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

Message

Vitaly Kuznetsov April 19, 2021, 4 p.m. UTC

Changes since RFC:
- KVM_CAP_HYPERV_ENFORCE_CPUID introduced. Turns out that at least QEMU
  is not doing a great job setting Hyper-V CPUID entries for various
  configurations (when not all enlightenments are enabled).
- Added a selftest.
- Add Wei's A-b tag to PATCH1.

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