Re: [kvm-unit-tests PATCH 2/2] x86: nVMX: Set guest as active after NMI/INTR-window tests

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Thu, May 09, 2019 at 02:29:45PM -0700, Nadav Amit wrote:
> > On May 9, 2019, at 1:32 PM, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> > 
> > On Wed, May 08, 2019 at 03:27:15AM -0700, Nadav Amit wrote:
> >> From: Nadav Amit <nadav.amit@gmail.com>
> >> 
> >> Intel SDM 26.6.5 says regarding interrupt-window exiting that: "These
> >> events wake the logical processor if it just entered the HLT state
> >> because of a VM entry." A similar statement is told about NMI-window
> >> exiting.
> >> 
> >> However, running tests which are similar to verify_nmi_window_exit() and
> >> verify_intr_window_exit() on bare-metal suggests that real CPUs do not
> >> wake up. Until someone figures what the correct behavior is, just reset
> >> the activity state to "active" after each test to prevent the whole
> >> test-suite from getting stuck.
> >> 
> >> Cc: Jim Mattson <jmattson@google.com>
> >> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> >> Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
> >> ---
> >> x86/vmx_tests.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >> 
> >> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> >> index f921286..2d6b12d 100644
> >> --- a/x86/vmx_tests.c
> >> +++ b/x86/vmx_tests.c
> >> @@ -7063,6 +7063,7 @@ static void verify_nmi_window_exit(u64 rip)
> >> 	report("Activity state (%ld) is 'ACTIVE'",
> >> 	       vmcs_read(GUEST_ACTV_STATE) == ACTV_ACTIVE,
> >> 	       vmcs_read(GUEST_ACTV_STATE));
> >> +	vmcs_write(GUEST_ACTV_STATE, ACTV_ACTIVE);
> > 
> > Don't you need to remove (or modify) the above report() as well to avoid
> > failing the current test?
> 
> Thanks for checking it (in your second email).
> 
> So should I remove this test completely for v2? Or do you have any different
> test you want to run?

I'd say just remove the activity state check.  KVM is technically broken,
and is unlikely to be fixed any time soon.  I don't see much value in
adding more code to the test just to highlight that KVM doesn't strictly
adhere to the SDM for activity state transitions.