Re: [PATCH v4] KVM: selftests: Add a test for gPAT handling in L2

[Sean Christopherson <seanjc@google.com>]

On Fri, May 29, 2026, Jim Mattson wrote:
> On Fri, May 29, 2026 at 6:29 AM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Thu, May 28, 2026, Yosry Ahmed wrote:
> > > > +int main(int argc, char *argv[])
> > > > +{
> > > > +       TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
> > > > +       TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE));
> > > > +       TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) &
> > > > +                    KVM_X86_QUIRK_NESTED_SVM_SHARED_PAT);
> > > > +
> > > > +       if (!kvm_cpu_has(X86_FEATURE_NPT))
> > > > +               goto skip_npt;
> > > > +
> > > > +       gpat_test("Invalid gPAT", l1_guest_code_invalid_gpat, npt_enabled = true);
> > > > +       gpat_test("Nested NPT enabled", l1_guest_code, npt_enabled = true);
> > > > +skip_npt:
> > > > +       gpat_test("Nested NPT disabled", l1_guest_code, npt_enabled = false);
> > > > +       return 0;
> > > > +}
> > >
> > > The goto is really unnecessary here:
> > >
> > > if (kvm_cpu_has(X86_FEATURE_NPT)) {
> > >        gpat_test("Invalid gPAT", l1_guest_code_invalid_gpat,
> > > npt_enabled = true);
> > >        gpat_test("Nested NPT enabled", l1_guest_code, npt_enabled = true);
> > > }
> > > gpat_test("Nested NPT disabled", l1_guest_code, npt_enabled = false);
> >
> > Well, it's necessary to avoid the indentation.
> 
> Or refactor as:
> 
> if (kvm_cpu_has(X86_FEATURE_NPT))
>         run_npt_tests();

Anyone have a strong preference?  I like the goto approach (obviously), so that
that all the gpat_test() invocations are prettily aligned.  But I can live with
an if-statement as Yosry suggested.  I think the only option I don't like is
moving the NPT tests to a separate helper (it's two lines of code, and testing
the NPT case really is the focal point of the test).