From 0c55f867f0c96dff93d4e0b5973975d65afb26d8 Mon Sep 17 00:00:00 2001
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
Date: Wed, 2 Dec 2020 21:35:36 +0100
Subject: [PATCH] selftests: kvm/set_memory_region_test: Fix race in move
region test
The current memory region move test correctly handles the situation that
the second (realigning) memslot move operation would temporarily trigger
MMIO until it completes, however it does not handle the case in which the
first (misaligning) move operation does this, too.
This results in false test assertions in case it does so.
Fix this by handling temporary MMIO from the first memslot move operation
in the test guest code, too.
Fixes: 8a0639fe9201 ("KVM: sefltests: Add explicit synchronization to move mem region test")
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <0fdddb94bb0e31b7da129a809a308d91c10c0b5e.1606941224.git.maciej.szmigiero@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
.../selftests/kvm/set_memory_region_test.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index b3ece55a2da699..6f441dd9f33c94 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -156,14 +156,23 @@ static void guest_code_move_memory_region(void)
GUEST_SYNC(0);
/*
- * Spin until the memory region is moved to a misaligned address. This
- * may or may not trigger MMIO, as the window where the memslot is
- * invalid is quite small.
+ * Spin until the memory region starts getting moved to a
+ * misaligned address.
+ * Every region move may or may not trigger MMIO, as the
+ * window where the memslot is invalid is usually quite small.
*/
val = guest_spin_on_val(0);
GUEST_ASSERT_1(val == 1 || val == MMIO_VAL, val);
- /* Spin until the memory region is realigned. */
+ /* Spin until the misaligning memory region move completes. */
+ val = guest_spin_on_val(MMIO_VAL);
+ GUEST_ASSERT_1(val == 1 || val == 0, val);
+
+ /* Spin until the memory region starts to get re-aligned. */
+ val = guest_spin_on_val(0);
+ GUEST_ASSERT_1(val == 1 || val == MMIO_VAL, val);
+
+ /* Spin until the re-aligning memory region move completes. */
val = guest_spin_on_val(MMIO_VAL);
GUEST_ASSERT_1(val == 1, val);
--
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