[00/12] KVM: x86: Add "governed" X86_FEATURE framework

Message

Sean Christopherson Feb. 17, 2023, 11:10 p.m. UTC

Add a framework to manage and cache KVM-governed features, i.e. CPUID
based features that require explicit KVM enabling and/or need to be
queried semi-frequently by KVM.  The idea originally came up in the
context of the architectural LBRs series as a way to avoid querying
guest CPUID in hot paths without needing a dedicated flag, but as
evidenced by the shortlog, the most common usage is to handle the ever-
growing list of SVM features that are exposed to L1.

Note, I don't like the name "governed", but it was the least awful thing I
could come up with.  Suggestions most definitely welcome.

This series is lightly tested.  I am posting somewhat speculatively to get
early feedback on the idea.

Sean Christopherson (12):
  KVM: x86: Add a framework for enabling KVM-governed x86 features
  KVM: x86/mmu: Use KVM-governed feature framework to track "GBPAGES
    enabled"
  KVM: VMX: Recompute "XSAVES enabled" only after CPUID update
  KVM: VMX: Rename XSAVES control to follow KVM's preferred "ENABLE_XYZ"
  KVM: x86: Use KVM-governed feature framework to track "XSAVES enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "NRIPS enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "TSC scaling
    enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "vVM{SAVE,LOAD}
    enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "LBRv enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "Pause Filter
    enabled"
  KVM: nSVM: Use KVM-governed feature framework to track "vGIF enabled"
  KVM: x86: Disallow guest CPUID lookups when IRQs are disabled

 arch/x86/include/asm/kvm_host.h  | 11 ++++++
 arch/x86/include/asm/vmx.h       |  2 +-
 arch/x86/kvm/cpuid.c             | 31 +++++++++++++++++
 arch/x86/kvm/cpuid.h             | 51 ++++++++++++++++++++++++++++
 arch/x86/kvm/governed_features.h | 19 +++++++++++
 arch/x86/kvm/mmu/mmu.c           | 20 ++---------
 arch/x86/kvm/svm/nested.c        | 48 ++++++++++++++++-----------
 arch/x86/kvm/svm/svm.c           | 57 +++++++++++++++++++++-----------
 arch/x86/kvm/svm/svm.h           | 13 ++------
 arch/x86/kvm/vmx/capabilities.h  |  2 +-
 arch/x86/kvm/vmx/hyperv.h        |  2 +-
 arch/x86/kvm/vmx/nested.c        |  6 ++--
 arch/x86/kvm/vmx/nested.h        |  2 +-
 arch/x86/kvm/vmx/vmx.c           | 48 +++++++++++++--------------
 arch/x86/kvm/vmx/vmx.h           |  2 +-
 arch/x86/kvm/x86.c               |  4 +--
 16 files changed, 217 insertions(+), 101 deletions(-)
 create mode 100644 arch/x86/kvm/governed_features.h


base-commit: 62ef199250cd46fb66fe98267137b7f64e0b41b4