From: Sean Christopherson Date: Sat, 11 Jan 2025 00:30:01 +0000 (-0800) Subject: KVM: selftests: Tighten checks around prev iter's last dirty page in ring X-Git-Tag: v6.15-rc1~195^2~8^2~13 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2020d3b77a5a40a133e18fb4c870e9fe384405fd;p=thirdparty%2Fkernel%2Flinux.git KVM: selftests: Tighten checks around prev iter's last dirty page in ring Now that each iteration collects all dirty entries and ensures the guest *completes* at least one write, tighten the exemptions for the last dirty page of the previous iteration. Specifically, the only legal value (other than the current iteration) is N-1. Unlike the last page for the current iteration, the in-progress write from the previous iteration is guaranteed to have completed, otherwise the test would have hung. Reviewed-by: Maxim Levitsky Link: https://lore.kernel.org/r/20250111003004.1235645-18-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c index c6b843ec8e0c7..e9854b5a28f15 100644 --- a/tools/testing/selftests/kvm/dirty_log_test.c +++ b/tools/testing/selftests/kvm/dirty_log_test.c @@ -517,14 +517,22 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long **bmap) if (host_log_mode == LOG_MODE_DIRTY_RING) { /* - * The last page in the ring from this iteration - * or the previous can be written with the value - * from the previous iteration (relative to the - * last page's iteration), as the value to be - * written may be cached in a CPU register. + * The last page in the ring from previous + * iteration can be written with the value + * from the previous iteration, as the value to + * be written may be cached in a CPU register. */ - if ((page == dirty_ring_last_page || - page == dirty_ring_prev_iteration_last_page) && + if (page == dirty_ring_prev_iteration_last_page && + val == iteration - 1) + continue; + + /* + * Any value from a previous iteration is legal + * for the last entry, as the write may not yet + * have retired, i.e. the page may hold whatever + * it had before this iteration started. + */ + if (page == dirty_ring_last_page && val < iteration) continue; } else if (!val && iteration == 1 && bmap0_dirty) {