On Tue, Aug 28, 2018 at 9:04 AM, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: > Write VM_EXIT_CONTROLS using vm_exit_controls_init() when configuring > vmcs02, otherwise vm_exit_controls_shadow will be stale. EFER in > particular can be corrupted if VM_EXIT_LOAD_IA32_EFER is not updated > due to an incorrect shadow optimization, which can crash L0 due to > EFER not being loaded on exit. This does not occur with the current > code base simply because update_transition_efer() unconditionally > clears VM_EXIT_LOAD_IA32_EFER before conditionally setting it, and > because a nested guest always starts with VM_EXIT_LOAD_IA32_EFER > clear, i.e. we'll only ever unnecessarily clear the bit. That is, > until someone optimizes update_transition_efer()... > > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> Doesn't this also imply that we need a vm_exit_controls_init() when returning to vmcs01, or vm_exit_controls_shadow will be stale after an emulated VM-exit?
