Re: [PATCH 2/2] KVM: selftests: Test guest_memfd binding overlap without GPA overlap

[Sean Christopherson]

On Tue, May 19, 2026, Ackerley Tng wrote:
> Sean Christopherson <seanjc@xxxxxxxxxx> writes:
> > @@ -542,6 +542,26 @@ static void test_add_overlapping_private_memory_regions(void)
> >         TEST_ASSERT(r == -1 && errno == EEXIST, "%s",
> >                     "Overlapping guest_memfd() bindings should fail with EEXIST");
> >
> > +       /*
> > +        * Repeat the overlap tests, but so that there is overlap in the
> > +        * guest_memfd bindings (i.e. in guest_memfd file offsets), but _not_
> > +        * in the GPA space.  Regardless of where there's overlap, KVM should
> > +        * return -EEXIST.
> > +        */
> > +       r = __vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD,
> > +                                        MEM_REGION_GPA,
> > +                                        MEM_REGION_SIZE * 2,
> > +                                        0, memfd, MEM_REGION_SIZE);
> > +       TEST_ASSERT(r == -1 && errno == EEXIST, "%s",
> > +                   "Overlapping guest_memfd() bindings should fail with EEXIST");
> > +
> > +       /* And now the back half of the other slot's guest_memfd binding. */
> > +       r = __vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD,
> > +                                        MEM_REGION_GPA,
> > +                                        MEM_REGION_SIZE * 2,
> > +                                        0, memfd, MEM_REGION_SIZE * 3);
> > +       TEST_ASSERT(r == -1 && errno == EEXIST, "%s",
> > +                   "Overlapping guest_memfd() bindings should fail with EEXIST");
> 
> I just noticed this is kind of odd, what is the purpose of "%s" and then
> filling the string in with a hardcoded string?

Purely oversight.  I didn't even see it until you said something :-)