On Wed, Sep 19, 2018 at 02:00:04PM -0700, Jim Mattson wrote: > 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? Yep. It's in the next patch, 04/18. IIRC I put it in a separate patch because there were multiple shadow/cache resets missing and resetting the shadows seemed to be distinctly different from initializing the exit controls shadows.
