Re: [PATCH 13/20] KVM: selftests: Print (previous) last_page on dirty page value mismatch

Maxim Levitsky
2024-12-18T00:01:50Z

On Fri, 2024-12-13 at 17:07 -0800, Sean Christopherson wrote:
> Print out the last dirty pages from the current and previous iteration on
> verification failures. In many cases, bugs (especially test bugs) occur
> on the edges, i.e. on or near the last pages, and being able to correlate
> failures with the last pages can aid in debug.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> tools/testing/selftests/kvm/dirty_log_test.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index d7cf1840bd80..fe8cc7f77e22 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -566,8 +566,10 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
> }
> }
>
> - TEST_FAIL("Dirty page %lu value (%lu) != iteration (%lu)",
> - page, val, iteration);
> + TEST_FAIL("Dirty page %lu value (%lu) != iteration (%lu) "
> + "(last = %lu, prev_last = %lu)",
> + page, val, iteration, dirty_ring_last_page,
> + dirty_ring_prev_iteration_last_page);
> } else {
> nr_clean_pages++;
> /*
> @@ -590,9 +592,10 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
> * value "iteration-1".
> */
> TEST_ASSERT(val <= iteration,
> - "Clear page %"PRIu64" value %"PRIu64
> - " incorrect (iteration=%"PRIu64")",
> - page, val, iteration);
> + "Clear page %lu value (%lu) > iteration (%lu) "
> + "(last = %lu, prev_last = %lu)",
> + page, val, iteration, dirty_ring_last_page,
> + dirty_ring_prev_iteration_last_page);
> if (val == iteration) {
> /*
> * This page is _just_ modified; it

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>