[v6,0/4] KVM: x86: Convey the exit reason, etc. to user-space on emulation failure

Message

David Edmondson Sept. 20, 2021, 10:37 a.m. UTC

To help when debugging failures in the field, if instruction emulation
fails, report the VM exit reason, etc. to userspace in order that it
can be recorded.

The SGX changes here are compiled but untested.

v6:
- More Reviewed-by (Sean).
- Fix "From" (d'oh!).

v5:
- Add some Reviewed-by (Sean).
- Build-time complaint about sizing rather than run-time calculation (Sean).
- Clarify that the format of the auxiliary debug data is undefined (Sean).
- ndata_start -> info_start (Sean).
- sizeof(variable) rather than sizeof(type) (Sean).

v4:
- Update the API for preparing emulation failure report (Sean)
- sgx uses the provided API in all relevant cases (Sean)
- Clarify the intended layout of kvm_run.emulation_failure.

v3:
- Convey any debug data un-flagged after the ABI specified data in
  struct emulation_failure (Sean)
- Obey the ABI protocol in sgx_handle_emulation_failure() (Sean)

v2:
- Improve patch comments (dmatlock)
- Intel should provide the full exit reason (dmatlock)
- Pass a boolean rather than flags (dmatlock)
- Use the helper in kvm_task_switch() and kvm_handle_memory_failure()
  (dmatlock)
- Describe the exit_reason field of the emulation_failure structure
  (dmatlock)

David Edmondson (4):
  KVM: x86: Clarify the kvm_run.emulation_failure structure layout
  KVM: x86: Get exit_reason as part of kvm_x86_ops.get_exit_info
  KVM: x86: On emulation failure, convey the exit reason, etc. to
    userspace
  KVM: x86: SGX must obey the KVM_INTERNAL_ERROR_EMULATION protocol

 arch/x86/include/asm/kvm_host.h | 10 +++--
 arch/x86/kvm/svm/svm.c          |  8 ++--
 arch/x86/kvm/trace.h            |  9 ++--
 arch/x86/kvm/vmx/nested.c       |  2 +-
 arch/x86/kvm/vmx/sgx.c          | 16 +++-----
 arch/x86/kvm/vmx/vmx.c          | 11 +++--
 arch/x86/kvm/x86.c              | 73 ++++++++++++++++++++++++++-------
 include/uapi/linux/kvm.h        | 14 ++++++-
 8 files changed, 99 insertions(+), 44 deletions(-)