[0/5] KVM: Add a kvm_run flag to signal need for completion

Message

Sean Christopherson Jan. 11, 2025, 1:24 a.m. UTC

Add a flag to kvm_run, KVM_RUN_NEEDS_COMPLETION, that is set by KVM to
inform userspace that KVM_RUN needs to be re-invoked prior to state
save/restore.  The current approach of relying on KVM developers to
update documentation, and on VMM developers to read said documentation,
is brittle and error prone.

Note, this series is *very* lightly tested (borderline RFC).

Sean Christopherson (5):
  KVM: x86: Document that KVM_EXIT_HYPERCALL requires completion
  KVM: Clear vcpu->run->flags at start of KVM_RUN for all architectures
  KVM: Add a common kvm_run flag to communicate an exit needs completion
  KVM: selftests: Provide separate helper for KVM_RUN with
    immediate_exit
  KVM: selftests: Rely on KVM_RUN_NEEDS_COMPLETION to complete userspace
    exits

 Documentation/virt/kvm/api.rst                | 77 ++++++++++++-------
 arch/arm64/kvm/arm.c                          |  1 -
 arch/arm64/kvm/handle_exit.c                  |  2 +-
 arch/powerpc/kvm/book3s_emulate.c             |  1 +
 arch/powerpc/kvm/book3s_hv.c                  |  5 +-
 arch/powerpc/kvm/book3s_pr.c                  |  2 +
 arch/powerpc/kvm/booke.c                      |  1 +
 arch/x86/include/uapi/asm/kvm.h               |  7 +-
 arch/x86/kvm/x86.c                            |  3 +-
 include/uapi/linux/kvm.h                      |  3 +
 .../testing/selftests/kvm/include/kvm_util.h  | 13 +++-
 tools/testing/selftests/kvm/lib/kvm_util.c    |  6 +-
 .../testing/selftests/kvm/lib/ucall_common.c  |  2 +-
 .../testing/selftests/kvm/lib/x86/processor.c |  8 +-
 .../kvm/x86/nested_exceptions_test.c          |  3 +-
 .../kvm/x86/triple_fault_event_test.c         |  3 +-
 virt/kvm/kvm_main.c                           |  4 +
 17 files changed, 90 insertions(+), 51 deletions(-)


base-commit: 10b2c8a67c4b8ec15f9d07d177f63b563418e948