Re: [PATCH 0/4] KVM: selftests: Fix and clean up emulator_error_test

[Sean Christopherson <seanjc@google.com>]

On Tue, Oct 04, 2022, David Matlack wrote:
> On Mon, Oct 3, 2022 at 4:31 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Thu, Sep 29, 2022, David Matlack wrote:
> > > Miscellaneous fixes and cleanups to emulator_error_test. The reason I
> > > started looking at this test is because it fails when TDP is disabled,
> > > which pollutes my test results when I am testing a new series for
> > > upstream.
> >
> > This series defeats the (not well documented) purpose of emulator_error_test.  The
> > test exists specifically to verify that KVM emulates in response to EPT violations
> > when "allow_smaller_maxphyaddr && guest.MAXPHYADDR < host.MAXPHADDR".
> 
> I thought that might have been the case before I sent this series, but
> I could not (and still can't) find any evidence to support it. The
> commit message and comment at the top of the test all indicate this is
> a test for KVM_CAP_EXIT_ON_EMULATION_FAILURE. What did I miss?

Being in the general vicinity when the test was written?  :-)

> Either way, I think we want both types of tests.  In v2 how about I split out:
> 
>  (1) exit_on_emulation_failure_test.c: Test that emulation failures
> exit to userspace when the cap is enabled, i.e. what
> emulator_error_test does by the end of this series.
>  (2) smaller_maxphyaddr_emulation_test.c: Test the interaction of
> allow_smaller_maxphyaddr and instruction emulation. i.e. what
> emulator_error_does at the start of this series plus your suggestions.
> 
> The main benefit of splitting out (1) is to test
> KVM_CAP_EXIT_ON_EMULATION_FAILURE independent of
> allow_smaller_maxphyaddr, since allow_smaller_maxphyaddr is not
> enabled by default.

Works for me.