linux-kernel - [PATCH 15/20] KVM: sefltests: Verify value of dirty_log

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Message-ID: <20241214010721.2356923-16-seanjc@google.com>
Date: Fri, 13 Dec 2024 17:07:16 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Peter Xu <peterx@...hat.com>, Maxim Levitsky <mlevitsk@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 15/20] KVM: sefltests: Verify value of dirty_log_test last
 page isn't bogus

Add a sanity check that a completely garbage value wasn't written to
the last dirty page in the ring, e.g. that it doesn't contain the *next*
iteration's value.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/dirty_log_test.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index 3a4e411353d7..500257b712e3 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -514,8 +514,9 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long **bmap)
 				 * last page's 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_last_page ||
+				     page == dirty_ring_prev_iteration_last_page) &&
+				    val < iteration)
 					continue;
 			} else if (!val && iteration == 1 && bmap0_dirty) {
 				/*
-- 
2.47.1.613.gc27f4b7a9f-goog