Re: [kvm-unit-tests PATCH 1/2] x86: nVMX: Use #DB in nmi and intr tests

[Nadav Amit <nadav.amit@gmail.com>]

> On May 8, 2019, at 4:11 PM, Jim Mattson <jmattson@google.com> wrote:
> 
> From: Nadav Amit <nadav.amit@gmail.com>
> Date: Wed, May 8, 2019 at 10:47 AM
> To: Paolo Bonzini
> Cc: <kvm@vger.kernel.org>, Nadav Amit, Jim Mattson, Sean Christopherson
> 
>> From: Nadav Amit <nadav.amit@gmail.com>
>> 
>> According to Intel SDM 26.3.1.5 "Checks on Guest Non-Register State", if
>> the activity state is HLT, the only events that can be injected are NMI,
>> MTF and "Those with interruption type hardware exception and vector 1
>> (debug exception) or vector 18 (machine-check exception)."
>> 
>> Two tests, verify_nmi_window_exit() and verify_intr_window_exit(), try
>> to do something that real hardware disallows (i.e., fail the VM-entry)
>> by injecting #UD in HLT-state.  Inject #DB instead as the injection
>> should succeed in these tests.
>> 
>> Cc: Jim Mattson <jmattson@google.com>
>> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
>> Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
> Reviewed-by: Jim Mattson <jmattson@google.com>
> 
> Thanks for the fix!
> 
> It has always bothered me that there is no easy way to validate a
> kvm-unit-test on physical hardware. Do you have a mechanism for doing
> so? If so, would you be willing to share?

I call this mechanism “grub”. ;-)

If you saw my recent kvm-unit-tests patches - they are needed to run
kvm-unit-tests on physical hardware. Once I am done sending the remaining
fixes, I’ll send an RFC that enable test execution on physical hardware
(e.g., by skipping tests that require test devices).

I just hope that this support would convince you, and others, to prefer
(when possible) kvm-unit-tests over the selftest environment.

> I don't suppose you have a patch for kvm to fail the VM-entry in this case?

I am trying to keep my day job.