Re: [PATCH v8 35/46] KVM: selftests: Convert with allocated folios in different layouts

[Fuad Tabba]

On Fri, 19 Jun 2026 at 01:32, Ackerley Tng via B4 Relay
<devnull+ackerleytng.google.com@xxxxxxxxxx> wrote:
>
> From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
>
> Add a guest_memfd selftest to verify that memory conversions work
> correctly with allocated folios in different layouts.
>
> By iterating through which pages are initially faulted, the test covers
> various layouts of contiguous allocated and unallocated regions, exercising
> conversion with different range layouts.
>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Co-developed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>

Cheers,
/fuad

> ---
>  .../kvm/x86/guest_memfd_conversions_test.c         | 30 ++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c
> index b43ac196330f1..0b024fb7227f0 100644
> --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c
> +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c
> @@ -279,6 +279,36 @@ GMEM_CONVERSION_TEST_INIT_PRIVATE(before_allocation_private)
>         test_convert_to_shared(t, 0, 0, 'A', 'B');
>  }
>
> +/*
> + * Test that when some of the folios in the conversion range are allocated,
> + * conversion requests are handled correctly in guest_memfd.  Vary the ranges
> + * allocated before conversion, using test_page, to cover various layouts of
> + * contiguous allocated and unallocated regions.
> + */
> +GMEM_CONVERSION_MULTIPAGE_TEST_INIT_SHARED(unallocated_folios, 8)
> +{
> +       const int second_page_to_fault = 4;
> +       int i;
> +
> +       /*
> +        * Fault 2 of the pages to test filemap range operations except when
> +        * test_page == second_page_to_fault.
> +        */
> +       host_do_rmw(t->mem, test_page, 0, 'A');
> +       if (test_page != second_page_to_fault)
> +               host_do_rmw(t->mem, second_page_to_fault, 0, 'A');
> +
> +       gmem_set_private(t->gmem_fd, 0, nr_pages * page_size);
> +       for (i = 0; i < nr_pages; ++i) {
> +               char expected = (i == test_page || i == second_page_to_fault) ? 'A' : 0;
> +
> +               test_private(t, i, expected, 'B');
> +       }
> +
> +       for (i = 0; i < nr_pages; ++i)
> +               test_convert_to_shared(t, i, 'B', 'C', 'D');
> +}
> +
>  int main(int argc, char *argv[])
>  {
>         TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM));
>
> --
> 2.55.0.rc0.738.g0c8ab3ebcc-goog
>
>