST_MESSAGES privilege bit
>    KVM: x86: hyper-v: Honor HV_SIGNAL_EVENTS privilege bit
>    KVM: x86: hyper-v: Honor HV_DEBUGGING privilege bit
>    KVM: x86: hyper-v: Honor HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED bit
>    KVM: x86: hyper-v: Honor HV_X64_CLUSTER_IPI_RECOMMENDED bit
>    KVM: x86: hyper-v: Honor HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED bit
>    KVM: selftests: move Hyper-V MSR definitions to hyperv.h
>    KVM: selftests: Move evmcs.h to x86_64/
>    KVM: selftests: Introduce hyperv_features test
>
>   Documentation/virt/kvm/api.rst                |  11 +
>   arch/x86/include/asm/kvm_host.h               |   9 +
>   arch/x86/kvm/hyperv.c                         | 216 +++++-
>   arch/x86/kvm/hyperv.h                         |   1 +
>   arch/x86/kvm/x86.c                            |   4 +
>   include/asm-generic/hyperv-tlfs.h             |   1 +
>   include/uapi/linux/kvm.h                      |   1 +
>   tools/testing/selftests/kvm/.gitignore        |   1 +
>   tools/testing/selftests/kvm/Makefile          |   1 +
>   .../kvm/include/{ => x86_64}/evmcs.h          |   2 +-
>   .../selftests/kvm/include/x86_64/hyperv.h     | 185 +++++
>   .../selftests/kvm/x86_64/hyperv_clock.c       |   8 +-
>   .../selftests/kvm/x86_64/hyperv_features.c    | 649 ++++++++++++++++++
>   13 files changed, 1071 insertions(+), 18 deletions(-)
>   rename tools/testing/selftests/kvm/include/{ => x86_64}/evmcs.h (99%)
>   create mode 100644 tools/testing/selftests/kvm/include/x86_64/hyperv.h
>   create mode 100644 tools/testing/selftests/kvm/x86_64/hyperv_features.c

Queued, thanks.

Paolo